Adds support for 16kHz input sample rate and mono channel config. in WebRTC.

media/audio/audio_util.cc

 // 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.
 
 // Software adjust volume of samples, allows each audio stream its own
 // volume without impacting master volume for chrome and other applications.
 
 // Implemented as templates to allow 8, 16 and 32 bit implementations.
 // 8 bit is unsigned and biased by 128.
 
@@ skipping 319 matching lines @@
     return 480;
   else if (mixing_sample_rate == 44100)
     return 448;
   else
     return 960;
 #else
   return 2048;
 #endif
 }
 
+uint32 GetAudioInputHardwareChannelCount() {
+  enum channel_layout { MONO = 1, STEREO = 2 };
+#if defined(OS_MACOSX)
+  return MONO;
+#elif defined(OS_WIN)
+  if (!IsWASAPISupported()) {
+    // Fall back to Windows Wave implementation on Windows XP or lower and
+    // use stereo by default.
+    return STEREO;
+  }
+  return WASAPIAudioInputStream::HardwareChannelCount(eConsole);
+#else
+  return STEREO;
+#endif
+}
+
 // When transferring data in the shared memory, first word is size of data
 // in bytes. Actual data starts immediately after it.
 
 uint32 TotalSharedMemorySizeInBytes(uint32 packet_size) {
   // Need to reserve extra 4 bytes for size of data.
   return packet_size + sizeof(Atomic32);
 }
 
 uint32 PacketSizeSizeInBytes(uint32 shared_memory_created_size) {
   return shared_memory_created_size - sizeof(Atomic32);
@@ skipping 64 matching lines @@
     case 1:
       DoCrossfade(bytes_to_crossfade, number_of_channels, bytes_per_channel,
                   src, dest);
       break;
     default:
       NOTREACHED() << "Unsupported audio bit depth in crossfade.";
   }
 }
 
 }  // namespace media