Chiebot-Mirror/FFmpeg - FFmpeg - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Andreas Rheinhardt	bca4fef46a	avformat/matroskaenc: Use custom min timestamp Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>	3 years ago
Andreas Rheinhardt	eb325324aa	avformat/matroskaenc: Actually apply timestamp offset for Opus Matroska generally requires timestamps to be nonnegative, but there is an exception: Data that corresponds to encoder delay and is not supposed to be output anyway can have a negative timestamp. This is achieved by using the CodecDelay header field: The demuxer has to subtract this value from the raw (nonnegative) timestamps of the corresponding track. Therefore the muxer has to add this value first to write this raw timestamp. Support for writing CodecDelay has been added in FFmpeg commit `d92b1b1bab` and in Libav commit `a1aa37dd0b`. The former simply wrote the header field and did not apply any timestamp offsets, leading to desynchronisation (if one uses multiple tracks). The latter applied it at two places, but not at the one where it actually matters, namely in mkv_write_block(), leading to the same desynchronisation as with the former commit. It furthermore used the wrong stream timebase to convert the delay to the stream's timebase, as the conversion used the timebase from before avpriv_set_pts_info(). When the latter was merged in `82e4f39883`, it was only done in a deactivated state that still did not offset the timestamps when muxing due to "assertion failures and av sync errors". `a1aa37dd0b` made it definitely more likely to run into assertion failures (namely if the relative block timestamp doesn't fit into an int16_t). Yet all of the above issues have been fixed (in commits `962d631573`, `5d3953a5dc` and `4ebeab15b0`. This commit therefore enables applying CodecDelay, fixing ticket #7182. There is just one slight regression from this: If one has input with encoder delay where the first timestamp is negative, but the pts of the part of the data that is actually intended to be output is nonnegative, then the timestamps will currently by default be shifted to make them nonnegative before they reach the muxer; the muxer will then ensure that the shifted timestamps are retained. Before this commit, the muxer did not ensure this; instead the timestamps that the demuxer will output were shifted and if the first timestamp of the actually intended output was zero before shifting, then this unintentional shift just cancels the shift performed before the packet reached the muxer. (But notice that this only applies if all the tracks use the same CodecDelay, or the relative sync between tracks will be impaired.) This happens in the matroska-opus-remux and matroska-ogg-opus-remux FATE tests. Future commits will forward the information that the Matroska muxer has a limited capability to handle negative timestamps so that the shifting in libavformat can take advantage of it. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>	3 years ago
Andreas Rheinhardt	7bacef580f	avformat/matroskaenc: Only write DiscardPadding if nonzero It is possible for the trailing padding to be zero, namely e.g. if the AV_PKT_DATA_SKIP_SAMPLES side data is used for leading padding. Matroska supports this (use a negative DiscardPadding), but players do not; at least Firefox refuses to play such a file. So for now only write DiscardPadding if it is trailing padding and nonzero. The fate-matroska-ogg-opus-remux was affected by this. (I wish CodecDelay would not exist and DiscardPadding would be used to instead trim the codec delay away (with the Block timestamp corresponding to the time at which the actually output audio is output).) Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>	3 years ago
Andreas Rheinhardt	c0279e67f1	fate/matroska: Add tests for muxing with initial_padding Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>	3 years ago