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cartTutorials » CD and DVD Authoring Software a Safe Harbor blogHow 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. MPEG-2 or H.264 for Blu-ray disc?
When encoding video for Blu-ray disc, you can use MPEG-2 or H.264 encoding. MPEG-2 is used for DVD, but a much higher data rate is used for HD content on Blu-ray, so the image can be quite good. The benefit of H.264 is that at the lower data rates used to fit long programs on a disc, H.264 is more efficient than MPEG-2 and will produce a better quality. At higher data rates though, this advantage is less apparent. Considering that H.264 takes about 5x as long to encode as MPEG-2, you must decide whether the content is worth the extra hours of encoding time. If your workflow is such that you can do the encoding overnight, then H.264 becomes a more obvious choice, but when the production demands speed, MPEG-2 is quite suitable for most jobs. Either format is supported by all Blu-ray players per the official Blu-ray specification. How Should I Encode Audio for My DVD?
There are 3 kinds of audio that can be used when authoring DVDs. Dolby Digital (AC-3) – compressed audio with a very high quality, taking up very little space on the DVD. This allows you to encode the video at a higher data rate for better quality since you have more space available for video content. Dolby is the preferred choice for DVD audio. PCM – uncompressed audio, no different than a ".wav" file in your editing software. Two hours of PCM audio can take up over 1GB, which is a good portion of your DVD, leaving less room for quality video, so I avoid the PCM option when Dolby is available. MPEG – has space requirements similar to Dolby, but is NOT officially supported in the DVD specification. If your authoring software does not offer Dolby and you really need the space, MPEG audio may be an option. Note that most DVD players work just fine with MPEG audio, but since it’s not part of the "spec", DVD players are not required to play it. It would be rare to find an incompatible player, so not much of an issue for small runs, but I would not recommend it for mass-duplication. | About This BlogGet the most out of your video and post production tools with tricks and help tips from Jeff Pulera, Safe Harbor's resident video expert and the rest of our helpful staff.Newest Posts |
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