[FFmpeg-devel] [PATCH] libavcodec/hevc_mp4toannexb_bsf: insert extradata before non-AUD unit

[Xiang, Haihao]

On Thu, 2022-03-17 at 14:35 +0800, Xiang, Haihao wrote:
> From: Haihao Xiang <haihao.xiang at intel.com>
> 
> It is possible that an IRAP frame in input AVPacket contains VPS, SPS
> and PPS, and these headers should take effect. However the prepended
> extradata might override these headers. This patch inserts extradata
> before non-AUD unit, hence VPS, SPS and PPS from the input AVPacket will
> take effect if they are present.
> 
> This should fix #7799
> 
> Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>
> ---
>  libavcodec/hevc_mp4toannexb_bsf.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/hevc_mp4toannexb_bsf.c
> b/libavcodec/hevc_mp4toannexb_bsf.c
> index 790dfb0394..77551ba221 100644
> --- a/libavcodec/hevc_mp4toannexb_bsf.c
> +++ b/libavcodec/hevc_mp4toannexb_bsf.c
> @@ -124,6 +124,7 @@ static int hevc_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *out)
>  
>      int got_irap = 0;
>      int i, ret = 0;
> +    int prev_nalu_is_aud = 0, extradata_offset = 0;
>  
>      ret = ff_bsf_get_packet(ctx, &in);
>      if (ret < 0)
> @@ -169,14 +170,21 @@ static int hevc_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *out)
>  
>          prev_size = out->size;
>  
> +        if (prev_nalu_is_aud)
> +            extradata_offset = prev_size;
> +
>          ret = av_grow_packet(out, 4 + nalu_size + extra_size);
>          if (ret < 0)
>              goto fail;
>  
> -        if (extra_size)
> -            memcpy(out->data + prev_size, ctx->par_out->extradata,
> extra_size);
> +        if (extra_size) {
> +            memmove(out->data + extradata_offset + extra_size, out->data +
> extradata_offset, prev_size - extradata_offset);
> +            memcpy(out->data + extradata_offset, ctx->par_out->extradata,
> extra_size);
> +        }
> +
>          AV_WB32(out->data + prev_size + extra_size, 1);
>          bytestream2_get_buffer(&gb, out->data + prev_size + 4 + extra_size,
> nalu_size);
> +        prev_nalu_is_aud = nalu_type == HEVC_NAL_AUD;
>      }
>  
>      ret = av_packet_copy_props(out, in);

User verified this patch works (https://trac.ffmpeg.org/ticket/7799#comment:19)
and is asking to merge the patch (See 
https://trac.ffmpeg.org/ticket/7799#comment:21). Is there any comment ?

Thanks
Haihao