[FFmpeg-devel] [PATCH] avcodec/avpacket: add av_packet_remove_side_data()

[Andreas Rheinhardt]

James Almer:
> This helper removes a side data entry from the packet, maintaining the
> integrity and order of the remaining entries, if any.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> Missing APIChanges entry and version bump.
> 
> Couldn't find a place in the tree where it could be used right now, but
> it makes the API be more in line with the AVFrame one, so i decided to
> write it.
> 
>  libavcodec/avpacket.c | 24 ++++++++++++++++++++++++
>  libavcodec/packet.h   |  8 ++++++++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
> index 4801163227..61ea81698c 100644
> --- a/libavcodec/avpacket.c
> +++ b/libavcodec/avpacket.c
> @@ -367,6 +367,30 @@ uint8_t *av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType
>      return NULL;
>  }
>  
> +void av_packet_remove_side_data(AVPacket *pkt, enum AVPacketSideDataType type)
> +{
> +    int i, elems;
> +
> +    for (i = 0; i < pkt->side_data_elems; i++) {
> +        if (pkt->side_data[i].type != type)
> +            continue;
> +
> +        elems = pkt->side_data_elems - 1;
> +        av_freep(&pkt->side_data[i].data);
> +        pkt->side_data[i].size = 0;
> +
> +        if (i < elems) {
> +            memmove(&pkt->side_data[i], &pkt->side_data[i + 1],
> +                    (elems - i) * sizeof(*pkt->side_data));
> +        }
> +        if (!elems)
> +            av_freep(&pkt->side_data);
> +        pkt->side_data_elems = elems;
> +
> +        break;
> +    }
> +}
> +
>  const char *av_packet_side_data_name(enum AVPacketSideDataType type)
>  {
>      switch(type) {
> diff --git a/libavcodec/packet.h b/libavcodec/packet.h
> index 0a19a0eff3..6ce3c91c07 100644
> --- a/libavcodec/packet.h
> +++ b/libavcodec/packet.h
> @@ -595,6 +595,14 @@ int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
>  uint8_t* av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type,
>                                   int *size);
>  
> +/**
> + * Remove and free a side data entry of the given type.
> + *
> + * @param pkt packet
> + * @param type side data type to be removed
> + */
> +void av_packet_remove_side_data(AVPacket *pkt, enum AVPacketSideDataType type);

How about extending the functionality to optionally pass the side data
to the caller instead of freeing it? All it needs are two pointer
parameters for data and size. Then this function could be used to
simplify
https://ffmpeg.org/pipermail/ffmpeg-devel/2020-September/269319.html

- Andreas