![]() ![]() ![]() The original drawing of the official document is If the protection missing ID ProtectionAbsent is 0, the ID has a 2-byte CRC check field The start bit of the copyright flag, the encoding is set to 0, and the decoding is ignoredįrame length: AAC raw data length + ADTS header length (protectionabsent = 1? 7: 9)īuffer fullness, 0x7FF indicates that it is a code stream with variable code rate Home, the encoding is set to 0, and decoding is ignoredĬopyright flag bit, encoding set to 0, decoding ignored Source ID, code set to 0, decoding ignored Private bit, set to 0, ignored during decoding Note that this is the serial number, not the sampling rate value. MPEG-4 sampling rate table serial number. Low complexity coding LC is commonly used. 0: Main Profile, 1:LC, 2: SSR, 3: reserved. Protection missing ID protectionabsent, 1 indicates no CRC, 0 indicates CRCĪAC encoding level, MPEG-4 Audio Object Type minus 1. MPEG version: 0 for MPEG-4, 1 for MPEG-2, mp4 is 0 One letter represents a field, and the number represents the bit length.ĪAAAAAAA AAAABCCD EEFFFFGH HHIJKLMM MMMMMMMM MMMOOOOO OOOOOOPP (QQQQQQQQ QQQQQQQQ)Ī-J is called ADTS fixed head and K-Q is called variable head. The format can be represented by the following letter sequence. ![]() ĪDTS Header is a fixed length of 7 bytes. ADTS stream formatĪDTS stream format is ADTS header plus AAC raw data. Therefore, ADIF is mainly used to store files on disk, and ADTS is mainly used for network flow of progressive transmission. The significant difference between ADIF and ADTS is that the coding information of the former has a fixed place, and the coding information of the latter is contained in every packet. The code stream organization formats include ADIF(Audio Data Interchange Format) and ADTS (Audio Data Transport Stream). Like other coding formats, AAC is only a data coding format. ![]()
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