RECORDING DATA on DVD BLANKS
I am trying to explain basic factors like format instead of what many sources do - assume
certain formats according to media type or limits of common software, and gloss over some things
that trip people up. I take that approach so that:
- you understand the primary factors, thus don't get confused by detail (as easily :-).
- people know of features that may be in their software but hidden in non-obvious menu
locations.
As well I provide information on specific traps, to help people avoid them (or at least understand what went wrong to avoid it next time :-).
Future revisions will be prioritized for my needs, which at this time are firstly data archiving/ backup and secondly limited music recording. (I also use this article as notes for my own benefit.)
This information is for general use, not for steering trucks or flying aircraft where deep understanding, thorough knowledge and rigorous testing is necessary. Use at your own risk, but let me know if you think it is in error.
Regrets, this page is in development awaiting more time to do, and more experience with or research on DVDs as different from CDs. URLs aren't even all coded as links!
In the meantime, and anytime for even more information especially on use for video, I recommend http://www.dvddemystified.com.
If you thought CDs were complicated, brace yourself for DVD physical details, then again for the variations in video content. Me, I'll stick to data for now. :-)
(DVD is maturing. Those who lived through the maturation of CDs can take a memory step back to be prepared for confusion, changes, and bugs in media description, drive firmware, and recording software. Why, even cartridges are back (used to hold compact DVDs in some video cameras).
The latest version of these notes is available at:
http://www.keithsketchley.com/dvdinfo.htm
or linked from within http://ourworld.compuserve.com/homepages/sketchley_keith_h/
NEW
(Mostly recent notes needing integration.)
- ISOBuster software claims to be able to create images: http://www.isobuster.com/help/image_file_creation_settings
- I've encountered Windows Explorer refusing to copy a file to a device other than the boot HDD because the filename is almost identical, and other cases where it handles files differently. I have not checked if the file system is different (e.g. FAT32 is often the default on external HDDs whereas NTFS is native to Windows XP).
- Memorex say that the center hole of DVDs is more fragile than the center hole of CDs, therefore they recommend using only cases designed for DVDs. As well, I've noticed that some music CDs and software CDs are packaged in the greater-retention cases that you must push in the center to release - just pulling the disc may break it. (If a disc is only cracked I'd try a bit of crazy glue - it you try to read it with cracks it may come apart at the high speed it turns in the drive.)
- apparently older DVD recording drives may not be able to record on faster blanks. Firmware update may provide the capability to use faster blanks, but at the original slower speed the drive was designed for. See http://www.memorex.com/service_support/faq.php for information; also Pioneer who made many of the drives that earlier had the problem - including many drives in Apple computers.
- 8cm DVD-RAM is pricey, shop around especially for clearouts (Circuit City prices seem better than most for small DVDs)
- dual layer blanks are still pricey, now down to US$1. each for name brand on sale. One must want the almost-halving of number of discs to pay that price, since regular DVD blanks are US$0.25 each - thus DL is about four times more costly for the same capacity. Only worthwhile for serious archiving or maximizing portability at this time.
- OTOH, the blanks that can be labelled in a capable drive are coming much closer to the price of regular blanks.
- I don't see much dual-sided, though I expect only really serious archivers or network-juke-box users will want them due hard to read labelling.
- I have been using RecordNow! version 7.x for a year, successfully, to make data DVDs for archive. It is much better than the earlier version I used with CDs, but lacks some features such as copying a music selection to hard drive to make a compilation off owned audio CDs for use in my vehicle. That feature is available in deluxe versions, if you can figure out their web site. Oddly, version 7 has features to copy an entire CD/DVD, such as saving the CD as an image, but not to copy a single selection - that's backwards.
UPDATE: I upgraded to RecodNow Premier, version 3 I think (numbering system is different than early RecordNow! products). It's a good news-bad news story.
> the user interface is much better, much larger for one thing.
> it has more capability
> but there are several bugs and awkward aspects, though it is quite useable, but I haven't bothered to reinstall it since I had to reload my computer.
Roxio's software development quality needs improving.
- many recording failures are caused by dirt on the disc. Be careful storing and handling. (I'm a fan of sleeves that have a soft porus lining, but they can trap grit.)
- If printing your own labels on the disc with an inkjet printer, don't overlook water resistance of the ink (lacking in many inks - Microboards technology recommends "water resistant media" from Taiyo Yuden for their duplicating machines, but I do not know how that media addresses the ink problem.
> I'm not paying attention to Blu-Ray and competing terrabyte-capacity discs until they become widespread thus cost-effective for my needs and portable (many other people using). However I noticed this link on Microboard's site. I presume competing formats have similar web sites - typically those promoting new things they want to see adopted widely have.
- I see something called "DivX (WMA) video files in the list of media handled by the DVD player in a Toshiba TV, apparently in several versions including 6.
My knowledge is primarily of Microsoft DOS/Windows operating systems. Readability sections contain some information on other systems, and some of the general disc and format information will be useful for those systems.
I do not cover details of video and I do not cover unauthorized copying.
Beware: DVD recording is at the stage of high sensitivity to quality of design details of drives and software, to quality of blanks, compatibility of drives with blank types, and even DVDs purchased with content already on - whereas CD recording has matured. At the higher cost of DVD blanks you may want to be cautious. You might check your drive maker's web site for ROM upgrades.
To be added list:
- compatibility of CDs with DVD drives should be good as CD-writing/DVD-reading drives.
- bridge version of UDF used on DVDs
NOTE: it may be that DVDs always use UDF
- The specification for the UDF file system used by DVD is available from http://www.osta.org/.
- check if anything but Mt. Rainier is relevant to fixed-packet format on DVDs, given vintage of the introduction of DVD recording software.
- review how recordable DVDs are made (somewhat different physically from CDs, but this article does not go into that level of detail).
*NOTE* Terminology is loosely used. I've noted confusion over "video" DVD. As well, I've seen Imation DVD+Rs with "RW" quite noticeable on the label but they are write-once not re-writeables (in that case the "RW" indicates that the disc is compatible with drives that can write on +RW discs - which came before +R). And I've seen packages without a speed rating, especially from Imation though they do state Version 2 thus you can reasonably assume the discs are 2X - see CAPACITY for why that is significant, and for the Authoring trap.
NEW
The DLA, MyCD/MyCDV, and RecordNow! products produced by Veritas and often bundled with HP drives, sometimes under HP brand, can now be found at http://www.sonic.com (Sonic Solutions). It seems that HP are now bundling a full version of RecordNow! which has more capability while still bragging about ease of use, and that MyCD is now a broader/larger product than RecordNow! (it includes RecordNow! and DLA as well as other software depending in part on distinctions involving the words "suite" and "deluxe" - check "what's new" for a table). From the web site it appears that DLA now supports the more reliable Mt. Rainier format, aka "Easy Write". (Note that the concept of "drive letter access" is not unique to Sonic's product, but theirs is called DLA.) And Sonic's site has a press release saying they've purchased Roxio's consumer line and that the Roxio company will morph into Napster. I don't know what this means for tradional Adaptec/Roxio products such as Easy CDC, Toast and DirectCD (which is not named in press releases - sometimes it is lumped with Easy CDC, and it is the subject of a patent lawsuit). No, I am not writing this on April 1. :-)
According to Sony's laptop computer website, there is a "DualDisc" with DVD content and CD Audio on one side and CD Audio content on the other. Sony advise that the DVD content on the DVD side will play on most Sony DVD players, but the audio side and the audio content on the DVD side may play on only a few because it does not conform to the normal CD audio standard. Furthermore, some CD drives may scratch the DVD side where the label would normally be on an audio CD.
For playing pre-recorded information (that has IPR content) note that viewability is typically restricted by region. http://www.amazon.com/exec/obidos/tg/browse/-/3193231/002-8166825-2672032 provides brief advice, listing 6 regions of the world that DVDs are typically not licensed across. If you want to view in another region you'll need to buy a version for it, if available. No, I don't want to hear about hacking!
I've seen a recommendation to use UDF format if recording a file greater than 2GB (as may be the case when making a recovery "image") rather than UDF/ISO. I don't know why, but somewhere there is information on recording problems with recording more than a certain amount on a DVD.
Blu-ray Disc
Say what?
Seriously, I don't have time to update this DVD information let alone chase new formats.
Higher capacity formats are initially of potential use where the current common format would necessitate too many discs for the particular use, considering user friendly aspects and size aspects. Examples of each are:
- the phone directory for the entire US takes several CDs, requiring the user to change CDs in the drive to look up numbers in a different area, whereas one DVD holds the entire directory
- a DVD takes far less space to store than a video cassette tape
(A push to higher capacity for DVDs is high-definition TV/movie material, which takes up much more space (though newer codecs help) and may require faster reading of the disc to support the motion inherent in those contents.)
Then cost and compatibility must be considered against the usefulness. For example, archiving data for one's own use does not require widespread compatibility provided that at least one other computer outside of your facility can retrieve the data.
Hardware and consumeables will be costly initially, decreasing to comparable with time and popularity as manufacturing process technology advances and economies of scale are obtained. For example, dual-layer DVDs are only now getting to that point.
Both of the primary competing formats for high capacity, Blu-ray and HD-DVD, use a laser at the blue end of the light spectrum instead of today's red end technology which is a 60% longer wavelength. The HD-DVD format is intended for greater compatibility with existing devices and manufacturing processes, whereas Blu-ray goes for even greater capacity and information-transfer speed. (The question of speed is muddied by better compression codecs such as MPEG-4, provided whatever is running the decompression codec can keep up.) Both use much tighter track pitch than standard DVDs, but for some reason (according to information on their forum) HD-DVD uses a slightly tighter pitch for the -RW version, the same pitch as Blu-ray, so approximately 2.3 times more track length than standard DVD. The combination of wavelength and track spacing multiplied by standard DVD capacity gives about the capacity claimed for HD-DVD, so Blu-ray must get more from another factor - probably more efficient encoding of the pit pattern on the disc). Additional features on both support more interactive content, improved audio function, and better protection of Intellectual Property Rights.
So, what about Blu-ray? The format holds up to 25GB on a single layer, or about 5 times as much as a DVD. It is an unofficial standard supported by 180 companies including movie distribution companies. Read-only and recordable media are planned, the latter in both write-once and reuseable form (BD-RE). A harder outside coating is planned (I don't know if HD-DVD does that, as I don't know if the coating is thicker thus impacting manufacturing). Claims for it include high speed. See http://www.blu-ray.com for more information. AKA "BD-DVD" for "Blu-ray Disc".
So, what abut HD-DVD? (Previously known as AOD.) The format holds about 15GB in the single layer form, or about three times that of a standard DVD. Claims made for it include that its construction is the same as a standard DVD, thus manufacturing cost should be close to the same. Device cost will presumeably increase as a second laser colour is required in the head. The file structure is UDF2.5. Higher rotational speed is used to get the speed, including a faster standard size DVD called "3X DVD". -R, -RW, dual layer, and mini (8 cm) forms are planned as well as more exotic variants comparable to the little used ones existing for today's DVD technology - but noteably dual configurations that may provide backward compatibility for movie producers if supported. See http://www.dvdforum.org for more information.
(Present and new DVD/HD formats include formats of lesser appeal, such as dual-use/content and double-sided (of greatest use for controlled archiving, perhaps for server juke-boxes, double-sided four-layer gives roughly four times the capacity of a standard DVD - which in Blu-ray or HD-DVD is a huge capacity by todays' standards, 60 to 100GB).)
Now that our heads are hurting from trying to grasp all the factors, I'll comment that which format prevails will probably depend most on the movie industry's choice (most major (North American - Japanese) producers seem to be favouring Blu-ray) and secondarily on price of devices to read them, as well as price of blank discs for data and and price of devices to write to them). If HD-DVD has minimal cost to modify device designs (though requiring another laser colour in the head), as well as its claimed same-cost of manufacturing blanks, it may survive as an "enhanced DVD" - especially if both formats can be accommodated in one device - while Blu-ray has a greater and longer future because of its 67% greater capacity if that is attractive as Blu-ray claims (they promote additional content on a movie DVD, not just accommodating higher resolution). Early indications are that at least some of the big name electronics manufacturers are producing players that can handle both BD-DVD and HD-DVD, albeit at a higher price - and player prices are high compared to standard DVD.
** NEW**
According to hubcanada.com of April 2008, HD DVD is being abandonned by supporters like Toshiba.
The article does point to factors to watch for with Blu-ray, especially the vintage of player "profile", claiming that "Profle 1.0" will not be firware upgradable, Profile 1.1 will "address the picture-in-picture issue", and Profile 2.0 will have many more goodies especially interactivity. For a price, no doubt.
The following factors apply:
1. TYPE of DISC
2. CONTENT & FORMAT
A. AUDIO
B. SEQUENTIAL WRITE
C. VARIABLE LENGTH PACKETS
D. FIXED LENGTH PACKETS
3. READABILITY
A. INDEXING
B. DVD-RW & +RW -RAM
C. RECOMMENDATIONS for WRITING for READING
D. DETAILS
4. CAPACITY
5. SOFTWARE
A. TYPES
B. QUALITY
C. AUTOMATION
6. SPEED
7. BACKUP/LONGEVITY
A. MEDIA
B. WEAROUT
C. BACKUPS ARE MORE IMPORTANT
8. MORAL ISSUE
9. CONCLUSIONS
10. THE FUTURE
11 - Appendices with more details on some factors:
APPENDIX A MORE CHALLENGES READING FIXED-PACKET/DVD-RW
APPENDIX B MORE TRAPS READING MULTI-SESSION DISCS
APPENDIX C MISCELLANEOUS TRAPS
APPENDIX D MORE CHALLENGES - WRITING
i - SPEED
ii - MISCELLANEOUS
APPENDIX E MORE GOTCHAS
APPENDIX F REFERENCES
APPENDIX G Draft of notes re backup
APPENDIX H Draft of Keith's Survival Guide
So read on in the order of the above list - or click the link to the section.
Originally DVDs were simply molded from a durable master, somewhat like stamping vinyl records but making pits that are covered by a reflective coating and a clear layer of plastic. Then came DVD blanks on which data or music could be recorded. Those writable DVDs have a dye or metal layer that is altered by the laser (and a reflective backing layer if dye type). They also have information about the blank pressed in the groove the reading head follows. The read/record head(s) location is controlled by a servo motor system that optically senses the groove and follows it.
Recordable DVDs come in write-once and re-writeable types, equivalent to CDs but with different formats in each type.
Write-once should be used when you want wide readability, you don't need to add or revise files many times, and you don't need to recover space. (Of course, CDs have wider readability because many more computers can read them.)
Re-writeable should be used where you want full flexibility of deleting and adding files, are willing to accept substantial limitations on readability, and are willing to pay the higher price of the discs. (Though they are useful for temporary use such as backup, when used with write-once format.)
However, you also need to understand what format the user might best be able to read. There are more types of basic DVD formatting, and the field is still settling out. I am aware of the following media types, and compatibility with reading drives:
- DVD-R (widely compatible, similar to CD-R)
- DVD+R (perhaps more widely compatible than -R)
- DVD-RW (rewriteable, medium compatibility, similar to CD-RW)
- DVD+RW (rewriteable, medium compatibility, supports "lossless linking" which helps when recording is stopped and started as in a video camera)
- DVD-RAM (not very compatible as it has major differences)
(The blank type must be compatible with the DVD-recording drive to make the recording. Early drives did not handle all types of blanks.)
It is important to understand the difference between physical format and application format. The foregoing are physical formats, whereas terms like DVD-Video and DVD-AR are loosely used where content is included.
Note there are special application formats for game devices such as Sony PlayStation 2 and Microsoft Xbox.
Also note that Laserdiscs are not compatible with DVD-Video discs. (Let's recognize laser discs as a pioneering format providing capacity for high resolution and greater durability. But at a size close to that of an LP record.
Note that VCD and SuperVCD are formats placing video on standard CDs, and a "mini DVD" puts DVD-quality video and audio on a CD. Confusing? It may have confused me - I need to check the mini-DVD term, recognizing that terminology is loose.
And there are other video complications, such as 16:9 versus 4:3 display aspect ratio, the various file formats such as MPEG and QuickTime, and the NTSC versus PAL TV display incompatibility.
Completed discs may contain one of the following:
A - audio in a format matching original music DVDs (DVD-DA format).
B - sequentially written continuous data, usually on write-once discs
(This is the original DVD format, providing data files or audio tracks. The writing can
be done "track at once" or "disc at once".) A variant of this format is "multi-
session" in which data is added at a later time.
C - data broken into "variable-length-packets", usually on write-once discs. Reasonable readability.
D - data broken into "fixed-length packets", necessary for using re-writeable discs as if a
large floppy disc on which you you write or delete file by file when you choose.
(Pre-formatting required; limited readability due to UDF format and low reflectivity of
RW disc material.)
Refer to Readability for finalyzing actions such as "closing" that affect reading in standard DVD drives.
I'll reiterate the limitations and complexity of the issue of readability encountered with DVD-RW discs themselves, and the UDF fixed-packet format usually used with them. Their flexibility of writing comes at a price of restricted readability. (The emerging Mt. Rainier format is robust and portable but not yet maturely implemented in drives and software - see References for info.)
Discs for use in audio disc players should be single session CD-R discs, audio format, closed before distributing.
Audio discs can be written one music track at a time, or the whole disc at once. There
may be a slight advantage on older players to writing a track at a time. (I speak of audio
discs playable in a normal music player - data discs can of course contain music in
computer-type files such as MP3 and WAV. Never mind that your computer may appear
to show files with .CDA extensions on the audio DVD - those are actually tracks.)
[Change this section to cover the "video" version of DVD.)
Writes in a continous stream of bits, as a single "image". "Mastering" pre-assembles the data to write the entire disk in one pass, then it is closed to ISO9660 level 1 Table of Contents (the most widely readable). You must assemble the complete contents in organized form on your hard drive, or stream the bits from a fast playing DVD reader through a fast computer.
Multiple sessions take more space and add complications of reading the table of contents if certain things aren't done. Each session can be "closed" after writing it, but once the disc is "closed" you cannot write any more to it. (Though on a Re-Writeable disc some software may be able to reverse the closing action - the option pops up in Nero Express 5.5.9's Erase feature if the re-writeable disc is in closed ISO format.)
For a multi-session disc you should choose Mode 2 (aka XA) format if you have a choice in the software, as some drives need that. (A Kodak PhotoCD is in XA format. Some drives were optimized too closely to that pioneering format so cannot read a multi-session disc made using Mode 1.)
Files are broken into variable-length packets, which may be inter-leaved. Useful for adding files incrementally over time then, when finished, converting to ISO configuration for readability in non-writing drives. (That conversion or closing is to ISO9660 level 3.)
May be referred to as "formatted" but is simple, unlike the formatting of fixed-length packets. Packet-writing software will usually default to variable length on DVD-R media, as the reuse facilitated by fixed packet is not available on DVD-R media. This format is often used by backup software, which may have its own restore method instead of providing simple readability of the disc. Requires at least 15 MB to finalyze,
The format using fixed-length packets facilitates easy deletion and addition of files as done with floppy and hard disc drives, on a disc that can be erased (a re-writeable disc, usually called a DVD-RW disc. Packet writing software will usually default to fixed-length on DVD-RW media.
But fixed length takes disc space for formatting, whereas straight variable-packet takes far less as noted above.
Note that while use of the disc is like writing to a floppy, you cannot format the disc in Windows Explorer - separate software is needed, usually supplied by the drive manufacturer. (Apparently the copy-file capability in Windows XP is a version of Roxio Easy CD Creator, using Roxio's version of ISO format, not packet software - nor DVD capable AFAIK, though it might get added by a Service Pack.)
Fixed-packet format requires the disc to be "formatted", which identifies areas where the data is to be placed during writing and re-writing (deleting data and re-using the space on ReWriteable media).
A disc may be returned to blank state by "erasing" it.
Some software offers a choice of "quick erase" or "full erase". Quick erase deletes all data - but as with floppy diskettes and hard drives that only hides the data so the space can be re-used. Full erase wipes out the data (except for forensic recovery technqiues).
I am advised of a trap with DVD+RW media which cannot be erased, only reformatted - some software does not gray out the erase option, and trying to erase the disc may result in a condition that writing software has difficulty with. Did I tell you that the DVD subject is more complex than the CD subject?
You need playing software plus decoding software (often called a "codec"). Microsoft Windows 98, Me and 2000 come with DirectShow, which can play DVDs if a third-party decoder is installed and the computer CPU or video card is fast. For Windows XP go to Microsoft's web site to get a decoder to use with Windows Media Player. Quicktime versions 6 and later may handle DVDs fully.
An indexing method on the disc is essential. It is what the computer's file recognition system uses to know where each file or track begins, to make a directory list or find a specific file. In most cases a finalyzing action called "closing" is needed to finish the TOC for widest readability. (Your software may use different terms for that, or do it automatically.)
There are four types of indexing methods affecting broad use.
- Audio discs, straightforward except in mixed audio-data format.
- ISO 9660 level 1 Table of Contents, the original CD format
- ISO 9660 level 3, necessary with variable packet writing (after closing) and/or multi-session.
- The "map" arrangement that is used with fixed packet writing on a CD-RW disc.
(There may be an ISO 9660 level 2 that allows 31 character file names.
The ISO 9660 level 1 format is widely used, readable under several operating systems
including DOS, Windows, Unix and Mac (with caveats for other than Windows).
However, recording software may not use that format until you "close" the disc. (The
popular Easy CD Creator, for example, uses its own format before the disc is closed,
but its support of ISO 9660 is generally better than most software.)
An ISO 9660 Level 3 Table of Contents cannot be read by Windows 3.1/3.11, and Mac o/s prior to System 8, because the o/s or its extension such as MSCDEX cannot deal with files on a CD being in pieces instead of a continuous chunk of data. (Non-Microsoft patches may be available.)
With fixed packet-writing software like Direct CD the disc cannot have a final Table of Contents like normal CDs. The computer's software translates the disc's detail map into what your computer's normal software, such as Windows Explorer, can deal with using a normal CD drive. That capability is built into the latest operating systems, or you can obtain a file called a "UDF Reader" to install on the computer to read the disc. Refer to an Appendix for details.
And don't panic when you can't display directories (lists of disc contents) correctly. See notes elsewhere in this document and Appendices for traps and tricks, and recognize you can try a different drive or computer (with options of transferring data using another format or media type that may be more readable, a network, or a transfer cable with Windows' Direct Cable Connection function if both computers have Windows9x (or DOS6's INTERLNK/ INTERSVR client-server commands if one or both computers do not).
(I'll briefly mention the native MacIntosh file system, HFS. DVDs written to that format cannot be read by other operating systems, but discs can be made in hybrid format by special software. And like PCs, Mac o/s vary in their capability to handle newer things like DVDs.)
Note especially the readability limitations of fixed-packet software, including incompatibility of the format produced by various brands of software and vintages of UDF.
ReWriteable discs present an additional reading challenge not related to format. The drive must accomodate the lower reflectivity of the material. I expect that all DVD drives can handle it, given that CD-RW media had been accommodated by the time that DVD reading drives became common.
The term "erase" may be used too loosely. On ReWriteable media using fixed-packet packet format you can delete files, the information will still be on the disc until the space is re-used by adding files - as is the case with a floppy diskette or hard drive. ReWriteable media can be returned to truly blank unformatted state by software that "erases" it.
(While write-once media of course cannot be changed,on a multi-session unclosed disc you can change files by adding the new versions or hide files by adding directories of the same name as existing ones but not containing the files. In those cases the recording process provides a new index and hides the old one. But beware I have had trouble with it showing only the new files.)
For widest readability use sequential writing (ISO 9660 level 1), single session, with 8.3 file names containing only capital letters, numbers, or the underscore symbol ("short" file-names in Microsoft lingo), and no more than eight levels of subdirectories. The Joliette extension of ISO 9660 includes long file names and broader language support (note that Macs can only handle file name length of 31, DOS/Windows only 8.3 name format.)
Note that making the master for commercial DVD replication for wide use may require a specific format and process. See CAPACITY for some variations such as Authoring format.
Readability of multi-session discs is normally good, but until the disc is closed you may not be able to read the full contents. (I'd expect software to automatically close each individual session. See Appendix B for more yabuts. In general it is best to avoid multi-session recording if you want the widest usability of discs.)
The flexible format often used with ReWriteable discs, fixed-packet format as used by DirectCD et al, has only recently been standardized in the "Mt. Rainier" format. Until then discs created with most brands were not compatible with other brands, though some UDF readers could read some other brands' discs.
You may need to do special things for widest readability on different operating systems. DVDs can be written in a "hybrid" format so they seem normal on each operating system - that is commonly done for PC-Mac use - but special writing software may be needed. (Check http://wwww.macdisk.com and http:/www.roxio.com, as well as http://www.apple.com/switch.)
DVD writing drives can read discs in cases where standard drives cannot, even with multi-read and UDF capabilities. With the accompanying software installed in the computer they can handle more situations and accomodate some errors, such as not having a closed table of contents.
Quality of writing drives and discs can affect readability.
Note that files on DVDs will be in read-only format, so when you copy them back into a computer you may have to change the file attribute to writeable (some application software wants write access to the file before you even ask it to change the file). [to be checked]
Capacities of regular size (12 cm) DVDs include:
- DVD-5 (4.7GB)
- DVD-9 (8.54 GB, dual-layer single-side)
- DVD-10 (9.4GB, dual side single layer)
- DVD-18 (9.09GB, dual-side dual-layer)
- DVD-RAM
- early versions are covered later in this section.
- "HD-" capacity using "blue laser" or Blu-Ray standard is something that in the future will provide greater capacity.
However for most people anything but the 4.7GB basic DVD is academic due cost and practical matters such as how you label a dual-sided disc.
Compact DVDs (8cm) are available in some types, typically 1.4GB in DVD-R, +R and rewriteable versions, which some people call "mini" DVDs, some "camcorder" DVDs, and also in a DVD-RAM version used by some video cameras.
And it gets more confusing:
Usable capacity of the disc depends on type, layering, overhead factors described earlier, writing software, and disc manufacturer. DVDs were introduced at 3.95GB (DVD v1) but now 4.7GB (DVD v2) is standard, except for the incompatible "Authoring" version of DVD-R which may be more common in the smaller capacity (it has slightly wider spacing of the groove spirals).
(Beware of the capacity confusion over use of either 1000 or 1024 bytes per KB thus a 2.4% variation, as with hard drives and file manager software. 4.7GB on a DVD is 4,700,000,000. bytes. (1024 is a common number in computing, as it is a power of 2. EG 2x2x2x2....=1024, and it is commonly used instead of 1000 - hence a GB could be 1,000,000,000 or 1,024. cubed (1,073,741,824) depending on whose dialectic you speak. :-) But I doubt I'll miss the 7.4% enough to lose sleep. :-)
Standard discs will hold over two hours of high-quality digital video (MPEG-2 compression standard). (Movie DVDs may include data such as multiple languages, extra camera angles, and extra-interest information.)
Refer to Types above for additional capacity numbers. (Yes, dual layer capacity is not twice single layer, as the more-transparent first layer cannot hold as much.)
Also, "compact" DVDs are available, the 8cm size whereas normal CDs and DVDs are 12 cm diameter. BR>
(Beware that camcorders may require a carrier (piece of plastic in which a normal compact DVD sits), that there are square and round types of carriers, and different media (such as DVD-R, DVD-RW, DVD-RAM (which offers twice the capacity of normal DVDs).
I've looked at Maxell's square carrier and conclude that care is needed to remove and insert the disc to avoid scratching.
I do not know what the difference between the Video version and normal DVD types is. In some cases the term is used to mean factory-made discs with video content (rather than audio or data content) but for recordables it means something else. Some makers label small CDs as Camcorder, perhaps when a carrier is included.
Maxell's web site has much DVD information, including articles at http://www.maxellcanada.com/dvd_tech/dvd_pdfs.htm, but lacks precision.
The advantage of compact DVDs is of course their small size - they fit into small pockets and wallets whereas regular DVDs can be somewhat awkward. Unfortunately sleeves are uncommon (they'll fit in boxes and pockets meant for 3.5" floppy disks but won't be retained well in open pockets - you'll need to go mail order - plastic cases, clear plastic sleeves, and paper sleeves are avaiable from http://www.sleevecity.com and http://www.winmedia.com, as well as display mailing envelopes, but not the nice sleeves with grit trapping material inside. ).
Software is usually of these types:
- sequential write software like Adaptec/Roxio's Easy CD/DVD Creator, Ahead Software's
Nero, NTI's CD-Maker, and HP/Veritas' RecordNow.
They write data disks closest to ISO9660 format for wide readability, and write
conventional audio discs. They should handle multiple sessions.
- packet writing software like Adaptec/Roxio's Direct, Ahead Software's InCD, HP/Veritas' DLA and NTI's FileCD which use UDF formats for fixed and variable length packets.
- backup software like HP/Veritas Simple Backup, Adaptec/Roxio's TakeTwo, and NTI's Backup NOW!. (See the Backup/Longevity section and the Appendix on backup for factors to consider.)
- A disc erasing utility is useful for salvaging a corrupted ReWriteable disc by returning it to blank status.
Usually the fixed-packet software installs on your computer in a way that makes it always available in the background to read and write individual files using a ReWriteable disc as though it were a huge floppy disc. That might interfere with use of sequential-write software.
From my experience I make these comments on brands of software:
- HP may supply software with their name, actually made by Veritas.
I find it is not as functional as competing software, unless you pay for upgrade to a higher priced version from Veritas, and its user interface is poor (with minimal Help information). MyCD and its improved version RecordNow! does have some good features, such as doing write speed and read speed tests at the beginning of a job. I recommend against HP/Veritas DLA as it is not mature and not compatible with DirectCD's widely used format.
(HP may mix sources for different software functions in the same drive package. That is inviting trouble, but may give you DirectCD rather than HP DLA - that's good.) Thus I would hesitate to purchase an HP drive. (If you need an external drive I suggest a BackPack whose current CD product comes with USB, parallel and PCMICA interfaces and last I checked provided Adaptec/Roxio's full-featured Easy CD product family.
- Adaptec/Roxio had a reputation for bugs in new releases, but they release n/c version updates that fix bugs, have a good web site, and provide capable software.
- RecordNow is now owned by Sonic. Recent versions are much more capable than the circa-2000 version bundled with HP CD-recorders. They seem sensitive to file naming causing a "moved/could not be found" error message during recording. In one case that was caused by a file name extension of .mh rather than normal .mht, in another case by arabic characters in the file name - obviously not very robust software (though Microsoft is inconsistent within its own software - file names can be created by SaveAs from Internet Explorer that cannot be read by Windows Explorer).
- Nero gets praise from many people. (It is for audio and standard data writing. Its companion fixed-packet software InCD is not well known.)
- I am advised that Sony's B'sRecordGold has an "o/s compatibility" selection which checks factors like filenames and number of directories for compatibility with different
operating systems and advises the user. That sounds useful for advanced users (new users
should just stick to simple sets of files and ISO 8.3 filenames).
- I am advised that Sony often bundles yet another incompatible type of fixed-packet writing software with their drives. Some users change to more common software such as DirectCD.
(Purchased versions of the main software for audio and standard data writing usually have fixed-packet software and bonuses on the CD, even though it is labelled with the name of the main software and may install a user interface that appears to be only that name.
Drive manufacturers will usually provide both regular and packet writing software, not necessarily from the same software vendor. Make sure you are getting good software, or a good drive at a price that let's you buy good software separately.)
While software for low-volume DVD recording is usually made for Windows and later MacIntosh o/s, there is software for DOS - though it typically supports only SCSI interface not the ATAPI/IDE interface more common in PCs. Try www.goldenhawk.com, who also make software for Windows. I understand that software is available for Linux but I know nothing else about that. Linux pioneers are probably happy to tell you (and IMO Linux is still in "pioneer" stage).
WINDOWS
Windows XP has limited functionality for recording to CD. Primarily it writes an "image" of selected files to the CD, probably in Roxio's C.... "almost-ISO disc arrangement.
The image file is assembled in a staging area on the hard drive where it is called "StashImapi.bin", then written to the CD on command. Assembly is by drop-n-drag or SendTo the drive letter or by manual copying to the staging area. Some settings are available in a Properties box.
Windows XP does not provide the packet-writing capability needed to treat a DVD-RW disc like a giant floppy and re-use space. Refer to Knowledge Base articles Q294883 and Q279157.
Windows XP can erase a CD-RW. (The menus containing the command are context-sensitive, depending in part on what Windows thinks the state of the disk is, thus confusing.)
For DVDs we await addition of that capability to Windows XP, perhaps with a Service Pack, perhaps in the next generation of Windows, hopefully with a properly designed User Interface. Meanwhile third-party software like Nero is available, but check Microsoft's Knowledge Base to see if there is risk of conflict with the built-in feature.
Software is essential to use of your drive, unlike now standard floppy and hard drives which are fully supported by the operating system. For DVD writer drives, great hardware with poor software does not work - at best you'd have to buy better software separately. So choose it well to ensure it has the features you need and has few defects.
The better software also takes care of a number of details to improve your success rate, and lengthen the life of your ReWriteable discs.
Of course it should have minimum number of crawling insects (defects, popularly known as bugs), but beware the industry and technology is not mature.
Some software automates too much, not telling you what it did or did not do. Fine, until you have to diagnose. (But this article helps you, right? :-)
The software may automatically do something, such as choose the type of packet writing by the type of disc. Much of the information I provide herein is to help when you have trouble, provide information so you know there may be settings in the software, and to educate you on limitations of drives, discs, formats, and software. This is leading edge technology by home and office standards.
Software may use different terminology (for example, "lock" or "finalyze" instead of "close" on a DVD-R, "image" vs "ISO"), or describe a usability result such as "this DVD will only be readable in a writing drive". You remember to look in Help to find out what the software can do, don't you? :-) (OK, some software doesn't have complete Help info.)
You may have to scrounge around to find the settings. For example, some options, including closing of an R disc, are under Explorer| Properties (select drive and right-click in the right window pane or in a Properties tab in the writing software), some are found by right clicking the CD icon in the task bar of Windows (DirectCD under Windows 98SE).
Note that the speed rating system is different for DVDs than for CDs. A 1X DVD would be roughly a 3X CD. It appears that DVD recorder specifications use the DVD rating system even for CD capability.
In one-pass sequential writing, the computer and file source must be able to keep up with the recording speed. You don't get a second try on a DVD-R disc (it isn't even usable as a coaster, because it has a hole in it :-). Speed is especially a problem if the material is not well assembled on your hard drive or is being read concurrently from another DVD-ROM. (Recent better drives do have feautures to reduce the risk.)
I recommend you start at a low writing speed to be conservative, increasing if your experience is solid, but stay low if you want to be extra safe for longevity. See Appendix C for more yabuts and advice.
Note that external drives will be limited by the port speed (standard USB is quite slow, about 1X, probably similar for parallel if the computer is fast).
DMA access should be set for all drives rather than PIO.
For most people longevity of the disc is not an issue, provided they are kept out
of sunlight and high temperatures. Good knowledge of the longevity of DVDs requires time yet to pass, as the technology is only a few years old. (Manufacturers have made changes to prevent problems such as sensitivity to sunlight and deterioration of glue. Theoretically. Kodak claim their Ultima discs include gold for longer than silver, thus may well be worth the higher price if your data is irreplaceable. Also note that color of the disc is not the prescription many people think it is, as it does not cover all factors
and may be altered by other materials in the disc. Among the features claimed by long-life discs are non-flaking label surface and scratch resistant opposite surface. (In addition to Kodak's Ultima Gold (no longer sold for CD at least), Verbatim offer "Datalife Plus" discs in both CD and DVD capacities, and Maxell offer their "pro" discs which have scratch-resistant layers under the label surface. (Verbatim's standard product may be called "Value-Life" or just "Datalife".) As well, Fuji are offering "CD-R Photo for optimum storage life" (www.fujifilm.ca), Fuji are selling a "photo" line that seems to offer greater durability and sometimes use the term "archive life", and Imation a "Business Select" line for greater durability. Some sellers use a term "archival", with wild claims like "300 year storage". Brands may include Adtec, HHB, Maxell, and Verbatim.
Otherwise best results will obtained using high quality DVD-R disks intended for long life, good recording drives, quality software, slow speed, and storage conditions that are dark, dry (40% RH is suggested) and near room temperature (definitely not hot). If you need to be very sure, you might copy DVDs at five years of age onto new DVDs, or make more than one backup set using a different brand and recorder for each.
Scratching may limit life. I believe that DVD-RW discs may be more easily scratched, and can wear out as covered in the following section. Sony is advertising that their DVDs for video cameras are 100x more scratch resistant than standard ones.
Also note that the reflective layer is just behind the label thus easily damaged. So don't scratch the label, don't try to erase info on it, and use felt markers made for the job (permanent non-alcohol, or Sharpies fine point permanent markers).
With laser discs a phenomenon called "laser rot" was of concern. The metal reflective layer would deteriorate. I wouldn't worry about it on DVDs which are made of better materials and have lower bending stresses due to their much smaller size.
DVD-RW discs are good for about 1000 re-writings. For most people using good drives and software that is not a concern. However, I suggest limiting re-use of backup discs to 100 uses just to be sure the data is there when you need it. Some people just treat them like floppy discs - they wear out too.
Note that some software avoids re-using areas recently deleted from (Windows tends to re-use such areas first). As well, the combination of DirectCD and Windows Explorer over-writes all files of the same name, rather than only those with later date-time, thus causes more wear than necessary.)
Manufacturers are developing longer-life DVD-RW discs, but the question will be the price difference considering the user's needs. (One can just throw away the worn disc, but users depending on recovery of the information may want to throw them out early or pay the price for longer-life discs, because a disc may appear to take the information but be difficult to read from later.)
For backup of your important data, there are other considerations including:
- whether your method images the drive completely enough to just put the image on a new drive and use the computer quickly,or whether just backing up data is enough for you (in which case if the drive was replaced you reinstall all software then load the data).
- special backup software is a whole subject of its own. (It may not behave the same as your normal writing software, it may use proprietary formats requiring the original software, it may use executable files on the disc to restore the data, etc. Its main advantage is automation of the list of directories and files you normally back up.)
See Appendix G for more considerations.
And I'll reiterate the importance of quality discs, quality recording, and proper storage.
My advice if using DVDs for full backup is to test a backup to make sure you can read it in the primary internal DVD-ROM drive - not the writing drive, especially if it is external (which may use drivers not in the standard installation of your operating system). For full backup you may need a bootable DVD drive. (You can set your computer to first boot from an internal DVD drive instead of the hard drive.) Make sure you check out every step in the process that you would have to use in the disaster scenario.
And you keep the backups in a different building than the computer - right? :-) (Preferably in a trusted place out of your earthquake/flood/tornado zone.)
I support Intellectual Property Rights. You should not copy other people's property, like pre-recorded music disks. (I think that copying a few tracks to compile a disc of favorites is fine, provided you own and continue to own the original DVDs.)
Recordable DVDs are still leading edge by home and office standards, thus not as simple and foolproof as established methods of storage.
In general DVD-RWs are most useful for:
- Added flexible storage attached to the computer (used like an additional hard drive or
huge floppy diskette).
- Frequent backups for the purpose of recovering accidental deletions of a few files.
Otherwise DVD-R discs are superior due to their lower price, wider readability, and write protection.
For widest readability take the conservative approach of using:
- DVD-R discs of 74 minutes length (650MB)
- regular ISO9660 level 1 form (short file names of simple characters, standard
recording not packet method)
- closing disc after writing, to that form
- not too many small files
- slow recording in one session
- quality drives, software & discs.
And keep the discs in a dry, dark, temperate place - secure but not forgotten.
Be prepared to work through finding options in your software, and traps of displaying directories of disc contents.
10. THE FUTURE
Oh, friend, pal, buddy - you can tell the future? Which stock should I buy? :-) More seriously, this is new technology and it is evolving. Capabilities such as life and recording speed are improving. There will be a few wrinkles though - such as the inability of older recording drives to write to the newer hi-speed CD-RW discs. And you'll encounter myths and other misinformation. (If you think my article contains some, please let me know. ;-)
APPENDIX A - MORE CHALLENGES READING FIXED-PACKET/DVD-RW
Formatting to fixed length packets puts a "runout track" on the disc, so it does not need closing later (and can't be closed). As data is written a map is kept of where the pieces of files are. The UDF reader function translates that into a directory that suits your normal software.
To obtain UDF Reader software to install on a computer without a very recent o/s,
- visit the website of your software maker, or
- check for an option in your writing software or its install DVD to create the file, or
- check your drive's install DVD for filename udfrinst.exe
One tip for DVD-RW discs is to turn off read-ahead caching. Some drives don't fully comply with industry specifications for multi-read, so may have difficulty with areas between packets where the laser recorder ramped up and down.
Refer to http://www.ahead.de/en/download.htm for InCD's UDF reader, and compatibility of versions of it and versions of InCD with different UDF readers, and to http://www.roxio.com/en/support/udfmac/index.html for similar variations in the version of UDF used by Adaptec/Roxio products and Mac o/s. (Version 3.39 seems to read DirectCD 3xx discs. Information from Ahead is that InCD 1.3 used a UDF format not compatible with InCD 1.61 and later.) Be aware that Veritas' DLA software that HP has been providing is not compatible with DirectCD's format, and that the function built into Windows XP are not compatible with DirectCD.
Note that a fixed-packet RW disc is not write-protected, until DirectCD messes up and makes it read-only. :-) (Actually, that may be a software hangup not a disk attribute - try restarting Windows.)
Note that errors were common on the old removable rewriteable media, floppy disks. DVD-RW discs contain far more files, which might increase risk of error – though the media is different and non-packet formats include some information facilitating automatic error correction. The "Mount Rainier" standard is intended to make fixed-packet DVD format more robust. Apparently it is implemented in both software and the drive, otherwise I have not studied it (I hope to find time to try to read a DirectCD 3xx disc with a bad file).
Note each version of UDF, and each brand of fixed-packet software, is not fully compatible with others. As well, changes are expected including a more robust format and inclusion of the capability in drive hardware to eliminate need for special software. (I am leery of how compatible that will be with existing installations.)
If a ReWriteable or fixed-packet disc has file read errors try it in a different drive, especially a recording drive. Also, sometimes copying one file or one directory at a time works when copying several gives errors. Then record the problem files to a freshly erased and formatted ReWriteable, or better yet to a WriteOnce in ISO form.
APPENDIX B - MORE TRAPS READING MULTI-SESSION DISCS
Newer/better software includes the file list for all sessions in the last session on the
disc. Use may be automatic, or by your command such as Import Previous Session, so the list is readable. Otherwise drives may see only the last session, as they are not multi-session capable. (I have seen this from HP/Veritas MyCD which does not have an option to close, and allows multiple added sessions.)
A fine point of multi-session DVD-R discs is that you can update files by adding the new version - the software should change contents pointers to ignore the old version. It is still there taking up space, since space cannot be re-used on a DVD-R, but should be transparent to your using software. However, with HP/Veritas MyCD I have seen problems with directories - existing material in directories of the same name as added material is not longer visible.
I've seen Windows 98 Explorer show only the amount of the last session under Properties, though the directory listing and file listing were complete, of a disc in CDFS format created by HP/Veritas MyCD/RecordNow being read in both a read-only and a recording drive.
APPENDIX C - MISCELLANEOUS TRAPS - READING
If your DVD is only for Macintosh computers you can use HFS instead of strict ISO.
Some versions of Mac O/S and Unix may have difficulty with the file version number that full ISO compliance adds to the filename (in format ;n).
UDF format may default to Joliette long file names.
Also, putting a large number of small files on a disc may make it unreadable by older operating systems. (Including all MS DOS/ Windows ones that can only read FAT16 directory format, not the newer FAT32 used by Windows 98 and a few versions of Windows 95). Regrets I do not have guidance on the maximum number of files - you could look up the basics of FAT16 vs 32 for clues (may be 244 files).
As well, it is possible to add enough small files to a variable-packet disk that it cannot be closed due to limitations of FAT16, thus will only be readable in a writing drive. (Closing/finalyzing writes a TOC to the disc, and adds a runout track needed by reading drives. The end result is essentially the same as multi-session but the intermediate process may be more convenient than sequential writing.)
Apparently older players, especially in automobiles, may not be able to read DVD-R discs as their reflectivity is a bit lower than molded DVDs.
I have encountered situations where I had to disable the DirectCD feature of staying in the background for easy use of the DVD-RW disc as storage, in order to use other CD writing software. (It may be that ejecting the CD-RW disc will eliminate some problems.)
I've also had cases where running DirectCD itself temporarily disabled reading of the drive (until I re-started the computer). As well, I've seen the drive be unavailable because the disk notification box has not been acknowledged because it is hidden behind something else. (If you don't close the Ejected box and close it after the Inserted box appears one of them will hide behind what you have in view.)
And I've experienced mis-reporting of how much could be written to a CD-R disc, until I cold-booted the HP external drive (the software was using the capacity for fixed-packet formatted discs not the non-packet format being commanded - which has less overhead).
File names can cause recording problems. For example, a file with name extension .mh instead of .mht caused failure during recording. Also watch out for super-long file names, sometimes coming from saving a web page - not only might they exceed allowable length such as 106 characters, Windows lets them occur with no name extension but recording software probably does not.
I tried a version of ScanDisc (that supplied as a utility with an HP drive) on an RW disc. It flagged a file I knew was causing problems (offering to delete it), and identified many bad sectors that it could map to an error-free location. However, I did not have time to fix all of them so could not evaluate the end result (apparently the software's "automatically fix" option is not fully automatic or it does not respond to selecting the option, so I had to respond to an error message for each sector). However when I subsequently erased and formatted the disc much less space was available, so apparently it did block the bad sectors or more. (The disc had been used extensively for backup, by Direct CD. I threw it away. (However, I was able to erase one problem disc by using a different computer (different drive and software).) ScanDisc may be worth trying if you have a problem DVD-RW and do not have a duplicate or the source data to create a replacement - hopefully you'd get some data off the disc. Otherwise I'd make a duplicate and erase the problem disc.
Apparently hooking up internal DVD-ROM drives has traps. Master versus slave, problems sharing and IDE/ATAPI port, and enabling of PIO mode 4 instead of DMA are among issues I've heard of. To have a hard drive and DVD on the same IDE port requires setting PIO mode separately for master and slave positions - older systems cannot do that. (Quality is good in BIOS, not just in DVDs and DVD drives. :-) However, some DVD recording software does not cope well with a DVD reader and DVD recorder on the same port. (While DVD-ROM drives use the same type of port as hard drives, handling in the BIOS and software is not identical. (Hard drives use IDE, DVD drives use ATAPI add-on to IDE and implementation varies. I've seen a BIOS claim an added DVD drive was not ATAPI compliant, but it was.)
People new to DVD recording may confuse the term DVD-R/W, used for the drive, with DVD-RW the media type. I avoid the term DVD-R/W, preferring DVD Recording Drive (but drives fitting that term were once only capable of recording on DVD-R media as DVD-RW did not exist).
APPENDIX D - MORE CHALLENGES - WRITING
i - SPEED
You may need to shut down programs running in the background. Get advice on how to do that with your operating system. (Many utility programs are started when your computer boots up into Windows, but aren't in the normal Windows programs Startup menu and don't show up on the bar at the bottom of your screen.)
In general, I suggest a clean boot before recording. That should clear memory and lingering file-in-use flags (which Acrobat and Outlook are especially prone to).
Also, run Defrag on your hard drive to ensure files are actually in one place so they can be read more quickly (normally with deletions and additions some scattering occurs - pieces of files can occupy different areas of the drive).
Writing of large files may encounter automatic re-calibration by the hard drive or the DVD writer, which interrupts data transfer - which could ruin your DVD-R disc. Better drives wait for you to finish.
Writing many small files will be slower, because each must be opened.
Pre-mastering of the disc image will reduce speed problems. That assembles everything into one huge image file on your hard drive, which is then just copied to the writing drive in one session. (Pre-mastering writes the TOC at the beginning, as it knows every thing you asked it to put on the disc and assumes that you don't intend to add more later.)
And if you take bulk CDs out of the original package or throw the wrapper away, you may not know their speed - some discs are labelled with speed, many not. Writing a 2x disc at the 4x that recent software may default to is probably not a good idea. :-)
The conservative approach is to write slowly. Start the automated process then go to lunch. :-)
I recommend that before beginning to record a WriteOnce disc you cold boot your computer, including the external recording drive if that is what you have. I've seen problems with recording to an HP external drive if any disc insertion caused DirectCD to pop up its dialogue box. (Use the non-packet software's "Make Another" command to make more than one identical disc, commanding drawer closer through that software, as inserting a fresh blank WriteOnce by closing the drawer with the recorder's button may cause DirectCD to get in the way.)
ii - MISCELLANEOUS
Discs for a stand-alone recording drive must be audio type - that information is pressed into the grooves in the blank.
Note that the inherent nature of a DVD-RW disc, including its physical shape, means it cannot be write-protected - unlike floppy discs which have a hole that must be filled in order to write on them. A DVD-R disc is write-protected, in effect, by closing the disc.
Apparently it is possible to write packets to a disc that was started with a sequential write session but not closed - so be careful you have the correct disc in the drive.
There is confusion over allowable combinations of format and disc type. I think any
format can be used on any disc type, in theory. However, only some combinations are
really useful, so some software limits you to those. A simple approach is:
- You are paying the price of using DVD-RW, in disc cost and unreliability, to get its flexible re-write capability thus fixed-packet use may be of great value.
- But I do use DVD-RW for backups, sometimes.
- With DVD-R discs you only get limited second chances (and only by adding session(s), so fixed-packet is of no value. (Hmm - worse, you'd have a formatted disc with no files on it. Really useful!)
For those into a lower level of details, there are bytes and blocks of binary data on an audio DVD, but no files as such - no header. Your o/s directory function lists the tracks like files - on my computer just Track01.cda, Track02.cda....
A copy is not a copy? Software that appears to copy a DVD may not actually make a
literal copy, 100.0%. Subtle details may be changed or omitted. To figure that out,
you probably need to get into understanding "images" and what your software actually
does (typically it does not write true ISO9660 but its own unique adaptation, sometimes offering a closer configuration in an obscure place in its menus).
Also note the difference between copying files and copying a DVD. Files can be copied onto the hard drive then written to a DVD. Using packet software files can be copied to a DVD-RW individually, from any source. When copying a typical DVD-RW it is best to copy files not the disk because the source DVD-RW may be fragmented.
There may be limits on the number of files on a DVD (perhaps depending on use or length of long filenames), limits on length of filenames (110 characters), and limits on number of sub-directory levels. They may vary with the operating system and software used. (Apparently Nero can write "relaxed ISO" with more than 8 directorylevels and path information longer than 255 characters, but I do not know what software can read that.) If you want to write strict ISO I suggest you change file names yourself, as writing software will truncate to names that may be less meaningful (I've seen Nero truncate, including using xxxxn.zzz where n was 1, 2 and 3 where the first part of the original filenames was the same).
Locked files: note that files written to DVD often have the attribute ReadOnly when they are copied back onto the hard drive, even when from a DVD-RW disc, perhaps depending on the operating system. To change the attribute, them, open WinExplorer and:
- highlight the folder(s) or file(s)
- right click for menu then command Properties
- uncheck Read-Only (if grayed out using ALT-R works)
- repeat for all folders and files at lower levels (action on a folder name does not
change the files in it)
Note that the cursor must be in the highlighted area for the Properties command to
correctly display and take action on the attributes.
If you are into spending time trying to use older drives, I suggest you will find greater usability if the drive complies with the MMC command set. (I do not have leads to the MMC definition.)
When using packet software such as DirectCD you may find that the disc can be read but not written to. Check that DirectCD is running (it may have been disabled during troubleshooting or because the computer reverted to an earlier registry due problems).
DVDs play from the inside out toward the periphery, though some header-like information may be at the end (outside).
Some software has a volume setting for recording audio discs, buried down in menus.
Labelling can be a bother. It must be on straight to minimize imbalance in fast drives. One label company produces removable labels that may be handy for DVD-RW discs. Ink jet printers with DVD-printing featurs are now available.
And what about defects in writing software and recording drives? For example, LG's web site offers a firmware flash upupgrade with this cryptic explanation: "Improvement Point: enhanced recording of some DVD-R media.". Now I'm worried. :-)
APPENDIX E - MORE GOTCHAS
I've seen several anomalies in reporting contents of a disc, especially a DVD-RW:
- Windows may not accurately report space available on a DVD.
- Some recording software incorrectly shows the space available on a blank 8cm DVD as the 700MB that a full size DVD would have (Nero Express 5.5.9.9 for example).
- Space remaining may show as zero in some places, especially with WriteOnce discs or read-only drives. (In Windows 98, Control Panel|Properties will show the actual amount used, which you can compare with the disc capacity, considering the different overheads as described earlier. In DirectDVD using its Properties button/tab may also show unused space. (That function may also allow adding or changing the disc label.)
- Windows, with some DVD writing software, may not refresh the directory or disc volume label in Explorer when you change DVDs. Try F5 or shutting down and restarting Explorer or Windows as necessary. (Explorer may display the label of a previous DVD when the current DVD has no label.)
- I've seen a CD-RW reported as having a single file whose name had no apparent relationship to the contents, when attempting to read it with Win31's file Manager in a drive that probably could not read an RW disc's low reflectivity.
- I've seen files not shown as on the disc, by Windows Explorer original edition, yet the Copy command asks if the user wants to over-write the file. (Using DirectCD3.xx. F5 did not show the file.)
- And there are other traps with PCs that may look as though there is a problem with a specific disc. For example, PKZIP version 2.50 for Windows will advise "file not found" then "incorrect password" if you try to open an individual file from within a password-protected zipped archive on a DVD, but work if you copy the archive to the hard drive - even without chaning the read-only status.
- It seems as though the TSR to use the DVD-RW as a huge floppy interferes with some other functions of the drive.
- A recording drive must have autorun on (notify on insert) to use the TSR for packet writing. That is not convenient for database DVDs that also contain an install program, and you'll be putting wear on a more costly drive. (Though prices have come down so much wear may only be a concern with the new DVD recording drives whose price is higher though decreasing.)
To copy an audio disc, the player must support Digital Audio Extraction – otherwise you'll get some noise on the copy. (Some recent CDs use techniques to prevent DAE, for copy protection - apparently they sound bad in honest listening if the computer's player has a fully digital listening path.)
Keep in mind that DVD recording drives are slow compared to hard drives. Treat them like a floppy drive - give them a bit of time to finish doing whatever they need to after deleting or writing, and to be recognized after changing the disc. (For example, DirectCD has two periods of drive activity after inserting a CD. Trying to read the CD before the second period starts tends to foul DirectCD up. Also, closing/finalyzing a variable-packet CD may take a few minutes on a slow drive.)
If you damage the covering on the printed face of the DVD, it may not work as the light may just pass through. (Caution if buying DVDs in bulk at low price: some have no printed side, because they are meant for volume production equipment that applies the covering to label the DVD. (Some might consider that an excuse to buy the low priced inkjet printers now available with a DVD-holder and flat feed to print on DVDs. :-)
A ReWriteable disc may not be erasable due to corruption of the TOC. Exposure to strong light, especially UV, may work.
You may have times when the DVD drive does not eject the DVD using the button. I suggest trying these in order: closing the software that was using the drive, looking for an eject command in software, and turning power off then using a large paper clip in the hole intended for releasing the tray (first read the instructions for your model). DirectCD usually installs with an icon in the Windows tray (bottom of screen) - right-clicking on it should show a menu that includes Eject.
Before using a cracked disc, you might find an old slow speed drive. Recent drives turn at very high speed - there is some risk the disc could come apart thus not be readable, and damage the drive.
APPENDIX F - REFERENCES
TABLE OF CONTENTS
- GENERAL
- FORMAT
- SPECIAL
- MEDIA
- DVD/VCD/VIDEO
GENERAL
Hewlett-Packard's web site has good guides in its Product Support database. (Search on general keywords in addition to your drive model number.) Other drive manufacturers may have information on their web sites.
Compuserve forums have information and advice. Outsiders may be able to see some of the forum information, at www.compuserve.com.
http://www.mrichter.com/cdr/primer/primer.htm is a "Primer" on the subject, with depth. (Opens to a Table of Contents - much detail available by selecting subject. He provides the technical reasons behind many of the statements in this article.)
The Puget Sound Computer User newspaper recommended CD Recordable Solutions by Martin C. Brown as worthwhile. They advised it attempts to be comprehensive but is somewhat variable in its depth on each subject. They also mentionned Peachpit's book Little Audio CD Book as a peppier but non inclusive book.
FORMAT
http://www.osta.org for highly technical information on UDF, Multi-Read, and Multi-Play requirements.
http://www.roxio.com has FAQs and tips on readability for users - dig around, follow the links from one FAQ to others to find it all.
http://www.macdisk.com has information on CD images especially for Mac operating systems. It provides a very readable explanation of how a hybrid PC-Mac CD is possible - they produce software to create a hybrid CD on a PC. As well, it explains ISO image formats used by various writing software and explains how to create a true ISO image.
See also http://www.macdisk.com for FormISO which can build an ISO9660 image under DOS.
See http://www.roxio.com/en/support/udfmac/index.html for UDF readers for the Mac, including a note that Mac o/s 8.1 handles only an earlier version of UDF whereas DirectCD uses a later version.
Ricoh may have advice on their web site - I've read a good article called "Multi-Session CD Recording: the Rest of the Story" from Ricoh.
Drives (such as LG's sold in mid-2003) and software (such as DirectCD 5.3.1 and recent InCD versions) are now embracing the Mt. Rainier format, which is robust and more portable. However, note you may have to set the software to write in Mt. Rainier format rather than its normal packet format. [move into software section]
SPECIAL
The Support section of www.dantz.com has some special utilities for people deep into things. (Dantz sell backup software.) The Solutions section has tips and advice for backing up your computer or network.
This site has info on professional recording of music:
http://www.digidesign.com/products/promusic/ptbasics/
This company sells software for recovering problem CDs and examining CDs:
http://www.dtidata.com/products_ff_cdrom.asp
Here is an unchecked link to software for examining content of CDs, possibly to help recover files:
http://elpros.si/CDCheck/
http://www.roxio.com/en/interest/burning/cdburner_performance.html has information on recording speed.
http://www.verbatim.com has good info.
Software called IsoBuster may be able to recover files not visible in the TOC written by the last session of a multi-session disc.
MEDIA
Disc makers like Imation and Maxell may have basic information on their web sites, if you can put up with the slow loading of Maxell's site.
(Here is a modest-volume CD copying station.)
(Maxell are rearranging their information pages, but try this one:
http://www.maxell-data.com/focus/index.htm)
Kodak provide simple information to get you started:
http://www.kodak.com/US/en/digital/cdr/how/
and more detailed answers in their publication library (search it for CD-ROM):
http://www.kodak.com/global/en/service/library/index.shtml
The web site of I.D.Rom vendor Rompus Interactive provides some information on the business card sized CDs.
Those CDs come in at least two versions, none of them actual business card size:
- one is approximately 6 cm high between straight edges, the other two edges follow the 8 cm round shape. Memorex is one brand.
- the other is approximately 6 cm high, rectangular, and appears to be about 8.5cm wide, perhaps a bit more. Imation and CompUSA make some.
(The 6 cm dimension may be as much as 6.3 cm on some brands, and labels may be made to the larger dimension thus awkward to use on the smaller cards.)
Rated capacity of the two card shapes is the same. (CDs use a single track beginning at the center, so capacity of these forms is limited by the height.)
Supposedly they fit tray drives, though I don't know how the rectangular one fits well enough to center properly (drives used in laptop computers hold the CD by its center hole thus should hold these well). According to one producer of children's software the round ones do not work in the slot drives that Apple used on some Macs - I presume the card style will not.
In my opinion they are cute, but as they are not actually the size of business cards and the 8cm round discs are quite small but with over three times the capacity the "business card" size is only useful for its appearance - it gets noticed.
Round 8cm discs:
(Several years ago music was issued on them, akin to a "single vs LP" record difference.) Prices have come down, selection is greater, and both WriteOnce and ReWriteable blanks are available. I understand they are widely readable, though limited reports suggest the ReWriteable version is even more troublesome than the full size ReWriteable discs. My drives hold them well (one in a depression in the tray of a standard drive, the other by the center hole method of laptop drives). Check tax rate in Canada, in case they are considered equivalent to mini-discs. Apparently they are used in some digital cameras and MP3 music players, so prices have come down due to greater volume.
They may be called "mini DVDs" - not to be confused with "MiniDisc" which is a Sony magneto-optical media of about the same size, "compact DVDs", or "Pocket DVDs".
They are 2/3 the diameter of regular discs, but much easier to tuck away (slightly smaller than 3.5 inch diskettes).
Capacity is only 1/4 of a regular DVD, because surface area varies as the square of diameter so gross area is less than half, and the unused dimension at edge and center is the same so net usable area is small.
I've seen plastic cases sold separately, but not envelopes. (You could try cutting them from the corners of 8x10 or larger envelopes, or folding the end of coin envelopes over (the 86x152 mm ones). And if anyone has individual diskette envelopes in a dusty corner, they should work. Some people may find the flat diskette boxes at Staples useful for holding 6 of the 8cm CD cases - or perhaps other diskette boxes, as the CD case is approximately the same size as a 3.5" diskette. The CDs are much thinner than 3.5" diskettes so some holders are not usable.
Hopefully the use for MP3 players and cameras will help ensure they are supported for years. (Has anyone seen 2 inch floppy diskettes recently? (I saw Fuji LT-1 diskettes in Cal's surplus store. :-) (Hey, that's better than the 2.88MB version of the 3.5" diskette - I've only seen one, which came with the drive I foolishly bought.)
There is a small round format by Sony called mini-disc, but it is a sophisticated magnetic technology using a laser to heat the media to magnetizable temperature.
LABELLING
- labels must be centered accurately to avoid vibration as the drive spins at high speed
- use only felt marker pens for writing on the disc's label side (non-alcohol, permanent ink)
- if using ink stamps you'll need the special expensive ink that gives stronger coverage
- inkjet printers are now available with holders for DVDs, at home budget prices. (You can purchase DVDs with a plain white surface to print on.)
DVD/VCD/VIDEO
(Not complete nor up to date.)
DVDs are most popular with video users, secondly for data sets that would require several CDs. (For example, large phone number listings, encyclopedias, and map sets are readily available on DVD to provide the convenience of not having to switch CDs. Laptop users might especially appreciate those as one disc can be kept in the drive for reference (Microsoft Encarta Deluxe, for example - a five CD set including encyclopedia and dictionary).
A guide to recording DVDs and related formats, including assembly/recording software, was published in a recent issue of Performance PC magazine, www.performancepccanada.com.
From that I list media types:
- DVD-R (widely compatible)
- DVD+R (perhaps more widely compatible than -R)
- DVD-RW (rewriteable, medium compatibility)
- DVD+RW (rewriteable, medium compatibility
- DVD-RAM (not very compatible)
DVD capacities include:
- DVD-5 (4.7GB)
- DVD-9 (dual-layer single-side)
- DVD-10 (9.4GB, dual side single layer)
- DVD-18 (dual-side dual-layer)
However for most people anything but the 4.7GB basic DVD is academic due cost.
(VCD and SuperVCD are formats placing video on standard CDs, "miniDVD" puts DVD-quality video and audio on a CD.)
And there are other complications, such as 16:9 versus 4:3 display aspect ratio, the various file formats such as MPEG and QuickTime, and the NTSC versus PAL TV display incompatibility.
Some leads to video assembly/editing software:
- Ulead (now Roxio?)DVD Workshop
- Adobe Premier or Encore
- Sonic Foundry (including Vegas and the more advanced DVD Architect)
- Pinnacle Studio
- www.magix.com
- Roxio's ECDC4.0 may have limited capability to create a video CD from movie files, recent versions of Roxio and Nero software have much capability.
- DVD-Lab is powerful at an attractive price, with simple interface, from Mediachance.
- Apple's DVD Studio 2.0, for the Mac of course
Various levels of automation may or may not be provided, to reduce the number of steps you need to take to do the job.
A brief overview of DVD format options and recorders is at: http://seattletimes.nwsource.com/html/personaltechnology/134465540_ptdvd01.html (Seattle Times of June 11, 2002). As well, Verbatim may have simple guides. Some recorders can handle more than one format. And PC Magazine of January 2003 had a comprehensive article - may be available at http://www.pcmag.com/solutions. Smart Computing magazine of January 2003 has an article on recording to CDs and DVDs. DVD+RW information is available at: http://www.dvdplusrw.org. They indicate it is more interoperable with CD formats than other common writeable DVD formats such as DVD-R and DVD-RAM. Video CD may be covered at http://www.vcd.org
DVDs should contain a UDF file structure and may contain an ISO file structure.
Older DVD players may not play VCD format. (Older or cheaper DVD players handle fewer of the DVD formats.)
It appears that the X in speed rating of DVD recording drives is 4 times that of what is used for CDs, but I have not had time to verify that. (It isn't quite as simple as a simple ration - for some considerations the ratio is much higher, but 4X seems a good single figure to use for general understanding.)
The MacFixIt web site contains reports of difficulties playing DVDs, especially movies, including the bizarre experience that a regular DVD (commercially produced) would only play in a troublesome drive after it had been played in another drive, preferably a home DVD player. Problems vary with drive brand (Matshita, Apple and Pioneer get bad mention) and o/s - Mac 10.3 may be better than 10.2.
http://www.dvdhs.com provides information on recording drives that have trouble with higher speed blanks, including links to drive manufacturer's sites. Notable in the list are Pioneer, Apple (whose standard embedded drives may often be Pioneer) and Sony - though other makers may not have fessed up. Don't get confused by Apple's use of the term "SuperDrive" - they mean a DVD recording drive not an LS120 drive.
COLORS
(Of CD specification books not media.)Red: digital audio and CD Extra
Yellow: Data CD (mode 1)
Green: CD-ROM XA & CD-I (mode 2, form 1 and form 2)
Orange: TBA (Not another acronym, but To Be Advised :-)
[need info on DVD specifications]
Appendix G - Draft of notes re backup
Features to consider:
1. Replace files of earlier date, leave others (faster than over-writing all as WinExplorer/DirectCD does on DVD-RW). Usually called "incremental", you have to keep the previous backups going back in time through the last full backup.
2. Flag files no longer in current folders (i.e. may have been deleted).
3. What media? (e.g. floppy vs CD vs DVD vs tape, single vs "span-disc set")
4. Restore method and readability. (E.G. simple copying vs automated restore routine. Some backup software uses its own executable included on the backup media. Some backup software creates an image from which one may or may not be able to restore individual files - you want top be able to restore individual files because restoring the entire drive would over-write any changes in registry/setup since the backup.) Some software creates a disc that is not readable in a read-only drive, so you have to have a recording drive (and the drivers for it, really user-friendly!).
5. Backup of files only or entire hard disk.
6. What support is needed to restore? (E.G. are special CD drivers needed to restore that may not be on a new or reformatted hard drive? Often the software that makes Recovery or Disk Image CDs provides a floppy that boots into DOS, with complications, or requires the computer be set up to have CD drivers available in DOS or Safe Mode (such as a boot floppy (which Windows 98SE can make with generic drivers) or addition of real mode device drivers in the AUTOEXEC.EXE and CONFIG.SYS files (which are still there underneath Windows 9x). (Those drivers may not be provided by the installation of the recording software which is Windows-focussed.) Windows XP has its own scheme of startup menu options, custom boot floppy, or generic boot floppy set (see www.microsoft.com and search on "floppy boot" [sic]). And note the BIOS setup may need to be changed to boot first from the CD/DVD drive rather than the hard drive.
7. How does the software assemble the backup? (It may require it to be stored on the hard drive before transfer to removable media - thus requiring much spare space on the drive.)
PC Magazine of January 2003 has a recommended features checklist for backup.
The user manual for Retrospect Express may have guidance beyond just instructions for using RE itself.
And don't overlook the need for physical separation. (Once I was a director of a non-profit professional association. One day I was in the city of its office, distant from mine, and dropped by to check how the major purchase of a year ago was working - its first own computer system. I asked where the backups were. The last backup, made several months earlier, was on the shelf under the computer! I not only told the manager that backups should be made regularly, but he should take them home. (I'll grant that I do not know if they backed up paper files. The organization had a large membership list and other data important to its functionning.)
IMAGES
- the term "image" in the context of discs means a faithful copy of the entire contents and structure, usually as what looks like a single file to typical o/s directory functions
- in contrast, copying the contents of a disc file-by-file may not reproduce the structure (an extreme example being copying files from a floppy disk to a DVD).
- it may contain individual files within it but in a form not readable by the normal directory functions of a computer. A rough parallel is a zipped file - one must either unzip it into its constituent files or have extra software that can look inside the zipped file. (When a CD-ROM drive is installed under DOS thus Windows "family 1" the Microsoft program MSCDEX is installed to provide that ability for a conventional DVD. (For a fixed-packet DVD a "UDF reader" program of the right version and brand is needed.)
- The software that assembled the image file will provide some type of list within the file - often called a Table of Contents, for example. The list and referencing within the file may be called a "file system". It may or may not allow the file to be spread across multiple CDs (later versions of PKZip do, MSCDEX does not).
- the term is used in mastering a DVD by assembling the contents on the computer's hard drive then writing it to a DVD in the common ISO9660 format. The result on the CD is sometimes called an "ISO image", and on the hard drive it is usually in a modified-ISO format proprietary to the DVD recording software that you use to assemble it.
- by now you may observe that use of the term "image" is somewhat variable. For most people the precise definition may be less important than knowing the file is not the normal kind that regular computers can handle - "what extra capability do I need to deal with it?", and what it does for you compared to normal files.
- http://www.macimage.com provides much information on "disk images".
- note that a disc need not use the normal structure we expect in standard DOS and Windows, and may not have the same capacity. The key is that it can be read for its particular purpose - which may be by an installation routine on the disk itself.
- also note that an image of the complete contents of a hard drive is not necessarily everything on the hard drive, as the hard drive may use some space for its own calibration data (as well, there may be a small area that is only accessed by some o/s functions or by simple routines that will have to be installed again).
Alternative Media
Over the years several media formats were produced for backup, some providing far greater capacity than the popular media of the day (be it 3.5" diskettes or CDs). However, as technology advances most have disappeared, replaced by DVDs or in a few cases by newer special media formats.
Tape media seems to persist. For reasons I do not have knowlege of, some people like it. (I have not checked how well DVD-recording can be automated, but I comment that portable hard drives or high speed networks can also be used to take a backup copy of data off site.)
Appendix H - Draft of Keith's Survival Guide
1. This is leading edge stuff - many of you will have problems, many of you will get confused. But it is not "bleeding edge", so press on and learn.
2. While DVDs all look the same to the novice, they are not. See point 5 regarding construction and writing format.
3. While software makes the DVDs look like floppy and hard disks, they are not - in part because they are not fully integrated with older operating systems. You will see things that confuse you, including things that are plainly misleading, and encounter differences in how the types of media are handled. You are accustomed to using hard drives & floppy disks - and the software for them works well though not perfectly. DVDs are not at that stage of understanding, user interface, and maturity of software function.
4. Treat written DVDs like floppy disks were in the days when sizes and even formats differed, thus readability depended on:
- drive capability and vintage of operating system (e.g. PC DOS3 used different format than DOS2)
- condition/ quality of the diskette (errors were common on those rewriteable disks).
(If your mind, your memory, or your use of computers is not that old, I expect you get the general picture anyway. :-)
5. Learn the essential differences between manufactured DVD, DVD-R, and DVD-RW discs, and between normal writing software and that needed to use DVD-RW discs as giant floppies. (I suggest starting by using the simple guidelines in my article, then progressing to more detail and more variations as you get the basics locked into your memory for good recall.
6. Use simple ISO disc at once recording on DVD-R discs for widest compatibility and best reliability.
Use DVD-RW and fixed-packet software only for temporary non-critical flexible storage on the same computer or computers you know are fully compatible in hardware and software. (If you really want to use fixed-packet software, try to get a drive and software supporting the Mt. Rainier format and provide users with compatible UDF Reader software.)
7. If you are doing a particular task often, make a checklist specific to what you are doing, to help ensure you do all necessary steps and avoid traps.
8. When a problem occurs, don't panic - re-read my article to see if there is a workaround or recovery method or simple trap you fell into.
9. Patience.
10. Be extra careful with DVDs that contain material no longer on your hard drive. That is even more important than for regular data backups - they are your data, the source of their content no longer exists. See point 7 to help ensure a good result.
And the short list of basic factors and advice:
- A recording DVD drive requires recording software, except with the newest o/s which include some software.
- DVD-RW media can be reused many times, DVD-R media is write-once (but can be done in separate sessions).
- Audio (music) DVDs for general use are a unique format. (And some software and recorders require blanks encoded as special for audio recording.)
- Using a DVD-RW disc as though it is a giant floppy disk. It requires fixed-packet writing software and is as unreliable as floppy disks. There are several different formats, each requiring its own Reader, except for the new more robust and portable Mt. Rainier format.
The discs must first be formatted, and can be wiped with "erasing" software then reformatted.
(Usually that software is separate from the software used to record normal data and audio DVDs. Fixed-packet software hides in the background, so the file software such as Windows Explorer appears to work normally.)
- Data DVDs are normally written in one of the ISO9660 levels. They need to be "closed"/ "finalyzed" after recording for widest readability.
- Mac and Unix o/s are different from PC o/s, with limitations on interchange especially if you don't keep it simple or use hybrid disc formats.
- Record slowly, especially if your drive is external or your PC slow or you are using cheap discs. (Reboot before recording, and if it is really slow learn how to maximize computer speed without changing the hardware.)
- A recording drive may be able to read DVDs that a read-only drive cannot. Different drives may read better or worse if you did not follow the next point or if a drive or disc is failing.)
- Quality is a good thing, in drives, media and software. DVD-recording life is too complex already without adding flakiness to the puzzle.
- Conservative is good for widest use or greatest dependability. Keep it simple, do it slow, and be thorough.
- IPR is moral, don't steal it.
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