[FFmpeg-devel] [FFmpeg-cvslog] ffmpeg: pass first video AVFrame's side data to encoder

[James Almer]

On 3/22/2024 6:52 AM, Anton Khirnov wrote:
> Quoting Jan Ekström (2024-03-20 18:31:49)
>> ffmpeg | branch: master | Jan Ekström <jeebjp at gmail.com> | Mon Jan  9 20:52:30 2023 +0200| [8f4b173029aa9ecefb1370c954ef769664920d08] | committer: Jan Ekström
>>
>> ffmpeg: pass first video AVFrame's side data to encoder
>>
>> This enables further configuration of output based on the results
>> of input decoding and filtering in a similar manner as the color
>> information.
>>
>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8f4b173029aa9ecefb1370c954ef769664920d08
>> ---
>>
>>   fftools/ffmpeg_enc.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/fftools/ffmpeg_enc.c b/fftools/ffmpeg_enc.c
>> index c9a12af139..f01be1c22f 100644
>> --- a/fftools/ffmpeg_enc.c
>> +++ b/fftools/ffmpeg_enc.c
>> @@ -246,6 +246,21 @@ int enc_open(void *opaque, const AVFrame *frame)
>>           enc_ctx->colorspace             = frame->colorspace;
>>           enc_ctx->chroma_sample_location = frame->chroma_location;
>>   
>> +        for (int i = 0; i < frame->nb_side_data; i++) {
>> +            ret = av_frame_side_data_clone(
>> +                &enc_ctx->decoded_side_data, &enc_ctx->nb_decoded_side_data,
>> +                frame->side_data[i], AV_FRAME_SIDE_DATA_FLAG_UNIQUE);
> 
> I objected to this indiscriminate copying in a previous review.
> 
> There is no reason to expect side data to apply to the whole stream just
> because it happens to apply to the first frame. For many side data types
> it does not even make sense, as they are fundamentally per-frame.

So this would need to be handled by having decoders export global side 
data in decoded_side_data directly, so there's no need to take them from 
frames here (which would include per frame side data, like hdr10 and 
closed captions), right?