[Bug 732266] vaapidecode: h264: add support for decoding SVC base layers only

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=732266

--- Comment #36 from sreerenj <bsreerenj at gmail.com> ---
(In reply to Orestis Floros from comment #34)
> Created attachment 358103 [details] [review]
> libs: decoder: h264: decode SVC base view only
> 
> (In reply to sreerenj from comment #33)
> > Review of attachment 358041 [details] [review] [review]:

> 
> > @@ +1941,3 @@
> >    GST_DEBUG ("decode subset SPS");
> >
> > +  /* Don't replace. Could overwrite needeed SPS's. */
> >
> > Bit confused with this comment. I understood that in base-only case, we
> > don't have to store the subset_sps. But when can this "Overwrite needed sps"
> > happen?
> 
> spec says:
> 
> > NOTE 7 ? A decoder must be capable of simultaneously storing the contents of the sequence parameter sets and subset sequence
> parameter sets for all values of seq_parameter_set_id. The content of the
> sequence parameter set with a particular value of
> seq_parameter_set_id is overwritten when a new sequence parameter set NAL
> unit with the same value of seq_parameter_set_id is
> received, and the content of the subset sequence parameter set with a
> particular value of seq_parameter_set_id is overwritten when
> a new subset sequence parameter set NAL unit with the same value of
> seq_parameter_set_id is received.
> 

Here the spec clearly saying that "SPS should be replaced by another SPS with
the same id" and "SUBSET_SPS should be replaced by another SUBSET_SPS with the
same id". 

Am I misinterpreting something here? :)



> Eg in SVCHS-2.264:
> nalu type=7 has seq_parameter_set_id=0 and next nalu type=15 has
> seq_parameter_set_id=0.


Hm, I am afraid we need some serious changes in
codecparser/videoparser/decoders since the GstH264NalParser is not keeping
separate array for sps and subset sps.

Is it the only sample which exhibiting this behavior?

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