In general, this warning can hint to actual bugs. We don't enable it
yet, because it would conflict with some unmerged code, and we should
check with clang too (this commit was done by testing with gcc).
This fixes the sample RA_missing_timestamps.mkv. Pretty funny how this
code got it almost right, but not quite, so it was broken all these
years. And then, after everyone stopped caring, someone comes and fixes
it. (By the way, I know absolutely nothing about realaudio.)
This fixes playback of the sample linked by FFmpeg ticket 2508. The fix
follows ffmpeg commit 6158a3b (although it's not exactly the same).
The problem here is that the file contains an apparently non-sense
DefaultDuration value. DefaultDuration for audio tracks is used to
derive PTS values for packets with no timestamps, like they can happen
with frames inside a laced block. So the first packet of a SimpleBlock
will have a correct PTS, while the PTS values of the following packets
are calculated using DefaultDuration, and thus are broken.
This leads to seemingly ok playback, but broken A/V sync. Not using the
DefaultDuration value will leave the PTS values of these packets unset,
and the audio decoder can derive them from the output instead.
The fix more or less uses a heuristic to detect the broken case: if the
sample rate is 8 KHz (Matroska default, can assume unset), and the codec
is AC3 (as the broken file did), don't use it. I'm not sure why this
should be done only for AC3, maybe the muxing application (mkvmerge
v4.9.1) has known issues with AC3. AC3 also doesn't support 8 KHz as
sample rate natively.
(By the way, I'm not sure why we should honor the DefaultDuration at all
for audio. It doesn't seem to be needed. You can't seek to these frames,
and decoders should always be able to produce perfect PTS values by
adding the duration of the decoded audio to the first PTS.)
Matroska has an output sample rate (OutputSamplingFrequency), which in
theory should be forced instead of whatever the decoder outputs. But it
appears no software (other than mplayer2 and mpv until now) actually
respects this. Even worse, there were broken files around, which played
correctly with (in theory) broken software, but not mplayer2/mpv. Hacks
were added to our code to play these files correctly, but they didn't
catch all cases.
Simplify this by doing what everyone else does, and always use the
decoder's sample rate instead. In particular, we try to handle all
sample rate issues like libavformat's Matroska demuxer does.
All demuxers make a reasonable effort to set packet timestamps, and thus
support correct-pts mode. This commit also implicitly switches
demux_rawvideo to correct-pts mode.
We still allow demuxers to disable correct-pts mode in theory.
Get rid of the strange and messy reliance on DEMUXER_TYPE_ constants.
Instead of having two open functions for the demuxer callbacks (which
somehow are both optional, but you can also decide to implement both...),
just have one function. This function takes a parameter that tells the
demuxer how strictly it should check for the file headers. This is a
nice simplification and allows more flexibility.
Remove the file extension code. This literally did nothing (anymore).
Change demux_lavf so that we check our other builtin demuxers first
before libavformat tries to guess by file extension.
Move codec_tags.h include to demux_mkv.c, because this is the only file
which still uses it.
Move new_sh_stream() to demux.h, because this is more proper.
Generally remove all accesses to demux_stream from all the code, except
inside of demux.c. Make it completely private to demux.c.
This simplifies the code because it removes an extra concept. In demux.c
it is reduced to a simple packet queue. There were other uses of
demux_stream, but they were removed or are removed with this commit.
Remove the extra "ds" argument to demux fill_buffer callback. It was
used by demux_avi and the TV pseudo-demuxer only.
Remove usage of d_video->last_pts from the no-correct-pts code. This
field contains the last PTS retrieved after a packet that is not NOPTS.
We can easily get this value manually because we read the packets
ourselves. Reuse sh_video->last_pts to store the packet PTS values. It
was used only by the correct-pts code before, and like d_video->last_pts,
it is reset on seek. The behavior should be exactly the same.
These separate arrays were used by the old demuxers and are not needed
anymore. We can simplify track switching as well.
One interesting thing is that stream/tv.c (which is a demuxer) won't
respect --no-audio anymore. It will probably work as expected, but it
will still open an audio device etc. - this is because track selection
is now always done with the runtime track switching mechanism. Maybe
the TV code could be updated to do proper runtime switching, but I
can't test this stuff.
Delete demux_avi, demux_asf, demux_mpg, demux_ts. libavformat does
better than them (except in rare corner cases), and the demuxers have
a bad influence on the rest of the code. Often they don't output
proper packets, and require additional audio and video parsing. Most
work only in --no-correct-pts mode.
Remove them to facilitate further cleanups.
The new wavpack packet format (see previous commit) doesn't work with
older libavcodec versions, so disable the new code in this case.
The version numbers are only approximate, since the libavcodec version
wasn't bumped with the wavpack change, but it's close enough.
Libav introduced a silent API breakage by changing what wavpack packets
the libavcodec decoder accepts. Originally the libavcodec codec accepted
Matroska-style wavpack packets. Libav commit 9b6f47c removed this
capability from the libavcodec code, and added code to libavformat's
Matroska demuxer to "rearrange" wavpack packets. Since demux_mkv still
sent Matroska-style packets, playback failed.
Fix this by "rearranging" packets in demux_mkv as well by copying
libavformat's code. (The best kind of fix.)
Tested with [CCCP]_Mega_Lossless_Audio_Test.mkv, as well as with a
sample generated by mkvmerge.
Playing Youtube videos often requires an additional seek to the end of
the file. This flushes the stream cache. The reason for the seek is
reading the cues (seek index). This poses the question why Google is
muxing its files in such a way, since nothing in Matroska mandates that
cues are located at the end of the file, but we want to handle this
situation better anyway.
The seek index is not needed for normal playback, only for seeking.
This commit changes header parsing such that the index is not read on
initialization in order to avoid the additional stream-level seek.
Instead, read the index on the first demuxer-level seek, when the seek
index is actually needed.
If the cues are at the beginning of the file, they are read immediately
as part of the normal header reading process. This commit changes
behavior only if cues are outside of the header (i.e. not in the area
between EBML header and clusters), and linked by a SeekHead. Other
level 1 elements linked by the SeekHead might still cause seeks to the
end of the file, although that seems to be rare.
Before this commit, the demuxer would in theory accept multiple cues
elements (and append its contents to the index in the order as
encountered during reading). According to the Matroska specification,
there can be only one cues element in the segment, so this seems like
an overcomplication.
Change it so that redundant elements are ignored, like with all other
unique header elements. This makes implementing deferred reading of the
cues element easier.
Nobody uses this, and this is an absolute waste of time. Even the user
who reported this turned out to have produced a sample manually.
Sample produced with:
wget http://diracvideo.org/download/test-streams/raw/vts/vts.LD-8Mb.drc
mkvmerge -o dirac.mkv vts.LD-8Mb.drc
mkvmerge writes a sort of broken aspect ratio. libavformat interprets it
as 1:1 PAR, while demux_mkv thinks this is a 1:1 DAR. Maybe libavformat
is more correct here.
This helps passing the channel layout correctly from decoder to audio
filter chain. (Because that part "reuses" the demuxer level codec
parameters, which is very disgusting.)
Note that ffmpeg stuff already passed the channel layout via
mp_copy_lav_codec_headers(). So other than easier dealing with the
demuxer/decoder parameters mess, there's no real advantage to doing
this.
Make the --channels option accept a channel map. Since simple numbers
map to standard layouts with the given number of channels, this is
downwards compatible. Likewise for demux_rawaudio.
These were found by the cppcheck and scan-build static analyzers. Most
of these aren't interesting (the 2 previous commits fix some interesting
cases found by these analyzers), and they don't nearly fix all warnings.
(Most of the unfixed warnings are spam, things MPlayer never cared
about, or false positives.)
This check was always false:
if (num == EBML_UINT_INVALID)
Fix it by using the proper type for the num variable.
This case actually doesn't really matter, and this is just for hiding
the warning and for being 100% correct.
Get rid of the 1-char subtitle type field. Use sh_stream->codec instead
just like audio and video do. Use codec names as defined by libavcodec
for simplicity, even if they're somewhat verbose and annoying.
Note that ffmpeg might switch to "ass" as codec name for ASS, so we
don't bother with the current silly "ssa" name.
mkv_track_t now references sh_stream directly, instead of using an ID.
Also remove all accesses to demux_stream (demuxer->video etc.).
Remove some slave-mode things on the way, like "ID_SID_..." messages.
Since demux_mkv queries the demuxer state when reading packets, track
switching is completely passive. Cycling etc. is done by the frontend.
As result, all track switching code can be removed.
Matroska files can contain multiple segments, which are literally
further Matroska files appended to the main file. They can be referenced
by segment linking.
While this is an extraordinarily useless and dumb feature, we support it
for the hell of it.
This is implemented by adding a further demuxer parameter for skipping
segments. When scanning for linked segments, each file is opened
multiple times, until there are no further segments found. Each segment
will have a separate demuxer instance (with a separate file handle
etc.).
It appears the Matroska spec. has an even worse feature for segments:
live streaming can completely reconfigure the stream by starting a new
segment. We won't add support for it, because there are 0 people on this
earth who think Matroska life streaming is a good idea. (As opposed to
serving Matroska/WebM files via HTTP.)
Matroska segment linking allows abusing Matroska files as playlists
without any actual video/audio/sub data, making files without any
clusters still useful for the frontend.
wm4
Stefano Pigozzi
Bin Jin
eng