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What is bitsetting (bit setting compatibility bitsetting, bit mode compatibility) with regard to DVD Drives/writers and is it an important feature?

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CD/DVD/Blu-ray drive/writer problem: What is bitsetting (bit setting, compatibility bitsetting, bit mode compatibility) with regard to a DVD drive/writer?

I was on the point of buying a well-reviewed DVD writer - the LG GSA-41208 - but then I read somewhere about how a bitsetting feature can improve disc compatibility. This particular drive doesn't support it. Can you please explain what bitsetting is? I want to buy a drive that can play and record to the widest range of disc formats.

Answer

There are other terms for bitsetting - bit setting, compatibility bitsetting, and bit mode compatibility.

At the moment, only certain brands of DVD+R and DVD+RW disc writers can apply bitsetting. With DVD-R discs bitsetting isn't possible because the field that is changed by bitsetting is pre-set during the manufacturing process.

There is an entry called the Book Type Field that is in the start-up section of each DVD disc. This contains bits of information that tell the drive what kind of disc has been loaded - whether it's a DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW or DVD-RAM disc.

In order that a DVD drive or home player can identify what kind of disc is loaded, it queries the Book Type Field. The few bits of information in that particular area of a DVD disc, commonly referred to as the compatibility bitsettings, are programmed to tell the drive which of the low-level format specifications the disc media is, such as DVD-ROM, DVD+R or DVD+RW, etc.

Most DVD players can read a DVD+RW or DVD+R disc, but a small minority of them can't recognise the format at all and can therefore report a disc error when a disc is loaded that is not marked as an ordinary DVD-ROM disc in the compatibility bits. Usually, these players are physically able to read the disc, since the reflectivity of a DVD+RW disc is identical to that of a dual-layered DVD-Video disc that all players must be capable of reading, but compatibility problems can arise due to different interpretations of these bits in the various firmware versions. Therefore, in most cases, the problem can be solved by updating the firmware. But in cases where a firmware fix is not available, or when you want to increase the chances of playability when you give the disc to other people with an unknown player, you could solve the issue by using bitsetting to mark a DVD+R or DVD+RW disc as a DVD-ROM disc.

To instruct your DVD home recorder to mark your DVD+R or DVD+RW discs as DVD-ROM, a special procedure must be followed. On a DVD+RW video recorder, you need to press a number of keys on the remote control. With a computer's DVD+R/DVD+RW drive, the use of a special utility is required to accomplish this.

Note that there are issues about whether bitsetting can take place before or after making a recording. See the following two links for more information on this subject:

Compatibility Bitsettings / Book Type Field -

http://www.dvdplusrw.org/Article.asp?mid=0&sid=2&aid=42

Apply Compatibility Bitsettings Using a DVD+R/+RW PC Drive -

"To change the compatibility bitsettings using a DVD+RW PC drive, you need a dedicated utility. Currently, there are several of these tools available. Of the DVD+RW drive manufacturers, Hewlett-Packard has publicly released a tool to change bitsettings on a DVD+RW disc (which can only be used with the HP DVD100/DVD200 drive), and Ricoh made a tool to change bitsettings for DVD+R discs (for usage with its MP5125 drive). The programs on this site are developed by users and can be used with all drives. We suggest you to use one of these (even if you own a HP or Ricoh DVD writer), because of their unmatched functionality. It is strongly advised not to install the HP utility on your system if you plan to use any of these, since it will most likely interfere with these tools and cause unexpected behaviour." -

http://www.dvdplusrw.org/article.asp?mid=0&sid=2&aid=44

BookType BitSetting FAQ How to Guide to set DVD+R/+R DL/RW to DVD-ROM - BitSetting DVD,BookType DVD,DVDDecrypter,NEC,Plextor,etc -

http://www.k-probe.com/bitsetting-booktype-faq.php

Other factors that can affect disc playability and/or compatibility

You should note that the compatibility of burned DVDs is commonly much more dependent on factors other than the state of the bitsetting.

The most common incompatibility problem is caused by improperly formatted DVDs that can play on a computer's DVD drive but not on a standalone home DVD player. The disc-burning utility Nero has often been blamed for being the cause of that problem.

The brand of DVD+R (or DVD-R) disc being used is also a known factor with regard to playability and compatibility. The most trusted and compatible brands are Verbatim, Maxell, TDK, and Mitsui (now known as MAM-A). It's certainly not a good idea to use unbranded, cheap discs.

It is also a known fact that discs burned at the slow speed of 1x can often be read by drives that won't read the same make and format of disc that has been burned at the slightly faster speed of 2x.

How audio and video files are encoded can also affect playback compatibility. The current rule of thumb in this regard is to keep the total bit rate to 7Mbit/s or lower, to use a Closed GOP setting for MPEG2 video, and always use a compressed option for the audio. E.g, Dolby Digital/AC3 audio compression is supported by all DVD players. Compressed audio can have a bit rate of between 128Kbit/s and 224Kbit/s, while uncompressed audio requires a bit rate of more than 1,500Kbit/s to achieve the virtually the same sound.

Using the Open or Closed GOP encoding

Question

I've noticed a lot of issues when files are encoded using Open GOP. Others have reported increased compatibility with Closed GOP over Open GOP. Compressor presets all use Closed GOP. What are the benefits of using Open GOP?

Answer

Group of Pictures (GOP) - http://en.wikipedia.org/wiki/Group_of_pictures

Using Closed GOP encoding has been recommended for projects distributed on DVD+R, DVD-R, (and other DVD recordable standards) because it is easier for a decoder to decode them. Using Open GOP encoding can give better quality video - especially at lower bit rates (under 5Mbit/s).