[FFmpeg-devel] [PATCH] avformat/utils: Avoid duplicating extradata from extract_extradata BSF

[Andreas Rheinhardt]

Andreas Rheinhardt:
> Instead move the extradata contained in packet side-data to its
> destination. This is possible because the side data already has zeroed
> padding.
> 
> Notice that the check for FF_MAX_EXTRADATA_SIZE has been dropped,
> because said constant is from libavcodec/internal.h. If libavcodec
> wanted to enforce this, it should do so in the extract_extradata BSF
> instead.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
>  libavformat/utils.c | 23 ++++++++---------------
>  1 file changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 807d9f10cb..63952e31a0 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -3567,9 +3567,6 @@ static int extract_extradata(AVStream *st, const AVPacket *pkt)
>      }
>  
>      while (ret >= 0 && !sti->avctx->extradata) {
> -        int extradata_size;
> -        uint8_t *extradata;
> -
>          ret = av_bsf_receive_packet(sti->extract_extradata.bsf, pkt_ref);
>          if (ret < 0) {
>              if (ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
> @@ -3577,19 +3574,15 @@ static int extract_extradata(AVStream *st, const AVPacket *pkt)
>              continue;
>          }
>  
> -        extradata = av_packet_get_side_data(pkt_ref, AV_PKT_DATA_NEW_EXTRADATA,
> -                                            &extradata_size);
> -
> -        if (extradata) {
> -            av_assert0(!sti->avctx->extradata);
> -            if ((unsigned)extradata_size < FF_MAX_EXTRADATA_SIZE)
> -                sti->avctx->extradata = av_mallocz(extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
> -            if (!sti->avctx->extradata) {
> -                av_packet_unref(pkt_ref);
> -                return AVERROR(ENOMEM);
> +        for (int i = 0; i < pkt_ref->side_data_elems; i++) {
> +            AVPacketSideData *side_data = &pkt_ref->side_data[i];
> +            if (side_data->type == AV_PKT_DATA_NEW_EXTRADATA) {
> +                sti->avctx->extradata      = side_data->data;
> +                sti->avctx->extradata_size = side_data->size;
> +                side_data->data = NULL;
> +                side_data->size = 0;
> +                break;
>              }
> -            memcpy(sti->avctx->extradata, extradata, extradata_size);
> -            sti->avctx->extradata_size = extradata_size;
>          }
>          av_packet_unref(pkt_ref);
>      }
> 
Will apply tomorrow unless there are objections.

- Andreas