AZID

The AZID application was designed to be a small AC3 decoder tool.

AC3 encoded audio is divided into frames. One frame gives 1536 samples of audio or 32ms of audio at 48kHz sampling rate. A single frame is divided into several sub-sections: ￭ syncronization ￭ bit stream information (BSI) ￭ 6 audio blocks ￭ auxilliary data (and CRC)

The BSI section contains information regarding the bitstream and the current frame. It contains information like samplerate, number of encoded channels, downmix-levels, dynamic compression types, program contents, etc.

The audio block contains the actual encoded audio. One block gives 256 samples (approx. 5.3ms at 48kHz). One audio block is atomic; the audio decoding operation is repeated for each of these six blocks. The specific details of this operation can be found in the A/52 spec.