Same issue as 17a0f948.

This is required to make certain math defines visible on modern Cygwin.

This makes naming more consistent and simplifies extralibs-related changes.

This is more in line with the other related variable names.

These components should depend on the availability of the respective
libraries, not just on the availability of the respective headers.

These are taken care of more correctly by the library checks.

That header should only be included in the special bits that use X11 code.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Make avio_size() work with any write AVIOContext.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

Also preserve the return value from ff_get_buffer().
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

They are not valid and can cause problems/crashes for API users.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

Also use av_mallocz_array().

Bug-Id: CID 1396839
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Bug-Id: CID 1396851
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

The Solaris and Windows emulations of atomic_compare_exchange_strong()
need typecasts to avoid compiler warnings, because the functions they
call expect a void* pointer but an intptr_t integer is passed.

Note that the emulations of atomic_compare_exchange_strong() (except
the gcc version) only work for atomic_intptr_t because of the type of
the second argument (|expected|). See
http://en.cppreference.com/w/c/atomic:

_Bool atomic_compare_exchange_strong( volatile A* obj,
                                      C* expected, C desired );

The types of the first argument and second argument are different
(|A| and |C|, respectively). |C| is the non-atomic type corresponding
to |A|. In the emulations of atomic_compare_exchange_strong(), |C| is
intptr_t. This implies |A| can only be sig_intptr_t.
Signed-off-by: Wan-Teh Chang <wtc@google.com>

Make the one-time initialization in av_get_cpu_flags() thread-safe. The
static variables |flags|, |cpuflags_mask|, and |checked| in
libavutil/cpu.c are read and written using normal load and store
operations. These are considered as data races. The fix is to use atomic
load and store operations.

Remove the |checked| variable because the invalid value of -1 for
|flags| can be used to indicate the same condition. Rename |flags| to
|cpu_flags| and move it to file scope.

The fix can be verified by running the libavutil/tests/cpu_init.c test
program under ThreadSanitizer:
    ./configure --toolchain=clang-tsan
    make libavutil/tests/cpu_init
    libavutil/tests/cpu_init

There should be no warnings from ThreadSanitizer.

Co-author: Dmitry Vyukov of Google, who suggested the data race fix.
Signed-off-by: Wan-Teh Chang <wtc@google.com>

This fixes compilation after the next version bump.

This is the standard behavior for external libraries.

This allows expressing dependencies in a more correct way.

This implements Spherical Video V1 and V2, as described in the
spatial-media collection by Google.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

While no decoder currently exports spherical information, this type
represents a frame property that has to be passed through from container
to frames.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Fill it with AVStereo3D and AVDisplayMatrix documentation.
Apply the necessary changes to make verbatim code look good in doxygen.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

Otherwise builds without explicit target result in silent no-ops.

This makes sense and takes care of missing build dependencies.

The library versions are stored in the config.mak file and are used
to derive shared library names.

-pie was added to C flags for ThreadSanitizer in commit
19f251a2. Under clang 3.8.0, the -pie
flag causes a compiler warning and a linker error when running configure
--toolchain=clang-tsan. Here is an excerpt from config.log:

clang ... -fsanitize=thread -pie -std=c11 -fomit-frame-pointer -pthread -c -o /tmp/ffconf.A8SsaoCF.o /tmp/ffconf.JdpujQlD.c
clang: warning: argument unused during compilation: '-pie'
clang -fsanitize=thread -pie -Wl,--as-needed -o /tmp/ffconf.2iYA4bsw /tmp/ffconf.A8SsaoCF.o -lm -lm -lbz2 -lz -pthread
/usr/bin/ld: /tmp/ffconf.A8SsaoCF.o: relocation R_X86_64_PC32 against undefined symbol `atan2f@@GLIBC_2.2.5' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
clang: error: linker command failed with exit code 1 (use -v to see invocation)

To be conservative, I changed -pie to -fPIE. But the documentation seems
to imply just -fsanitize=thread is enough:

http://clang.llvm.org/docs/ThreadSanitizer.html
https://github.com/google/sanitizers/wiki/ThreadSanitizerCppManualSigned-off-by: Wan-Teh Chang <wtc@google.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

The generic parameter names used for CFLAGS in configure must be filtered
for each compiler and replaced by the equivalent flag for that compiler.