When targeting the "windows store application" (metro) API subset
(or the windows phone API subset), the getenv function isn't
available. If it is unavailable, just define getenv to NULL.

The check uses check_func_headers, since the function actually
might exist in the libraries, but is hidden in the headers.

The fallback is in config.h since msvc can't do -D defines with
parameters on the command line, and it's used both within the
libraries and the frontend applications (so a libavutil internal
header wouldn't be enough).
Signed-off-by: Martin Storsjö <martin@martin.st>

The functions which actually drive the filter graph by pushing
frames through it need to ensure an aligned stack for SIMD functions.

This fixes a crash in YADIF filter when using a mingw build in a MSVC
application.
Signed-off-by: Martin Storsjö <martin@martin.st>

This should fix misdetection of AVS files as AviSynth scripts
when AviSynth support is enabled (Bugzilla #357).

output-example links against swscale, which depends on avutil.  In standard
configurations, by pure good luck, the libs before swscale pull in all of
swscale's dependencies and linking succeeds.  However, in some configurations
like --disable-asm this is not the case and linking fails.

Hardcode the dependency to avoid a more general Makefile refactoring.

Signed-off-by: Diego Biurrun <diego@biurrun.de>

With the parameter --valgrind-memcheck, the configure script sets
reasonable defaults that can be overridden as explained in the
documentation.

The idea of using set_defaults is from Luca Barbato.

Without this, lcov sometimes misses to normalize paths that contain "/./".
Also, ignore uninteresting hits in system headers.

In the default settings, both tools produce a lot of unhelpful noise.

This patch can be controversial, by assuming floats are IEEE-754 and
particular behaviour of the FPU will get in the way.
Timing on Arrandale and Win32 (thus, x87 FPU is used in the reference).

sbr_qmf_pre_shuffle_c: 115 to 76
sbr_neg_odd_64_c: 84 to 55
sbr_qmf_post_shuffle_c: 112 to 83
Signed-off-by: Diego Biurrun <diego@biurrun.de>

1410 cycles to 1148 on Arrandale/Win64
Signed-off-by: Diego Biurrun <diego@biurrun.de>

Sandybridge: 47 cycles

Having a loop counter is a 7 cycle gain.
Unrolling is another 7 cycle gain.
Working in reverse scan is another 6 cycles.
Signed-off-by: Diego Biurrun <diego@biurrun.de>

If building libav with -MD in the cflags (for making the MSVC compiler
generate code for using a dynamically linked libc), the system headers
that declare strtod, snprintf and vsnprintf declare the functions as
imported from a DLL. To hook up wrappers of our own for these functions,
the function names are defined to avpriv_*, so that the calling code
within libav calls the wrappers instead. Since these functions
are declared to be imported from DLLs, the calling code expects to
load them from DLL import function pointers (creating references to
_imp__avpriv_strtod instead of directly to avpriv_strtod). If the
libav libraries are not built as DLLs, no such function pointers (as
the calling code expects) are created.

The linker can fix this up automatically in some cases (producing
warnings LNK4217 and LNK4049), if the object files are already
included. By telling the linker to try to include those symbols
(without the _imp prefix as the calling code ends up using),
we get the object files included, so that the linker can do the
automatic fixup. This is done via config.h, so that all (or at least
most) of the object files in our libraries force including the compat
files, to make sure they are included regardless of what files from our
static libraries actually are included.
Signed-off-by: Martin Storsjö <martin@martin.st>

Prevent a serious out of buffer bound write.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC:libav-stable@libav.org

Hack partially based on a commit by Michael Niedermayer <michaelni@gmx.at>
Should fix (or work around) bug 458.

Integrate the code in the packet reading function, instead of inserting
sleeps in many places.
This is simpler to follow and should work better.

Signed-off-by: Anton Khirnov <anton@khirnov.net>

Signed-off-by: Anton Khirnov <anton@khirnov.net>

Signed-off-by: Anton Khirnov <anton@khirnov.net>

97c -> 49c
Some codecs could benefit from more unrolling, but AAC doesn't.

-t 0.5 is 12.5 frames at 25 fps, which may round to either 12 or 13 on
different platforms.

It has been deprecated some time ago, but was forgotten during the last
bump.

This avoids cases where configure tries to weakly enable an item
which actually is disabled, ending up still enabling dependencies
of the item which itself is only enabled weakly.

More concretely, the h264 decoder suggests error resilience, which
is then enabled weakly (unless manually disabled). Previously,
dsputil, which is a dependency of error resilience, was enabled
even if error resilience wasn't enabled in the end.
Signed-off-by: Martin Storsjö <martin@martin.st>

The variable name 'var' is commonly used to iterate through arguments
in other functions. When the pushvar function internally uses the
variable 'var', it makes pushing/popping the variable 'var' not
work as intended.
Signed-off-by: Martin Storsjö <martin@martin.st>

Signed-off-by: Diego Biurrun <diego@biurrun.de>