Move Alsa device opening into the audio thread, and add in support for multi-channel audio.

media/audio/linux/audio_manager_linux.cc

 // Copyright (c) 2006-2009 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.
 
 #include "media/audio/linux/audio_manager_linux.h"
 
 #include "base/at_exit.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "media/audio/fake_audio_output_stream.h"
 #include "media/audio/linux/alsa_output.h"
 #include "media/audio/linux/alsa_wrapper.h"
+#include "media/base/media_switches.h"
+
 
 namespace {
 AudioManagerLinux* g_audio_manager = NULL;
 }  // namespace
 
 // Implementation of AudioManager.
 bool AudioManagerLinux::HasAudioDevices() {
   // TODO(ajwong): Make this actually query audio devices.
   return true;
 }
 
 AudioOutputStream* AudioManagerLinux::MakeAudioStream(Format format,
                                                       int channels,
                                                       int sample_rate,
                                                       char bits_per_sample) {
   // Early return for testing hook.  Do this before checking for
   // |initialized_|.
   if (format == AudioManager::AUDIO_MOCK) {
     return FakeAudioOutputStream::MakeFakeStream();
   }
 
   if (!initialized_) {
     return NULL;
   }
 
-  // TODO(ajwong): Do we want to be able to configure the device? default
-  // should work correctly for all mono/stereo, but not surround, which needs
-  // surround40, surround51, etc.
-  //
-  // http://0pointer.de/blog/projects/guide-to-sound-apis.html
+  std::string device_name = AlsaPcmOutputStream::kAutoSelectDevice;
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kAlsaDevice)) {
+    device_name = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+        switches::kAlsaDevice);
+  }
   AlsaPcmOutputStream* stream =
-      new AlsaPcmOutputStream(AlsaPcmOutputStream::kDefaultDevice,
-                              format, channels, sample_rate, bits_per_sample,
-                              wrapper_.get(), this,
+      new AlsaPcmOutputStream(device_name, format, channels, sample_rate,
+                              bits_per_sample, wrapper_.get(), this,
                               audio_thread_.message_loop());
 
   AutoLock l(lock_);
   active_streams_[stream] = scoped_refptr<AlsaPcmOutputStream>(stream);
   return stream;
 }
 
 AudioManagerLinux::AudioManagerLinux()
     : audio_thread_("AudioThread"),
       initialized_(false) {
@@ skipping 28 matching lines @@
 }
 
 AudioManager* AudioManager::GetAudioManager() {
   if (!g_audio_manager) {
     g_audio_manager = new AudioManagerLinux();
     g_audio_manager->Init();
     base::AtExitManager::RegisterCallback(&DestroyAudioManagerLinux, NULL);
   }
   return g_audio_manager;
 }