Le lun. 17 févr. 2025 à 13:10, Lynne <d...@lynne.ee> a écrit : > > On 17/02/2025 17:19, Romain Beauxis wrote: > > libavcodec/decode.c: intercept `AV_PKT_DATA_METADATA_UPDATE` packet extra > > data, > > attach them to the next decoded frame. > > > > The metadata needs to be cached because there is no guarantee that each > > packet > > will generate a decoded frame immediately. > > > > `AV_PKT_DATA_METADATA_UPDATE` does not seem used in `libavcodec` at the > > moment > > so regression risks seem low. > > > > This generic mechanism could be reused to support more in-band metadata > > update > > in the future. > > Much cleaner than before, thanks.
Thanks for the guidance! > Which packets will not generate a decoded frame immediately? When it > comes to audio, all of them should output something immediately. > The code is correct, metadata updates could occur on B-frames in video. > Just wondering. I was working from memory about ogg/flac but got it wrong: flac frames map to ogg packets BUT they can span page boundaries: > * Native FLAC audio frames appear as subsequent packets in the stream. Each > packet corresponds to one FLAC audio frame. The first byte of each packet > serves as the packet type. >. Since audio packets are native FLAC frames, > this first byte will be always 0xFF according to the native FLAC format > specification. > * The last page is marked 'end of stream' in the page flags. > * FLAC packets may span page boundaries. Source: https://xiph.org/flac/ogg_mapping.html This is a bit confusing, though. At any rate, however, in the current implementation, flac ogg packet headers are still exported by the demuxer and later ignored by the decoder. These packets would not generate an audio frame. I'm happy to work on further improvement on this as discussed. Then we could consider un-caching the metadata. -- Romain _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
