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

[Andriy Gelman]

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

Thanks
-- 
Andriy