This code was once part of subreader.c, then traveled to libass, and now
made its way back to the fork of the fork of the original code, MPlayer.
It works pretty much the same as subreader.c, except that we have to
concatenate some packets to do auto-detection. This is rather annoying,
but for all we know the actual source file could be a binary format.
Unlike subreader.c, the iconv context is reopened on each packet. This
is simpler, and with respect to multibyte encodings, more robust.
Reopening is probably not a very fast, but I suspect subtitle charset
conversion is not an operation that happens often or has to be fast.
Also, this auto-detection is disabled for microdvd - this is the only
format we know that has binary data in its packets, but is actually
decoded to text. FFmpeg doesn't really allow us to solve this properly,
because a) the input packets can be binary, and b) the output will be
checked whether it's UTF-8, and if it's not, the output is thrown away
and an error message is printed. We could just recode the decoded
subtitles before sd_ass if it weren't for that.
demux_libass.c allows us to make subtitle format detection part of the
normal file loading process. libass has no probe function, but trying to
load the start of a file (the first 4 KB) is good enough. Hope that
libass can even handle random binary input gracefully without printing
stupid log messages, and that the libass parser doesn't accept too many
non-ASS files as input.
This doesn't handle the -subcp option correctly yet. This will be fixed
later.
The default correct-pts mode depended on which demuxer was opened last.
Often this is the subtitle demuxer. The correct-pts mode should be
decided on the demuxer for video instead.
subreader.c (before this commit renamed to demux_subreader.c) was
special cased to the -sub option. The plan is using the normal demuxer
codepath for all subtitle formats (so we can prefer libavformat demuxers
for most formats).
There are some subtle changes. The probe size is restricted to 32 KB
(instead of unlimitted + giving up after 100 lines of input). For
formats like MicroDVD, the video FPS isn't used anymore, because it's
not available on the subtitle demuxer level. Instead, hardcode it to
23.976 FPS (libavformat seems to do the same). The user can probably
still use -sub-fps to fix the timing. Checking the file extension for
".utf"/".utf8"/".utf-8" is simply removed (seems worthless, was in the
way, and I've never seen this anywhere).
Simpler, reduces the amount of copying.
We still have to malloc+memcpy the probe buffer though, because padding
with FF_INPUT_BUFFER_PADDING_SIZE is required by libavformat.
stream_read_unbuffered() can sometimes return negative values on error.
Change that to return 0 - the negative values are nowhere used anyway.
If distinguishing errors and EOF is really needed, a flag could be added
instead.
This also fixes the stream_read_partial() call in cache.c, which assumes
the return values is always >= 0.
Actually check the newly added text for whitespace, and not the
uninitialized buffer after it. Also, if an even is only whitespace,
don't add it at all.
sd_ass contains some code that treats subtitle events with duration 0
specially, and adjust their duration so that they will disappear with
the next event.
This is most likely not needed anymore. Some subtitle formats allow
omitting the duration so that the event is visible until the next one,
but both subreader.c as well as libavformat subtitle demuxers already
handle this.
Subtitles embedded in mp4 files (movtext) used to trigger this code. But
these files appear to export subtitle duration correctly (at least
libavcodec's movtext decoder is using this assumption). Since commit
6dbedd2 changed demux_lavf to actually copy the packet duration field,
the code removed with this commit isn't needed anymore for correct
display of movtext subtitles. (The change in sd_movtext is for dropping
empty subtitle events, which would now be "displayed" - libavcodec does
the same.)
On the other hand, this code incorrectly displayed hidden events in .srt
subtitles. See for example the first event in SubRip_capability_tester.srt
(part of FFmpeg's FATE). These intentionally have a duration of 0, and
should not be displayed. (As of with this commit, they are still
displayed in external .srt subs because of subreader.c hacks.)
However, we can't be 100% sure that this code is really unneeded, so
just comment the code. Hopefully it can be removed if there are no
regressions after some weeks or months.
Querying this caused the cache to block and wait. Some parts of the
frontend (like progress bar) call this very often, so cache performance
was ruined in these cases.
Also print a message in -v mode when the cache is blocked for a
STREAM_CTRL. This should make debugging similar issues easier.
Currently, we are filtering libavformat style ASS packets by checking
whether they are prefixed "Dialogue: ". Unfortunately, comment packets
are demuxed too. These start with "Comment: ", so they are not caught.
Change the filtering, and use the codec ID instead. libavformat uses
"ssa" as codec ID for ASS subtitles, while mpv uses "ass". Also, at
least FFmpeg will change the ASS packet format to the same format mpv
and Matroska use, and identify these with "ass" as codec ID, so this is
works out nicely.
Some of this (fixing timing) is now done in dec_sub.c (although it's
not active for subreader.c code yet - this will be fixed when
subreader.c subs are read through a demuxer wrapper).
Another reason to remove this is that this code doesn't do much good
anymore. libass does handle overlap, and trying to fold overlapping
lines into single subtitle events will prevent libass from handling
this properly.
This fixes the -subfps option (which unfortunately is still useful),
and fixes minor annoying timing errors (which unfortunately still
happen).
Note that none of these affect ASS or image subtitles. ASS is specially
handled: libass loads subtitles as ASS_Track. There are no actual
packets passed around, and sd_ass just uses the ASS_Track.
Disable the --sub-no-text-pp option. It's misleading now and always was
completely useless.
If a subtitle is external, read it completely and add all subtitle
events in advance when the subtitle track is selected. This is done
for text subtitles only. (Note that subreader.c and subtitles loaded
with libass are different and don't have anything to do with this
commit.)
Seems like a completely unnecessary complication. Instead, always add a
1 byte padding (could be extended if a caller needs it), and clear it.
Also add some documentation. There was some, but it was outdated and
incomplete.
Don't print the ffmpeg context pointer as %p. This is usually useless
and confusing. Prefix all messages with "ffmpeg" to make clear that
ffmpeg is printing these messages, and not us.
If libavcodec is from Libav, use "libav" as prefix instead. (In theory,
FFmpeg/Libav libraries could be mixed, but I don't think that is
actually possible in practice.)
libarclite provides method stubs for the Subscripting headers added in
0407869ae3. This allows to correclty build mpv on OSX 10.7 (I had tested that
commit with OSX 10.8 running 10.7 SDK).
It seems on 10.8 this option does't make any difference in the linked libraries
(checked with otool -L) so I just add it unconditionally.
Warning: This doesn't mean mpv moved to ARC. To do that one would have to add
`-fobjc-arc` to the cflags.
For quiet mode: ILDETECT_QUIET=1 ildetect.sh ...
Telecine decision (guess by ildetect.so) is verified by retrying the
ildetect run with the pullup filter inserted.
Recent work in the OS X parts of the code started using clang's support for
Obj-C's support for Literals and Subscripting. These particular language
features remove a lot of boilerplate code and allow to interact with
collections as consicely as one would do in scripting languages like Ruby or
Python.
Even if these are compiler features, Subscripting needs some runtime support.
This is provided with libarclite (coming with the compiler), but we need to
add the proper method definitions since the 10.7 SDK headers do not include
them. That is because 10.7 shipped before this language features.
This will cause some warnings when compiling with the 10.7 SDK because the
commit also redefines BOOL to make autoboxing/unboxing of BOOL literals to
work.
If you need to test this for whatever reason on 10.8, just pass in the correct
SDK to configure's extra cflags:
./configure --extra-cflags='-mmacosx-version-min=10.7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk'
Fixes#117
Or rather, keep hacking it until it somehow works. The problem here was
that trying to avoid calling STREAM_CTRL_GET_CURRENT_TIME too often
didn't really work, so the cache sometimes returned incorrect times.
Also try to avoid the situation that looking up the time with an
advanced read position doesn't really work, as well as when trying to
look it up when EOF or cache end has been reached. In that case we have
read_filepos == max_filepos, which is "outside" of the cache, but
querying the time is still valid.
Should also fix the issue that demuxing streams with demux_lavf and if
STREAM_CTRL_GET_CURRENT_TIME is not supported messed up the reported
playback position.
This stuff is still not sane, but the way the player tries to fix the
playback time and how the DVD/BD stream inputs return the current time
based on the current byte position isn't sane to begin with. So, let's
leave it at bad hacks.
The two changes that touch s->eof are unrelated and basically of
cosmetic nature (separate commit would be too noisy.)
Doing this makes the encoder force the same pict type as original, which
is often not even possible. Rather let the codec decide!
As there is no documented value to mean "decoder shall pick", I rather
save/restore the default value filled by libavcodec.
This is useless on the cache side. The sector is needed only to deal
with stream implementations which are not byte addressable, and the
cache is always byte addressable.
Also set a default read_chunk value. (This value is never used unless
you chain multiple caches, but it's cleaner.)
wm4
Stefano Pigozzi
Rudolf Polzer
Jonathan Yong