Attempt to workaround junk channel and channel layout values.

Bug reports show a lot of users with junk dwChannelMask values,
yet working audio in other applications.  They also note that
this issue appeared recently; likely when we reverted support
for pass-through layouts to fix http://crbug.com/259165.

This fix enables guessing of channel layouts based on the
reported channel count and, if that's still bad, re-enables
support for pass-through layouts.

BUG=169846,309823,311906
TEST=none
R=scherkus@chromium.org

Review URL: https://codereview.chromium.org/54363009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232538 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 15 insertions, 1 deletions

diff --git a/media/audio/win/audio_manager_win.cc b/media/audio/win/audio_manager_win.cc
index 254fe36..06f9ccb 100644
--- a/media/audio/win/audio_manager_win.cc
+++ b/media/audio/win/audio_manager_win.cc
@@ -455,8 +455,12 @@ AudioParameters AudioManagerWin::GetPreferredOutputStreamParameters(
   }
 
   if (input_params.IsValid()) {
+    // If the user has enabled checking supported channel layouts or we don't
+    // have a valid channel layout yet, try to use the input layout.  See bugs
+    // http://crbug.com/259165 and http://crbug.com/311906 for more details.
     if (core_audio_supported &&
-        cmd_line->HasSwitch(switches::kTrySupportedChannelLayouts)) {
+        (cmd_line->HasSwitch(switches::kTrySupportedChannelLayouts) ||
+         channel_layout == CHANNEL_LAYOUT_UNSUPPORTED)) {
       // Check if it is possible to open up at the specified input channel
       // layout but avoid checking if the specified layout is the same as the
       // hardware (preferred) layout. We do this extra check to avoid the
diff --git a/media/audio/win/core_audio_util_win.cc b/media/audio/win/core_audio_util_win.cc
index 4771460..790b2b1 100644
--- a/media/audio/win/core_audio_util_win.cc
+++ b/media/audio/win/core_audio_util_win.cc
@@ -623,6 +623,16 @@ HRESULT CoreAudioUtil::GetPreferredAudioParameters(
   // Convert Microsoft's channel configuration to genric ChannelLayout.
   ChannelLayout channel_layout = ChannelConfigToChannelLayout(channel_config);
 
+  // Some devices don't appear to set a valid channel layout, so guess based on
+  // the number of channels.  See http://crbug.com/311906.
+  if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED) {
+    VLOG(1) << "Unsupported channel config: "
+            << std::hex << channel_config
+            << ".  Guessing layout by channel count: "
+            << std::dec << mix_format.Format.nChannels;
+    channel_layout = GuessChannelLayout(mix_format.Format.nChannels);
+  }
+
   // Preferred sample rate.
   int sample_rate = mix_format.Format.nSamplesPerSec;