On 7/13/19, Francesco Pretto <ceztko@gmail.com> wrote:
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:
That is very vague and unspecific wording to claim such feature. And specification is misleading you. Anyway NUT specification was written much before introduction of frame metadata as we know it. So what you actually pointed out have nothing to do with frame metadata, but with updating stream metadata within new packet side data.
---------------------------------------------- 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 _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user
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