[FFmpeg-devel] [PATCH 2/3] avcodec/h264_metadata: filter parameter sets in packet side data

[James Almer]

On 4/22/2020 12:09 PM, James Almer wrote:
> Extradata included in packet side data is meant to replace the codec context
> extradata. So when muxing for example to MP4 without this change and if
> extradata is present in a packet side data, the result will be that the
> parameter sets present in keyframes will be filtered, but the parameter sets
> ultimately included in the avcC box will not.

Actually, unlike av1, the mp4 example doesn't apply for h264 and h265.
The mp4 muxer ignores new extradata in packet side data for those codecs.

Amended the commit message locally to remove it.

> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavcodec/h264_metadata_bsf.c | 50 ++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
> index d96a50dbf7..1347279b9d 100644
> --- a/libavcodec/h264_metadata_bsf.c
> +++ b/libavcodec/h264_metadata_bsf.c
> @@ -275,6 +275,52 @@ static int h264_metadata_update_sps(AVBSFContext *bsf,
>      return 0;
>  }
>  
> +static int h264_metadata_update_side_data(AVBSFContext *bsf, AVPacket *pkt)
> +{
> +    H264MetadataContext *ctx = bsf->priv_data;
> +    CodedBitstreamFragment *au = &ctx->access_unit;
> +    uint8_t *side_data;
> +    int side_data_size;
> +    int err, i;
> +
> +    side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
> +                                        &side_data_size);
> +    if (!side_data_size)
> +        return 0;
> +
> +    err = ff_cbs_read(ctx->cbc, au, side_data, side_data_size);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR, "Failed to read extradata from packet side data.\n");
> +        goto fail;
> +    }
> +
> +    for (i = 0; i < au->nb_units; i++) {
> +        if (au->units[i].type == H264_NAL_SPS) {
> +            err = h264_metadata_update_sps(bsf, au->units[i].content);
> +            if (err < 0)
> +                goto fail;
> +        }
> +    }
> +
> +    err = ff_cbs_write_fragment_data(ctx->cbc, au);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR, "Failed to write extradata into packet side data.\n");
> +        goto fail;
> +    }
> +
> +    side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, au->data_size);
> +    if (!side_data) {
> +        err = AVERROR(ENOMEM);
> +        goto fail;
> +    }
> +    memcpy(side_data, au->data, au->data_size);
> +
> +    err = 0;
> +fail:
> +    ff_cbs_fragment_reset(ctx->cbc, au);
> +    return err;
> +}
> +
>  static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *pkt)
>  {
>      H264MetadataContext *ctx = bsf->priv_data;
> @@ -286,6 +332,10 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *pkt)
>      if (err < 0)
>          return err;
>  
> +    err = h264_metadata_update_side_data(bsf, pkt);
> +    if (err < 0)
> +        goto fail;
> +
>      err = ff_cbs_read_packet(ctx->cbc, au, pkt);
>      if (err < 0) {
>          av_log(bsf, AV_LOG_ERROR, "Failed to read packet.\n");
>