[FFmpeg-user] Adding user-defined SEI messages thru libavcodec/libx264

[lyncher at sapo.pt]

On 01-11-2014 9:14, SF wrote:
> I am searching a way to insert private SEI messages before each picture when encoding with x264. As far as i see from the libx264.c code, it is not supported up to now.
> Am i correct ?
>
> If yes, i am willing to push patch to support this, but do you have a preferred way to do this (ie thru medata field of AVFrame ? thru sidedata of AVFrame ? ...)
>

Hi,
I was wondering if there's already a solution/workaround to this 
unanswered question...?

I'm looking into the examples (remuxing.c, demuxing_decoding.c) and 
running with a file which has SEI messages (Closed Captioning) and they 
are not loaded into AVPacketSideData.data.

The demuxing_decoding.c example uses the old avcodec API 
(avcodec_decode_video2/avcodec_decode_audio4) but there's also the note: 
"The new API does not handle subtitles yet."

Is it possible to have ffmpeg (3.4.1) reading/writing SEI messages 
containing AV_PKT_DATA_A53_CC?
What would be be the procedure?

Thank you
lyncher