Commit Graph

11 Commits

Author SHA1 Message Date
wang-bin e285e22143 Use AV_INPUT_BUFFER_PADDING_SIZE instead of deprecated one
Signed-off-by: wm4 <wm4@nowhere>
2017-02-08 16:55:16 +01:00
wm4 9c12d54afa demux_mkv: passthrough BlockAdditions for libvpx alpha
Dumb but simple thing. Requires the FFmpeg libvpx decoder wrapper, as
its native decoder doesn't support alpha.
2017-01-31 14:48:10 +01:00
wm4 b14fac9afa build: replace some FFmpeg API checks with version checks
The FFmpeg versions we support all have the APIs we were checking for.
Only Libav missed them. Simplify this by explicitly checking for FFmpeg
in the code, instead of trying to detect the presence of the API.
2017-01-24 08:11:42 +01:00
wm4 0af5335383 Rewrite ordered chapters and timeline stuff
This uses a different method to piece segments together. The old
approach basically changes to a new file (with a new start offset) any
time a segment ends. This meant waiting for audio/video end on segment
end, and then changing to the new segment all at once. It had a very
weird impact on the playback core, and some things (like truly gapless
segment transitions, or frame backstepping) just didn't work.

The new approach adds the demux_timeline pseudo-demuxer, which presents
an uniform packet stream from the many segments. This is pretty similar
to how ordered chapters are implemented everywhere else. It also reminds
of the FFmpeg concat pseudo-demuxer.

The "pure" version of this approach doesn't work though. Segments can
actually have different codec configurations (different extradata), and
subtitles are most likely broken too. (Subtitles have multiple corner
cases which break the pure stream-concatenation approach completely.)

To counter this, we do two things:
- Reinit the decoder with each segment. We go as far as allowing
  concatenating files with completely different codecs for the sake
  of EDL (which also uses the timeline infrastructure). A "lighter"
  approach would try to make use of decoder mechanism to update e.g.
  the extradata, but that seems fragile.
- Clip decoded data to segment boundaries. This is equivalent to
  normal playback core mechanisms like hr-seek, but now the playback
  core doesn't need to care about these things.

These two mechanisms are equivalent to what happened in the old
implementation, except they don't happen in the playback core anymore.
In other words, the playback core is completely relieved from timeline
implementation details. (Which honestly is exactly what I'm trying to
do here. I don't think ordered chapter behavior deserves improvement,
even if it's bad - but I want to get it out from the playback core.)

There is code duplication between audio and video decoder common code.
This is awful and could be shareable - but this will happen later.

Note that the audio path has some code to clip audio frames for the
purpose of codec preroll/gapless handling, but it's not shared as
sharing it would cause more pain than it would help.
2016-02-15 21:04:07 +01:00
wm4 1f2a370a03 demux_mkv: refactor packet parsing
Makes it somewhat more uniform, and breaks up the awfully deep nesting.

This implicitly changes multiple small details, rather than only moving
code around. In particular, this computes the packet fields first and
parses them afterwards, which is needed for the next commit.
2015-02-05 21:52:07 +01:00
wm4 c54f0adacd demux: unbreak build with Libav
....
2014-11-03 22:30:07 +01:00
wm4 4e87ac8231 demux_mkv: implement audio skipping/trimming
This mechanism was introduced for Opus, and allows correct skipping of
"preroll" data, as well as discarding trailing audio if the file's
length isn't a multiple of the audio frame size.

Not sure how to handle seeking. I don't understand the purpose of the
SeekPreRoll element.

This was tested with correctness_trimming_nobeeps.opus, remuxed to mka
with mkvmerge v7.2.0. It seems to be correct, although the reported file
duration is incorrect (maybe a mkvmerge issue).
2014-11-03 20:20:28 +01:00
wm4 caaeb15318 demux: gracefully handle packet allocation failures
Now the packet allocation functions can fail.
2014-09-16 18:11:00 +02:00
wm4 758f8f7bd4 demux: always use AVPacket
This is a simplification, because it lets us use the AVPacket
functions, instead of handling the details manually.

It also allows the libavcodec rawvideo decoder to use reference
counting, so it doesn't have to memcpy() the full image data. The change
in av_common.c enables this.

This change is somewhat risky, because we rely on the following AVPacket
implementation details and assumptions:
- av_packet_ref() doesn't access the input padding, and just copies the
  data. By the API, AVPacket is always padded, and we violate this. The
  lavc implementation would have to go out of its way to make this a
  real problem, though.
- We hope that the way we make the AVPacket refcountable in av_common.c
  is actually supported API-usage. It's hard to tell whether it is.

Of course we still use our own "old" demux_packet struct, just so that
libav* API usage is somewhat isolated.
2014-08-25 00:46:26 +02:00
wm4 acd60736ef Remove stream_pts stuff
This was used by DVD/BD, but its usage was removed with one of the
previous commits.
2014-07-06 19:05:59 +02:00
wm4 a97256c1d5 demux: move packet functions to a separate source file 2014-07-05 17:07:14 +02:00