Choosing bit-rates for video and audio
The video bit-rate affects both the video quality and the amount of video you can fit on a disc. High bit-rate video produces a higher-quality image and requires more disc space than lower bit-rate video.
There are several factors to consider when choosing a bit-rate:
Disc size: Larger disc capacities let you fit more video onto the disc or use higher bit-rates.
Type of video: If your video has fast action sequences, or scenes with random motion such as ripples on water, a low bit-rate may result in poor-quality video during those scenes.
Source video quality: MPEG compression works best with a high-quality source. If the original video is low quality — if it has video noise, scratches, and so on — you should either clean it up in a video editing application or choose a high bit-rate to prevent the quality from getting worse.
Slideshow and ROM data requirements: Slideshow source files and ROM data leave less space available for video.
Finally, the maximum bit-rate allowed by the DVD-Video format is 9.8 Mbps, which must be divided among the video, audio, and subtitle streams. Although DVD players play only one audio stream and one subtitle stream at a time, they read all the streams off the disc simultaneously, so you must take the bit-rates of all streams into account when calculating the bit-rate.
The following can help you to select the best bit-rate for a given video duration: