[FFmpeg-devel] [PATCH 2/3] cbs_av1: Support redundant frame headers

[James Almer]

On 11/4/2018 9:10 PM, Mark Thompson wrote:
> ---
> Includes support for using them when the normal frame header as been lost (try "-bsf:v filter_units=remove_types=3").
> 
> 
>  libavcodec/cbs_av1.c                 |  8 +++-
>  libavcodec/cbs_av1.h                 |  2 +
>  libavcodec/cbs_av1_syntax_template.c | 64 +++++++++++++++++++++++++---
>  3 files changed, 66 insertions(+), 8 deletions(-)
> 
> diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c
> index 1c49d90f51..b61b757f41 100644
> --- a/libavcodec/cbs_av1.c
> +++ b/libavcodec/cbs_av1.c
> @@ -996,7 +996,9 @@ static int cbs_av1_read_unit(CodedBitstreamContext *ctx,
>      case AV1_OBU_REDUNDANT_FRAME_HEADER:
>          {
>              err = cbs_av1_read_frame_header_obu(ctx, &gbc,
> -                                                &obu->obu.frame_header);
> +                                                &obu->obu.frame_header,
> +                                                obu->header.obu_type ==
> +                                                AV1_OBU_REDUNDANT_FRAME_HEADER);
>              if (err < 0)
>                  return err;
>          }
> @@ -1124,7 +1126,9 @@ static int cbs_av1_write_obu(CodedBitstreamContext *ctx,
>      case AV1_OBU_REDUNDANT_FRAME_HEADER:
>          {
>              err = cbs_av1_write_frame_header_obu(ctx, pbc,
> -                                                 &obu->obu.frame_header);
> +                                                 &obu->obu.frame_header,
> +                                                 obu->header.obu_type ==
> +                                                 AV1_OBU_REDUNDANT_FRAME_HEADER);
>              if (err < 0)
>                  return err;
>          }
> diff --git a/libavcodec/cbs_av1.h b/libavcodec/cbs_av1.h
> index b66a09c389..af9e88df71 100644
> --- a/libavcodec/cbs_av1.h
> +++ b/libavcodec/cbs_av1.h
> @@ -400,6 +400,8 @@ typedef struct CodedBitstreamAV1Context {
>      AVBufferRef          *sequence_header_ref;
>  
>      int seen_frame_header;
> +    uint8_t *frame_header;
> +    size_t   frame_header_size;
>  
>      int temporal_id;
>      int spatial_id;
> diff --git a/libavcodec/cbs_av1_syntax_template.c b/libavcodec/cbs_av1_syntax_template.c
> index e146bbf8bb..5649af841a 100644
> --- a/libavcodec/cbs_av1_syntax_template.c
> +++ b/libavcodec/cbs_av1_syntax_template.c
> @@ -1463,24 +1463,76 @@ static int FUNC(uncompressed_header)(CodedBitstreamContext *ctx, RWContext *rw,
>  }
>  
>  static int FUNC(frame_header_obu)(CodedBitstreamContext *ctx, RWContext *rw,
> -                                  AV1RawFrameHeader *current)
> +                                  AV1RawFrameHeader *current, int redundant)
>  {
>      CodedBitstreamAV1Context *priv = ctx->priv_data;
> -    int err;
> -
> -    HEADER("Frame Header");
> +    int start_pos, fh_bits, fh_bytes, err;
> +    const uint8_t *fh_start;
>  
>      if (priv->seen_frame_header) {
> -        // Nothing to do.
> +        if (!redundant) {
> +            av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid repeated "
> +                   "frame header OBU.\n");
> +            return AVERROR_INVALIDDATA;
> +        } else {
> +            GetBitContext fh;
> +            size_t k;
> +            int b;
> +
> +            HEADER("Redundant Frame Header");
> +
> +            init_get_bits(&fh, priv->frame_header,
> +                          priv->frame_header_size);
> +            for (k = 0; k < priv->frame_header_size; k++) {
> +                b = get_bits1(&fh);
> +                xf(1, frame_header_copy[k], b, b, b, 1, k);

This is making a lot of noise in the trace output for no real gain,
since it prints every single bit as its own line. Can you silence it?

> +            }
> +        }
>      } else {
> +        if (redundant)
> +            HEADER("Redundant Frame Header (used as Frame Header)");
> +        else
> +            HEADER("Frame Header");
> +
>          priv->seen_frame_header = 1;
>  
> +#ifdef READ
> +        start_pos = get_bits_count(rw);
> +#else
> +        start_pos = put_bits_count(rw);
> +#endif
> +
>          CHECK(FUNC(uncompressed_header)(ctx, rw, current));
>  
>          if (current->show_existing_frame) {
>              priv->seen_frame_header = 0;
>          } else {
>              priv->seen_frame_header = 1;
> +
> +            av_freep(&priv->frame_header);
> +
> +#ifdef READ
> +            fh_bits  = get_bits_count(rw) - start_pos;
> +            fh_start = rw->buffer + start_pos / 8;
> +#else
> +            // Need to flush the bitwriter so that we can copy its output,
> +            // but use a copy so we don't affect the caller's structure.
> +            {
> +                PutBitContext tmp = *rw;
> +                flush_put_bits(&tmp);
> +            }
> +
> +            fh_bits  = put_bits_count(rw) - start_pos;
> +            fh_start = rw->buf + start_pos / 8;
> +#endif
> +            fh_bytes = (fh_bits + 7) / 8;
> +
> +            priv->frame_header_size = fh_bits;
> +            priv->frame_header =
> +                av_mallocz(fh_bytes + AV_INPUT_BUFFER_PADDING_SIZE);
> +            if (!priv->frame_header)
> +                return AVERROR(ENOMEM);
> +            memcpy(priv->frame_header, fh_start, fh_bytes);

No way to use AVBufferRef for this?

I think i may have asked this before...

>          }
>      }
>  
> @@ -1528,7 +1580,7 @@ static int FUNC(frame_obu)(CodedBitstreamContext *ctx, RWContext *rw,
>  {
>      int err;
>  
> -    CHECK(FUNC(frame_header_obu)(ctx, rw, &current->header));
> +    CHECK(FUNC(frame_header_obu)(ctx, rw, &current->header, 0));
>  
>      CHECK(FUNC(byte_alignment)(ctx, rw));

Seems to work, so LGTM if the above can't be changed. Thanks!