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

[James Almer]

On 9/9/2020 12:47 PM, Marton Balint wrote:
> 
> 
> On Tue, 8 Sep 2020, James Almer wrote:
> 
>> 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;
>> +    }
>> +}
> 
> Why not use the same algorightm that is used in av_frame_remove_side_data?
> Shorter and does not need memmove...

Frame side data and packet side data are different.

AVFrameSideData **side_data;

vs

AVPacketSideData *side_data;

You can also see the difference in the functions adding side data.