FFmpeg recently split version.h into version.h and
version_major.h, and no longer automatically includes
version.h in avcodec.h (and the other libraries). This
should allow mpv to build against ffmpeg git master. See
FFmpeg/ffmpeg@f2da2e1458
These headers are not new, so their inclusion should not affect
backwards compatibility.
Libav seems rather dead: no release for 2 years, no new git commits in
master for almost a year (with one exception ~6 months ago). From what I
can tell, some developers resigned themselves to the horrifying idea to
post patches to ffmpeg-devel instead, while the rest of the developers
went on to greener pastures.
Libav was a better project than FFmpeg. Unfortunately, FFmpeg won,
because it managed to keep the name and website. Libav was pushed more
and more into obscurity: while there was initially a big push for Libav,
FFmpeg just remained "in place" and visible for most people. FFmpeg was
slowly draining all manpower and energy from Libav. A big part of this
was that FFmpeg stole code from Libav (regular merges of the entire
Libav git tree), making it some sort of Frankenstein mirror of Libav,
think decaying zombie with additional legs ("features") nailed to it.
"Stealing" surely is the wrong word; I'm just aping the language that
some of the FFmpeg members used to use. All that is in the past now, I'm
probably the only person left who is annoyed by this, and with this
commit I'm putting this decade long problem finally to an end. I just
thought I'd express my annoyance about this fucking shitshow one last
time.
The most intrusive change in this commit is the resample filter, which
originally used libavresample. Since the FFmpeg developer refused to
enable libavresample by default for drama reasons, and the API was
slightly different, so the filter used some big preprocessor mess to
make it compatible to libswresample. All that falls away now. The
simplification to the build system is also significant.
mpv warned if the FFmpeg runtime library version was not exactly the
same as the build version. This seemed to cause frequent conflicts. At
this point, most mpv code probably adheres to the FFmpeg ABI rules, and
FFmpeg stopped breaking ABI "accidentally". Another source of problems
were mixed FFmpeg/Libav installations, something which nobody does
anymore. It's not "our" job to check and enforce ABI compatibility
either. So I guess this behavior can be removed.
OK, still check for incompatible libraries (according to FFmpeg
versioning rules), i.e. different major versions, or if the build
version is newer than the runtime version. For now.
The comment about ABI problems is still true. In particular, the
bytes_read field mentioned in the removed comment is still accessed, and
is still an ABI violation. Have fun.
This includes codec/muxer/demuxer iteration (different iteration
function, registration functions deprecated), and the renaming of
AVFormatContext.filename to url (plus making it a malloced string).
Libav doesn't have the new API yet, so it will break. I hope they will
add the new APIs too.
I've decided that MP_TRACE means “noisy spam per frame”, whereas
MP_DBG just means “more verbose debugging messages than MSGL_V”.
Basically, MSGL_DBG shouldn't create spam per frame like it currently
does, and MSGL_V should make sense to the end-user and provide mostly
additional informational output.
MP_DBG is basically what I want to make the new default for --log-file,
so the cut-off point for MP_DBG is if we probably want to know if for
debugging purposes but the user most likely doesn't care about on the
terminal.
Also, the debug callbacks for libass and ffmpeg got bumped in their
verbosity levels slightly, because being external components they're a
bit less relevant to mpv debugging, and a bit too over-eager in what
they consider to be relevant information.
I exclusively used the "try it on my machine and remove messages from
MSGL_* until it does what I want it to" approach of refactoring, so
YMMV.
Apparently some people want this. Actually making it compile is still
their problem, though, and I expect that build with FFmpeg upstream will
occasionally be broken (as it is right now). This is because mpv also
relies on API provided by Libav, and if FFmpeg hasn't merged that yet,
it's not our problem - we provide a version of FFmpeg upstream with
those changes merged, and it's called ffmpeg-mpv.
Also adjust the README which still talked about FFmpeg releases.
See "Copyright" file for caveats.
This changes the remaining "almost LGPL" files to LGPL, because we think
that the conditions the author set for these was finally fulfilled.
In a first pass, we check whether libavcodec is present.
Then we try to compile a snippet and check for FFmpeg vs. Libav. (This
could probably also be done by somehow checking the pkgconfig version.
But pkg-config can't deal with that idiotic FFmpeg idea that a micro
version number >= 100 identifies FFmpeg vs. Libav.)
After that we check the project-specific version numbers. This means it
can no longer happen that we accidentally allow older, unsupported
versions of FFmpeg, just because the Libav version numbers are somehow
this way.
Also drop the resampler checks. We hardcode which resampler to each with
each project. A user can no longer force use of libavresample with
FFmpeg.
We don't support this anymore.
This tries to exit in a controlled way after command line options are
applied in order to honor logging options and, in case of libmpv, not to
kill the host. Not sure if it would be better to just vomit text to
stderr and call abort().
We want to add a prefix to the ffmpeg log message, so we called mp_msg
multiple times until now. But logging such partial lines is a race
condition, because there's only one internal mp_msg buffer, and no
external mp_msg locks.
Avoid this by building the message on a stack buffer.
I might make a mp_log-local partial line buffer, but even then av_log()
can be called from multiple threads, while targetting the same mp_log.
(Really, ffmpeg's log API needs to be fixed.)
The complex filter support that will be added makes much more complex
use of libavfilter, and I'm not going to bother with adding hacks to
keep libavfilter optional.
This happens with av_log(NULL, ...) calls. Drop the "?: " fallback
prefix, because it was confusing.
(Of course FFmpeg should not do this at all, but it's a very long way to
making the FFmpeg log callback sane.)
This is slightly "dangerous", because it could overwrite a log callback
another library has set, after we've set our own callback. But it's
probably still slightly better than leaving our own callback, which will
run the fallback code if no mpv instance is set. (Multiple mpv instances
sharing the same global state will safely avoid overwriting each other's
log callback.)
Note that we can't do much better, because the global state in FFmpeg is
obviously insane.
The code in main.c calls exit() explicitly, but the code is actually
easier to follow by simply exiting from main() instead. The exit() call
in av_log.c happens only on severely broken builds, so replace it with
abort().
(Shuts up rpmlint warnings.)
Print a warning if a library has mismatched compile time and link time
versions.
Refuse to work if the compile time and link time versions are a mix of
ffmpeg and libav. We print an error message and call exit(). Since we'd
randomly crash anyway, I think this is ok.
This doesn't catch the case if you e.g. use a ffmpeg libavcodec and a
libav libavformat, which would of course just crash as quickly, but I
think this checks enough already.
This is pretty nasty, because FFmpeg/Libav is yet another library with a
global message callback. We do something with mutexes trying to get it
done, but of course we can't actually solve this problem. If more than
one library in a process use FFmpeg/Libav, only one of them will get log
messages.
Always pass around mp_log contexts in the option parser code. This of
course affects all users of this API as well.
In stream.c, pass a mp_null_log, because we can't do it properly yet.
This will be fixed later.
Kacper Michajłow
Jan Ekström
Leo Izen
wm4
Niklas Haas
Marcin Kurczewski