AC3 specification
is defined and owned by Dolby. Dolby provides AC3 SDKs for commercial use.
However, the open source community has some open source AC3 codec and extends
the AC3 codec by adding BSID 9 and 10, which leads to the creation of
non-compliant bitstreams according to Dolby AC3 specification. Commercial Dolby
AC3 decoder will not support those non-compliant streams from open source
community.
Below are some
details about BSID equal to 9 and 10 in AC3 from open source community,
“AC3/BSID9 and AC3/BSID10 (DolbyNet) :
The ac3 frame header has, similar to the mpeg-audio header a version field. Normal ac3 is defined as bitstream id 8 (5 Bits, numbers are 0-15). Everything below 8 is still compatible with all decoders that handle 8 correctly. Everything higher are additions that break decoder compatibility.
For the samplerates 24kHz (00); 22,05kHz (01) and 16kHz (10) the BSID is 9
For the samplerates 12kHz (00); 11,025kHz (01) and 8kHz (10) the BSID is 10”
The ac3 frame header has, similar to the mpeg-audio header a version field. Normal ac3 is defined as bitstream id 8 (5 Bits, numbers are 0-15). Everything below 8 is still compatible with all decoders that handle 8 correctly. Everything higher are additions that break decoder compatibility.
For the samplerates 24kHz (00); 22,05kHz (01) and 16kHz (10) the BSID is 9
For the samplerates 12kHz (00); 11,025kHz (01) and 8kHz (10) the BSID is 10”
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