[FFmpeg-devel] [PATCH v2 1/2] lavc/h2645_parse: Don't automatically remove nuh_layer_id > 0 packets

[Andriy Gelman]

On Fri, 13. Dec 22:18, Andriy Gelman wrote:
> On Thu, 05. Dec 22:15, Andriy Gelman wrote:
> > From: Andriy Gelman <andriy.gelman at 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.
> > 
> > Found-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> > Signed-off-by: Andriy Gelman <andriy.gelman at gmail.com>
> > ---
> >  libavcodec/cbs_h2645.c   | 3 +++
> >  libavcodec/h2645_parse.c | 7 +++----
> >  libavcodec/h2645_parse.h | 5 +++++
> >  libavcodec/hevc_parse.c  | 2 ++
> >  libavcodec/hevc_parser.c | 3 +++
> >  libavcodec/hevcdec.c     | 2 +-
> >  6 files changed, 17 insertions(+), 5 deletions(-)
> > 
> > diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
> > index 88fa0029cd6..ae32078f246 100644
> > --- a/libavcodec/cbs_h2645.c
> > +++ b/libavcodec/cbs_h2645.c
> > @@ -565,6 +565,9 @@ static int cbs_h2645_fragment_add_nals(CodedBitstreamContext *ctx,
> >          AVBufferRef *ref;
> >          size_t size = nal->size;
> >  
> > +        if (nal->nuh_layer_id > 0)
> > +            continue;
> > +
> >          // Remove trailing zeroes.
> >          while (size > 0 && nal->data[size - 1] == 0)
> >              --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;
> > +
> >      int skipped_bytes;
> >      int skipped_bytes_pos_size;
> >      int *skipped_bytes_pos;
> > diff --git a/libavcodec/hevc_parse.c b/libavcodec/hevc_parse.c
> > index dddb293df64..29dfd479f38 100644
> > --- a/libavcodec/hevc_parse.c
> > +++ b/libavcodec/hevc_parse.c
> > @@ -37,6 +37,8 @@ static int hevc_decode_nal_units(const uint8_t *buf, int buf_size, HEVCParamSets
> >  
> >      for (i = 0; i < pkt.nb_nals; i++) {
> >          H2645NAL *nal = &pkt.nals[i];
> > +        if (nal->nuh_layer_id > 0)
> > +            continue;
> >  
> >          /* ignore everything except parameter sets and VCL NALUs */
> >          switch (nal->type) {
> > diff --git a/libavcodec/hevc_parser.c b/libavcodec/hevc_parser.c
> > index b444b999550..87d5dba4f5e 100644
> > --- a/libavcodec/hevc_parser.c
> > +++ b/libavcodec/hevc_parser.c
> > @@ -202,6 +202,9 @@ static int parse_nal_units(AVCodecParserContext *s, const uint8_t *buf,
> >          H2645NAL *nal = &ctx->pkt.nals[i];
> >          GetBitContext *gb = &nal->gb;
> >  
> > +        if (nal->nuh_layer_id > 0)
> > +            continue;
> > +
> >          switch (nal->type) {
> >          case HEVC_NAL_VPS:
> >              ff_hevc_decode_nal_vps(gb, avctx, ps);
> > diff --git a/libavcodec/hevcdec.c b/libavcodec/hevcdec.c
> > index 8f1c162acee..bcd8e67944a 100644
> > --- a/libavcodec/hevcdec.c
> > +++ b/libavcodec/hevcdec.c
> > @@ -3077,7 +3077,7 @@ static int decode_nal_units(HEVCContext *s, const uint8_t *buf, int length)
> >  
> >          if (s->avctx->skip_frame >= AVDISCARD_ALL ||
> >              (s->avctx->skip_frame >= AVDISCARD_NONREF
> > -            && ff_hevc_nal_is_nonref(nal->type)))
> > +            && ff_hevc_nal_is_nonref(nal->type)) || nal->nuh_layer_id > 0)
> >              continue;
> >  
> >          ret = decode_nal_unit(s, nal);
> > -- 
> > 2.24.0
> 
> ping for both patches
> 

ping

-- 
Andriy