On Mon, 02. Dec 07:50, Andreas Rheinhardt wrote:
> On Mon, Dec 2, 2019 at 3:49 AM Andriy Gelman <andriy.gel...@gmail.com>
> wrote:
>
> > From: Andriy Gelman <andriy.gel...@gmail.com>
> >
> > HEVC standard supports multi-layer streams (ITU-T H.265 02/2018 Annex
> > F). Each NAL unit belongs to a particular layer defined by nuh_layer_id
> > in the header.
> >
> > Currently, all NAL units that do not belong to a base layer are
> > automatically removed in ff_h2645_packet_split(). Some data may
> > therefore be lost when future filters/decoders are designed to support
> > multi-layer streams.
> >
> > A better approach is to forward nuh_layer_id > 0 packets and let blocks
> > down the chain decide how to process them. The condition to remove
> > packets has been moved to hevcdec and cbs bsf where such packets are
> > currently not supported.
> > ---
> > libavcodec/cbs_h2645.c | 3 +++
> > libavcodec/h2645_parse.c | 7 +++----
> > libavcodec/h2645_parse.h | 5 +++++
> > libavcodec/hevc_parse.c | 2 ++
> > libavcodec/hevc_parser.c | 2 ++
> > libavcodec/hevcdec.c | 2 +-
> > 6 files changed, 16 insertions(+), 5 deletions(-)
> >
> > diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
> > index 88fa0029cd6..9f89f1c5a55 100644
> > --- a/libavcodec/cbs_h2645.c
> > +++ b/libavcodec/cbs_h2645.c
> > @@ -562,6 +562,9 @@ static int
> > cbs_h2645_fragment_add_nals(CodedBitstreamContext *ctx,
> >
> > for (i = 0; i < packet->nb_nals; i++) {
> > const H2645NAL *nal = &packet->nals[i];
> > + if (nal->nuh_layer_id > 0)
> > + continue;
> > +
> >
>
> Mixed declaration and code. But, as James has already said: cbs should not
> drop higher layers by default.
>
>
> > AVBufferRef *ref;
> > size_t size = nal->size;
> >
> > diff --git a/libavcodec/h2645_parse.c b/libavcodec/h2645_parse.c
> > index 4808f79a67f..0f3343004f9 100644
> > --- a/libavcodec/h2645_parse.c
> > +++ b/libavcodec/h2645_parse.c
> > @@ -292,23 +292,22 @@ static int get_bit_length(H2645NAL *nal, int
> > skip_trailing_zeros)
> > static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)
> > {
> > GetBitContext *gb = &nal->gb;
> > - int nuh_layer_id;
> >
> > if (get_bits1(gb) != 0)
> > return AVERROR_INVALIDDATA;
> >
> > nal->type = get_bits(gb, 6);
> >
> > - nuh_layer_id = get_bits(gb, 6);
> > + nal->nuh_layer_id = get_bits(gb, 6);
> > nal->temporal_id = get_bits(gb, 3) - 1;
> > if (nal->temporal_id < 0)
> > return AVERROR_INVALIDDATA;
> >
> > av_log(logctx, AV_LOG_DEBUG,
> > "nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
> > - nal->type, hevc_nal_unit_name(nal->type), nuh_layer_id,
> > nal->temporal_id);
> > + nal->type, hevc_nal_unit_name(nal->type), nal->nuh_layer_id,
> > nal->temporal_id);
> >
> > - return nuh_layer_id == 0;
> > + return 1;
> > }
> >
> > static int h264_parse_nal_header(H2645NAL *nal, void *logctx)
> > diff --git a/libavcodec/h2645_parse.h b/libavcodec/h2645_parse.h
> > index 2acf882d3da..3e47f86c53b 100644
> > --- a/libavcodec/h2645_parse.h
> > +++ b/libavcodec/h2645_parse.h
> > @@ -56,6 +56,11 @@ typedef struct H2645NAL {
> > */
> > int temporal_id;
> >
> > + /*
> > + * HEVC only, identifier of layer to which nal unit belongs
> > + */
> > + int nuh_layer_id;
> > +
> >
>
> You might want to add a commit on top of that to reorder the H2645NAL
> entries so that the size doesn't increase.
>
Thanks for looking over patch.
I'll update and resend.
--
Andriy
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