MPEG-4: FlasK MPEG/Divx's Improved Coding

Data Rate Vs. Video Quality

Top-notch video quality at a relatively high data rate and resolution.

Despite the fast motion, this sequence still demonstrates high video quality - thanks to the new Divx codec.

Potential video quality at a specified data rate, with the actual data rate consisting of combined video and audio data, is a very interesting and important topic. Generally, a video data rate of 1500 kBit/s (equivalent to 187.5 kByte/s) and an audio data rate of 128 kBit/s (equivalent to 16 kByte/s) produce quite high-quality video. Unfortunately, at a total data rate of 203.5 kByte/s (203.5=187.5+16), barely 55 minutes of video will fit on your average blank CD-ROM with 650 MB storage capacity.

Using a 700 MB medium only increases the time by less than 4 minutes, making for a total of 58 minutes of video. The options for reducing data volume have been thoroughly discussed in our previous article "MPEG-4: Optimizing Picture Quality and Data Rates ".

In general, a slight reduction in your resolution while maintaining the same data rate will improve your video quality considerably.

Another option is to split the film up into several CD-ROMs. This latter method keeps the resolution and the video quality high, while the solution with lower resolution fits on one CD-ROM.

Best compromise between video quality and resolution - using the displayed data rate allows you to copy DVD sequences to CD-ROM.