Adding support for parsing AlphaMode element in the Track header
and export that information as a metadata tag. This flag indicates
presence of alpha channel data in BlockAdditional element.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Matroska specification lists support for BlockAdditional element
which is not supported by ffmpeg's matroska parser. This patch
adds grammar definitions for parsing that element (and few other
related elements) and then puts the data in AVPacket.side_data
with new AVPacketSideDataType AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Support Matroska native formatting.
On demuxing prepend a Frame container atom (32bit big endian encoded
frame size and 'icpf' string).
On muxing remove it.
After much discussion and back-and-forth, we reached the conclusion
that matroska uses convergence_duration for subtitle duration because
a 32bit value isn't large enough to store the duration if sub-micro-second
timebases are used. Matroska may not be the only one that supports these
timebases, but it's certainly the only one that ffmpeg attempts to support
in this way.
The long term solution that we seemed to reach was that if we encounter
a matroska file with a sub-micro-second timebase, we should internally
scale it up to at least micro-second, and then duration can be used
normally. This suggests that on the encode side, we should not allow
generation of files with sub-micro-second timebases, but that's a separate
issue.
That being a non-trivial change, and the subtitle interoperability breakage
being very real, I'm re-submitting this small change for consideration.
In this diff, we make sure that duration is populated by the matroska
demuxer, and that convergence_duration is respected in matroskaenc and
srtenc, but that duration is used otherwise. This ends up being a strict
improvement - pipelines that use convergence duration are unchanged, and
ones that are currently broken due to the duration mismatch will start
working - except for the ones with the extreme timebases, but those were
already broken.
Signed-off-by: Philip Langdale <philipl@overt.org>
While not explicitly stated in the specs, the original author
has stated that S_TEXT/UTF-8 is expected to be text using Subrip
markup, but without Subrip in-band timing.
So, now that we have a decoder that conforms to this expectation,
let's use it.
Note that this change will impact tools that use libavformat. If
they expect srt subtitles to have CODEC_ID_TEXT, they must be
adjusted to expect CODEC_ID_SUBRIP. The actual content is, obviously,
unchanged.
Signed-off-by: Philip Langdale <philipl@overt.org>
According to its description, it is supposed to be the LCM of all the
frame durations. The usability of such a thing is vanishingly small,
especially since we cannot determine it with any amount of reliability.
Therefore get rid of it after the next bump.
Replace it with the average framerate where it makes sense.
FATE results for the wtv and xmv demux tests change. In the wtv case
this is caused by the file being corrupted (or possibly badly cut) and
containing invalid timestamps. This results in lavf estimating the
framerate wrong and making up wrong frame durations.
In the xmv case the file contains pts jumps, so again the estimated
framerate is far from anything sane and lavf again makes up different
frame durations.
In some other tests lavf starts making up frame durations from different
frame.
currently a overflow there should be impossible but future changes to
the code could easily introduce a bug that no longer limits the 2
values sufficiently so better protect it via av_assert.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Anton Khirnov
Vignesh Venkatasubramanian
Michael Niedermayer
Paul B Mahol
Dale Curtis
Diego Biurrun
Luca Barbato
Moritz Bunkus
Clément Bœsch
Philip Langdale