AAC codec registration
Description
The Advanced Audio Coding (AAC) audio codec, specified in ISO/IEC 14496-3.
An AAC bitstream can have either of two formats:
- AAC (raw), where packets contain raw AAC frames (syntax element
raw_data_block()) as defined in ISO/IEC 14496-3 Section 4.4.2.1. Here, codec metadata is provided out-of-band. - ADTS, where packets contain ADTS frames as defined in ISO/IEC 14496-3 Section 1.A.3.2. Here, codec metadata is provided in-band in each ADTS frame header.
All packets within the bitstream must have the same format.
Codec ID
'aac'EncodedPacket data
If the bitstream is in the AAC (raw) format, the packet's data must be a raw AAC frame (syntax element raw_data_block()) as defined in ISO/IEC 14496-3 Section 4.4.2.1.
If the bitstream is in the ADTS format, the packet's data must be an ADTS frame as defined in ISO/IEC 14496-3 Section 1.A.3.2.
EncodedPacket type
The packet's type is always 'key'.
AudioDecoderConfig codec string
The following fully qualified codec strings are recognized:
'mp4a.40.2'— MPEG-4 AAC-LC'mp4a.40.02'— MPEG-4 AAC-LC (leading zero for Aud-OTI compatibility)'mp4a.40.5'— MPEG-4 HE-AAC v1 (AAC-LC + SBR)'mp4a.40.05'— MPEG-4 HE-AAC v1 (leading zero for Aud-OTI compatibility)'mp4a.40.29'— MPEG-4 HE-AAC v2 (AAC-LC + SBR + PS)'mp4a.67'— MPEG-2 AAC-LC
AudioDecoderConfig description
If the bitstream is in the AAC (raw) format, description must be an AudioSpecificConfig as defined in ISO/IEC 14496-3 Section 1.6.2.1.
If the bitstream is in the ADTS format, description must be undefined.