Linux: make it possible to compile against libav when use_system_ffmpeg==1

media/media.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'chromium_code': 1,
     # Override to dynamically link the cras (ChromeOS audio) library.
     'use_cras%': 0,
     # Option e.g. for Linux distributions to link pulseaudio directly
@@ skipping 490 matching lines @@
               'MEDIA_DISABLE_LIBVPX',
             ],
           },
           # Exclude the sources that depend on libvpx.
           'sources!': [
             'filters/vpx_video_decoder.cc',
             'filters/vpx_video_decoder.h',
           ],
         }],
         ['use_system_ffmpeg == 1', {
-          'defines': [
+          'cflags': [

[DaleCurtis, 2013/04/15 23:12:53]

This section is pretty different than the previous. I don't understand your
changes here. Has compile_test changed in some way?

[Paweł Hajdan Jr., 2013/04/15 23:51:49]

defines -> cflags avoids a problem with gyp appending empty -D switches (may be
a change in gyp, may be a result of my test with more recent libraries)

__STDC_CONSTANT_MACROS is to avoid a spurious failure that happens when using
C++ compiler and makes the compile test always fail.

[DaleCurtis, 2013/04/16 20:46:56]

Can you put the #define and #include in a variable?

[Paweł Hajdan Jr., 2013/04/16 20:59:36]

I could technically, but unless you insist I'd prefer the current way.

The tests are supposed to be independent - any similarities between them are
accidental.

It is arguably easier to reason about them when you can see the whole program.

Otherwise - why not de-duplicate int main() { } in the same way? But IMO it
would actually decrease readability for no gain.

             '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
-                '--code "#include <libavcodec/avcodec.h>\n'
+                '--code "#define __STDC_CONSTANT_MACROS\n'
+                '#include <libavcodec/avcodec.h>\n'
                 'int test() { return AV_CODEC_ID_OPUS; }" '
-                '--on-failure CHROMIUM_OMIT_AV_CODEC_ID_OPUS)',
+                '--on-failure -DCHROMIUM_OMIT_AV_CODEC_ID_OPUS=1)',
+
             '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
-                '--code "#include <libavcodec/avcodec.h>\n'
+                '--code "#define __STDC_CONSTANT_MACROS\n'
+                '#include <libavcodec/avcodec.h>\n'
                 'int test() { return AV_CODEC_ID_VP9; }" '
-                '--on-failure CHROMIUM_OMIT_AV_CODEC_ID_VP9)',
+                '--on-failure -DCHROMIUM_OMIT_AV_CODEC_ID_VP9=1)',
+
+            '<!(python <(DEPTH)/tools/compile_test/compile_test.py '
+                '--code "#define __STDC_CONSTANT_MACROS\n'
+                '#include <libavcodec/avcodec.h>\n'
+                'int test() { struct AVFrame frame;\n'
+                'return av_frame_get_channels(&frame); }" '
+                '--on-failure '
+                '"\'-Dav_frame_get_channels(frame)=(av_get_channel_layout_nb_channels('
+                'frame->channel_layout))\'")',
           ],
         }],
         ['OS == "ios"', {
           'includes': [
             # For shared_memory_support_sources variable.
             'shared_memory_support.gypi',
           ],
           'sources': [
             'base/media_stub.cc',
             # These sources are normally built via a dependency on the
@@ skipping 1159 matching lines @@
           ],
           'sources': [
             'base/simd/sinc_resampler_sse.cc',
             'base/simd/vector_math_sse.cc',
           ],
         }, # end of target media_sse
       ],
     }],
   ],
 }