AV1 specification [1] define 2 AV1 raw bitstreams storage
formats without containers:
- OBU in chapiter 5.2
- Annexb in chapiter 11.
Implement a detection function for the both cases mostly
by testing OBU forbidden, type, has_size_field and reserved bits.
For annexb case testing if temporal unit size, frame unit size and
obu length are valid. If they are check that the first OBU is
a temporal delimiter.
[1] https://aomediacodec.github.io/av1-spec/av1-spec.pdf
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8502>
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