Not all compilers on all platforms have atomics available (even if they
could, technically speaking).
We don't use atomics that much, only the following things rely on it:
1. the audio pull code, and all audio outputs using it
2. updating global msg levels
3. reading log messages through the client API
Just disable 1. and 3. if atomics are not available. For 2., using fake-
atomics isn't too bad; at worst, message levels won't properly update
under certain situations (but most likely, it will work just fine).
This means if atomics are not available, the client API function
mpv_request_log_messages() will do nothing.
CC: @mpv-player/stable
We don't need to combine __sync_add_and_fetch with a memory barrier,
since these intrinsics are documented as using a full barrier already.
Use __sync_fetch_and_add instead of __sync_add_and_fetch; this gives
atomic_fetch_add() the correct return value (although we don't use it).
Use __sync_fetch_and_add to emulate atomic_load(). This should enforce
the full barrier semantics better. (This trick is stolen from the
FreeBSD based stdatomic.h emulation.)
This should be more correct. The builtins were made to directly map to
C11, and the way we use them is now relatively close to how gcc
implements atomics in 4.9. In particular, we make use of the load and
store builtins.
I'm not entirely sure why gcc didn't support stdatomic.h in 4.8 already.
Maybe support for the builtins was incomplete or broken - so there's a
lot of room for doubt about the correctness of this.
In my opinion, we shouldn't use atomics at all, but ok.
This switches the mpv code to use C11 stdatomic.h, and for compilers
that don't support stdatomic.h yet, we emulate the subset used by mpv
using the builtins commonly provided by gcc and clang.
This supersedes an earlier similar attempt by Kovensky. That attempt
unfortunately relied on a big copypasted freebsd header (which also
depended on much more highly compiler-specific functionality, defined
reserved symbols, etc.), so it had to be NIH'ed.
Some issues:
- C11 says default initialization of atomics "produces a valid state",
but it's not sure whether the stored value is really 0. But we rely on
this.
- I'm pretty sure our use of the __atomic... builtins is/was incorrect.
We don't use atomic load/store intrinsics, and access stuff directly.
- Our wrapper actually does stricter typechecking than the stdatomic.h
implementation by gcc 4.9. We make the atomic types incompatible with
normal types by wrapping them into structs. (The FreeBSD wrapper does
the same.)
- I couldn't test on MinGW.
Currently, it's unused. Still keep the file, because it's not unlikely
we'll need it again, and removing/readding the include statements for
this file is too annoying.
Not needed anymore. I'm not opposed to having asm, but inline asm is too
much of a pain, and it was planned long ago to eventually get rid fo all
inline asm uses.
For the note, the inline asm use that was removed with the previous
commits was almost worthless. It was confined to video filters, and most
video filtering is now done with libavfilter. Some mpv filters (like
vf_pullup) actually redirect to libavfilter if possible.
If asm is added in the future, it should happen in the form of external
files.
Libav 9 still uses the unprefixed PIX_FMT_... symbols, but they will
probably be removed some time in the future.
There are some other deprecations we have yet to take care of, but
there are no clear replacements yet.
We consider FFmpeg 1.x and Libav 0.9.x releases compatible. Support
for FFmpeg 0.9.x and Libav 0.8.x is considered infeasible and has been
dropped in the previous commits. The bits that break compatibility are
mainly the CodecID renaming (trivial, but would require nasty hacks
everywhere), the avcodec_encode_video2() function (missing in older
releases, mandatory in newer ones), and the resampler changes (older
releases miss lib{av,sw}resample, newer versions removed the
libavcodec resampler).
Remove some other compatibility bits that were needed to for releases
for which we drop support.
The comment about Libav 0.9 in compat/libav.h is incorrect and should
have been 0.8 (the symbol is present in Libav 0.9).
The old names have been deprecated a while ago, but were needed for
supporting older ffmpeg/libav versions. The deprecated identifiers
have been removed from recent Libav and FFmpeg git.
This change breaks compatibility with Libav 0.8.x and equivalent
FFmpeg releases.
The EXTERN_PREFIX definition changed in 94b7db2 needs a separate case
for _WIN64, as MinGW defines both that and _WIN32 but there is no prefix
unlike 32-bit case.
Patch by redxii on http://devel.mplayer2.org/ticket/226
Doesn't define AVPROBE_SCORE_RETRY for some reason. They use
AVPROBE_SCORE_MAX/4 directly internally. AV_DISPOSITION_ATTACHED_PIC
is not defined with the most recent Libav release.
AVIOContext.av_class exists in Libav, but is apparently disabled in
old releases. Disable it for now until people stop torturing me with
old crap releases.
Libav 0.8.4 is ridiculously old (in relative terms), so I don't know
how many things are broken silently.
Encoding is disabled, because the required API hasn't been added yet.
(On the other hand, the old API can't be used in newer versions.)
This should improve compatibility with ffmpeg 0.11.2 as well, which
didn't define AV_CODEC_ID_SUBRIP yet.
Put MP_EXPAND_ARGS() in compiler.h, even though it's not compiler
dependent. Both mp_talloc.h and mp_common.h need it, while mp_common.h
includes mp_talloc.h. This is the least annoying solution.
Tis drops the silly lib prefixes, and attempts to organize the tree in
a more logical way. Make the top-level directory less cluttered as
well.
Renames the following directories:
libaf -> audio/filter
libao2 -> audio/out
libvo -> video/out
libmpdemux -> demux
Split libmpcodecs:
vf* -> video/filter
vd*, dec_video.* -> video/decode
mp_image*, img_format*, ... -> video/
ad*, dec_audio.* -> audio/decode
libaf/format.* is moved to audio/ - this is similar to how mp_image.*
is located in video/.
Move most top-level .c/.h files to core. (talloc.c/.h is left on top-
level, because it's external.) Park some of the more annoying files
in compat/. Some of these are relicts from the time mplayer used
ffmpeg internals.
sub/ is not split, because it's too much of a mess (subtitle code is
mixed with OSD display and rendering).
Maybe the organization of core is not ideal: it mixes playback core
(like mplayer.c) and utility helpers (like bstr.c/h). Should the need
arise, the playback core will be moved somewhere else, while core
contains all helper and common code.
