lavc/vvc: Error if SPS ID is duplicated within CVS

Key line from the spec is:

"All SPS NAL units with a particular value of sps_seq_parameter_set_id
in a CVS shall have the same content."

Prior to this patch, the VVC decoder's behaviour on encountering a
duplicated SPS ID (within the entire bitstream, not restricted to
a CVS) was simply to replace the entry in the SPS lookup table with the
new data.  Illegal bitstreams with multiple SPSs in the same CVS sharing
an ID but differing elsewhere could cause all manner of issues.

The patch tracks which SPS IDs have been used in the given CVS using the
new sps_id_used field of VVCParamSets.  If it encounters an SPS with an
ID already in use and whose content differs from the previous SPS, it
throws an AVERROR_INVALIDDATA.

Signed-off-by: Frank Plowman <post@frankplowman.com>

0 files changed, 0 insertions, 0 deletions