[FFmpeg-devel] [PATCH v7 1/8] Add generic metadata injection using AV_PKT_DATA_METADATA_UPDATE

[Michael Niedermayer]

On Tue, Feb 25, 2025 at 04:01:14PM -0600, Romain Beauxis wrote:
> libavcodec/decode.c: intercept `AV_PKT_DATA_METADATA_UPDATE` packet
> extra data, attach them to the next decoded frame.
> 
> ---
>  libavcodec/decode.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> index cac7e620d2..96e2f0ce95 100644
> --- a/libavcodec/decode.c
> +++ b/libavcodec/decode.c
> @@ -97,6 +97,8 @@ typedef struct DecodeContext {
>      int lcevc_frame;
>      int width;
>      int height;
> +
> +    AVDictionary *pending_metadata;
>  } DecodeContext;
>  
>  static DecodeContext *decode_ctx(AVCodecInternal *avci)
> @@ -729,6 +731,8 @@ int attribute_align_arg avcodec_send_packet(AVCodecContext *avctx, const AVPacke
>  {
>      AVCodecInternal *avci = avctx->internal;
>      DecodeContext     *dc = decode_ctx(avci);
> +    const uint8_t *side_metadata;
> +    size_t size;
>      int ret;
>  
>      if (!avcodec_is_open(avctx) || !av_codec_is_decoder(avctx->codec))
> @@ -746,6 +750,14 @@ int attribute_align_arg avcodec_send_packet(AVCodecContext *avctx, const AVPacke
>          ret = av_packet_ref(avci->buffer_pkt, avpkt);
>          if (ret < 0)
>              return ret;
> +
> +        side_metadata = av_packet_get_side_data(avpkt, AV_PKT_DATA_METADATA_UPDATE, &size);
> +        if (side_metadata) {
> +            av_dict_free(&dc->pending_metadata);
> +            ret = av_packet_unpack_dictionary(side_metadata, size, &dc->pending_metadata);
> +            if (ret < 0)
> +                return ret;
> +        }
>      } else
>          dc->draining_started = 1;
>  
> @@ -815,6 +827,7 @@ fail:
>  int ff_decode_receive_frame(AVCodecContext *avctx, AVFrame *frame)
>  {
>      AVCodecInternal *avci = avctx->internal;
> +    DecodeContext     *dc = decode_ctx(avci);
>      int ret;
>  
>      if (!avcodec_is_open(avctx) || !av_codec_is_decoder(avctx->codec))
> @@ -887,6 +900,12 @@ int ff_decode_receive_frame(AVCodecContext *avctx, AVFrame *frame)
>          }
>      }
>  #endif
> +
> +    if (dc->pending_metadata) {
> +        av_dict_copy(&frame->metadata, dc->pending_metadata, AV_DICT_APPEND);
> +        av_dict_free(&dc->pending_metadata);
> +    }
> +
>      return 0;
>  fail:
>      av_frame_unref(frame);

Does this work correctly, if theres a delay/latency in the decoder ?

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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