How Much Video Can I Fit on a DVD?
Video files must be compressed to the MPEG-2 format to meet the DVD specification. The amount of compression can vary, and is determined by the length of the program, as the compressed content must fit the available space on the DVD.
At the highest quality setting, a standard 4.7GB DVD can hold 1 hour of video, but at a medium quality setting, the same DVD can hold 2 hours of video. If quality is not that important for your application, you can even fit 3 hours or more on a single DVD by compressing the material at a lower data rate.
You will want to specify Dolby Digital (AC-3) audio in your DVD encoding settings, as this uses much less space than the standard “PCM” uncompressed audio, leaving more room for higher quality (less compressed) video content.
While an encoding bitrate of 8.0 is about the maximum allowed for the video, I don’t recommend going above 7.0 as it can cause playability issues with some players, and any quality difference at those rates is negligible.
A good rule of thumb to figure the encoding data rate is 4.5 for 120 minutes, 6.0 for 90 minutes, and 7.0 for 60 minutes or less. An easy formula to figure the proper rate is 560/minutes, assuming Dolby Digital audio encoding.