On Sat, 13 Jul 2019 at 22:33, Paul B Mahol <onemda@gmail.com> wrote:
NUT does not support that. What convinced you it does support it?
The NUT specification[1] talks specifically about per-frame metadata support: ---------------------------------------------- sm_data / side_data / meta_data This data structure is used both in frames for per frame side and metadata as well as info tags for metadata covering the whole file, a stream chapter or other. [...] Types of per frame side data: [...] "UserData<identifer here>" User specific side data, the "<identifer here>" should be replaced by a globally unique identifer of the project that uses/creates/understands the side data. For example "UserDataFFmpeg" ---------------------------------------------- The nut encoder[2] and decoder[3] code seems to fully handle this data already at AVPacket level, so either this metadata was (improperly?) named per-frame when it's actually per-packet, and some glue code is missing that mux and demux the metadata between frames <-> packet, or there's a bug somewhere. Also this feature request[4] asks for per-frame metadata in Matroska similarly to what it was done in NUT. This was all the evidence I could find but no full example. Cheers, Francesco [1] http://ffmpeg.org/~michael/nut.txt [2] https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/nutenc.c , write_sm_data() [3] https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/nutdec.c , read_sm_data() [4] https://github.com/cellar-wg/matroska-specification/issues/270