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Audio Data Transport Stream (ADTS) is a format, used by MPEG TS or Shoutcast to stream audio, usually AAC.
AAAAAAAA AAAABCCD EEFFFFGH HHIJKLMM MMMMMMMM MMMOOOOO OOOOOOPP (QQQQQQQQ QQQQQQQQ)
Header consists of 7 or 9 bytes (without or with CRC).
|A||12||syncword 0xFFF, all bits must be 1|
|B||1||MPEG Version: 0 for MPEG-4, 1 for MPEG-2|
|C||2||Layer: always 0|
|D||1||protection absent, Warning, set to 1 if there is no CRC and 0 if there is CRC|
|E||2||profile, the MPEG-4 Audio Object Type minus 1|
|F||4||MPEG-4 Sampling Frequency Index (15 is forbidden)|
|G||1||private stream, set to 0 when encoding, ignore when decoding|
|H||3||MPEG-4 Channel Configuration (in the case of 0, the channel configuration is sent via an inband PCE)|
|I||1||originality, set to 0 when encoding, ignore when decoding|
|J||1||home, set to 0 when encoding, ignore when decoding|
|K||1||copyrighted stream, set to 0 when encoding, ignore when decoding|
|L||1||copyright start, set to 0 when encoding, ignore when decoding|
|M||13||frame length, this value must include 7 or 9 bytes of header length: FrameLength = (ProtectionAbsent == 1 ? 7 : 9) + size(AACFrame)|
|P||2||Number of AAC frames (RDBs) in ADTS frame minus 1, for maximum compatibility always use 1 AAC frame per ADTS frame|
|Q||16||CRC if protection absent is 0|
Usage in MPEG-TS
ADTS packet must be a content of PES packet. Pack AAC data inside ADTS frame, than pack inside PES packet, then mux by TS packetizer.
Usage in Shoutcast
ADTS frames goes one by one in TCP stream. Look for syncword, parse header and look for next syncword after.