A great debate continues over which is the "most compatible" recordable DVD format - DVD+R or DVD-R?
Most studies seem to show that under "normal conditions" the two formats are about equal and that something like 80-90% of modern DVD players can handle them, if the DVD's are encoded and burned properly. DVD-RW and DVD+RW generally have lower compatibility rates and really should only be used for internal purposes such as previewing DVD projects on players you know can handle RW DVD's.
But, DVD+R is able take advantage of the not-so-well known "bitsetting," also called "bit setting," "bit mode compatibility," "compatibility bitsetting" and probably some names I haven't heard of yet.
Whatever you call it, bitsetting is a process that changes the identity of a DVD+R disk as seen by DVD players. DVD-R disks have information embedded in them which identifies them to players as DVD-R. Replicated DVD's (ones that have been stamped rather than burned) are identified as DVD-ROM. DVD+R disks have no such embedded identity and, using certain DVD burners, it is possible to make the DVD+R disks identify themselves as DVD-ROM.
Certain older DVD players, including DVD players in some laptop computers, will not load DVD-R or DVD+R disks at all because those formats did not even exist when the player's firmware was written. However, by changing the bitsetting on a DVD+R to DVD-ROM, those players should be able to load and play the DVD+R.
HP DVD+R drives were among the first on the market with an option to change the bitsetting mode. Since then, other brands have been released with firmware that will allow the mode to be changed. Generally, bitsetting has not been available for any of the so-called "dual format" DVD burners that can handle DVD-R/RW and DVD+R/RW, however it looks like some advances are being made in that area and if interested click on this link: DVD R RW (www.cdfreaks.com/news2.php?ID=8780). While bitsetting can be pretty straightforward with single format DVD+R/RW drives, it appears to be a little trickier with the processes available for the dual format DVD burners.
If you go to the web site of DVDplusRW you will see that it has a good overview of the bitsetting process (www.dvdplusrw.org/Article.asp?mid=0&sid=2&aid=42) and they have another article about using software to change the bitsetting mode (www.dvdplusrw.org/Article.asp?mid=-1&sid=-1&aid=44).
If you use Mac OS X, try this a free compatibility bitsetting tool (www.plak.net/dvdplustool/).
If you would like to read some "real world" user reports on bitsetting, click to go to this bitset forum thread (www.netfarer.com/forums/index.php?showtopic=8) with some easy to comprehend explanations. On another forum, there's a post from one of the strongest proponents of using DVD+R and bitsetting for maximum compatibility: DVD+R bitset post (www.creativecow.net/forum/read_post.php?postid=107439529422588&forumid=155&archive=_2004|11|10).
Some DVD authoring programs, such as Apple's DVD Studio Pro, will not let you burn your projects to DVD+R. In that case you can build the video_ts and audio_ts folders and use Roxio's Toast to burn them to DVD+R.
Of course, no matter whether you use DVD+R without or without DVD-ROM bitsetting mode or whether you use DVD-R, the compatibility of your burned DVD's is dependent upon other factors. The brand of DVD+R or -R you use can make a big difference. Maxell brand has tested very well as have TDK, Verbatim and Mitsui (now MAM-A). Other brands have also received favorable user reports, but some brands consistently fail 50% or more of the time. Often these are "no name" brands that sell for far less than the better known brands.
How your audio and video are encoded also affects playback compatibility. The best rule of thumb seems to be to keep the total audio and video bitrate to 7Mbps or lower, use Closed GOP for the MPEG2 video and always compress the audio. Compressed audio can have a bitrate of about 128Kbps to 224Kbps, while uncompressed audio is more than 1,500Kbps! Some DVD authoring and encoding programs can only compress audio in an MPEG format that is not universally supported by NTSC DVD players. Dolby Digital/AC3 audio compression is supported by all DVD players. If you must use Uncompressed (PCM/LPCM/AIFF) audio, then your maximum video bitrate should be no more than 6Mbps and preferably less.
One more factor can also affect compatibility: how fast you burn the DVD's. I have seen many, many reports of compatibility problems being solved simply by going back and re-burning a project at 1X instead of 2X. However, in all fairness, I did hear from one user who said they burn at 4X and have only had two problem disks out of 100 burned at that 4X (they used MAM-A brand DVD's). They did not say how many different players those disks were played on, but I suspect that if it had been 100 different players they would have had a much higher failure rate than 2%.
If you really want 98% or 100% compatibility for your DVD projects, the only sure way is to have the disks replicated: you send a master to the replicator, they make a glass master and stamp the copies the same way the Hollywood movie's are copied to DVD. It's expensive for under 500 copies or so, but for certain projects it may be worth it for even 100 copies if you or your client is not willing to tolerate any bad disks being returned by customers.
If replication is not in your budget, then using good encoding and burning techniques and DVD+R with DVD-ROM bitsetting can help increase the odds in your favor.
Note: If you need
more info on the basics of DVD burning,
take a look at our DVD
burning instructional video.
Article copyright © 2004 by Bob Hudson
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© 2004 by Sign Video Ltd.
