How does CD-i audio work?
A Base Case CD-i player should be able to decode standard PCM audio as specified for CD-Audio, as well as a dedicated audio coding scheme called ADPCM, or Adaptive Delta Pulse Code Modulation. The difference with PCM is that audio is not stored individually per time segment, but that only the difference (delta) from the previous sample is recorded. This allows for a significant decrease in the used storage space on the disc, and hence in the datastream being read from the disc. When normal PCM CD-Audio would be used (which occupies all succesive sectors), this would not leave room for video or animations to be read without interrupting the audio playback. CD-i provides for 3 levels of ADPCM audio, all of which can be used either in mono or stereo: • CD-Audio PCM, 44.1 KHz, 16 bit, all sectors, up to 74 mintues • ADPCM Level A Stereo, 37.8 KHz, 8 bit, 1 in 2 sectors, up to 2.4 hours • ADPCM Level A Mono, 37.8 KHz, 8 bit, 1 in 4 sectors, up to 4.8 hours • ADPCM Level B Stereo, 37.8 KHz,
