To clear things up and avoid confusion... I am not Mark White. I did help Mark with the MpegDec project, but only in small ways -- beta testing, icon design, and web design/hosting.
It's too bad MpegDec has that MP2 bug. (There were screeches and other noises in the AIFF, when I tested it yesterday on my G4 in Classic.) MpegDec seems to be much faster at conversion than MPEG Audio Coder. I had forgotten that SoundApp will do the conversion on 68k Macs -- and quickly, IIRC. Thanks, Norman Franke.
The big trick to Cinepak is keyframes. With MJPEG, every frame is a keyframe and is encoded independently of other frames. With Cinepak, Video, Sorenson, and MPEG codecs, there are keyframes and intraframes. Intraframes only contain data for changes in the frame instead of the whole frame. So... if you set keyframes to "every 15 frames", then it can utilize infraframe compression to more efficiently use the desired data rate. If you encode Cinepak without setting keyframes, it will make every frame a keyframe, then the benefits of intraframe compression get lost -- which is probably why MJPEG looks comparable or better than Cinepak at the same bit rate.
It's too bad MpegDec has that MP2 bug. (There were screeches and other noises in the AIFF, when I tested it yesterday on my G4 in Classic.) MpegDec seems to be much faster at conversion than MPEG Audio Coder. I had forgotten that SoundApp will do the conversion on 68k Macs -- and quickly, IIRC. Thanks, Norman Franke.
The big trick to Cinepak is keyframes. With MJPEG, every frame is a keyframe and is encoded independently of other frames. With Cinepak, Video, Sorenson, and MPEG codecs, there are keyframes and intraframes. Intraframes only contain data for changes in the frame instead of the whole frame. So... if you set keyframes to "every 15 frames", then it can utilize infraframe compression to more efficiently use the desired data rate. If you encode Cinepak without setting keyframes, it will make every frame a keyframe, then the benefits of intraframe compression get lost -- which is probably why MJPEG looks comparable or better than Cinepak at the same bit rate.