Low-latency AudioOutputStream implementation based on WASAPI for Windows.

media/audio/win/audio_manager_win.cc

 // Copyright (c) 2011 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/audio_io.h"
 
 #include <windows.h>
 #include <objbase.h>  // This has to be before initguid.h
 #include <initguid.h>
 #include <mmsystem.h>
 #include <setupapi.h>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/win/windows_version.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/audio/fake_audio_output_stream.h"
 #include "media/audio/win/audio_low_latency_input_win.h"
+#include "media/audio/win/audio_low_latency_output_win.h"
 #include "media/audio/win/audio_manager_win.h"
 #include "media/audio/win/wavein_input_win.h"
 #include "media/audio/win/waveout_output_win.h"
 #include "media/base/limits.h"
 
 // Libraries required for the SetupAPI and Wbem APIs used here.
 #pragma comment(lib, "setupapi.lib")
 
 // The following are defined in various DDK headers, and we (re)define them
 // here to avoid adding the DDK as a chrome dependency.
@@ skipping 71 matching lines @@
 bool AudioManagerWin::HasAudioOutputDevices() {
   return (::waveOutGetNumDevs() != 0);
 }
 
 bool AudioManagerWin::HasAudioInputDevices() {
   return (::waveInGetNumDevs() != 0);
 }
 
 // Factory for the implementations of AudioOutputStream. Two implementations
 // should suffice most windows user's needs.
-// - PCMWaveOutAudioOutputStream: Based on the waveOutWrite API (in progress)
-// - PCMDXSoundAudioOutputStream: Based on DirectSound or XAudio (future work).
+// - PCMWaveOutAudioOutputStream: Based on the waveOut API.
+// - WASAPIAudioOutputStream: Based on Core Audio (WASAPI) API.
 AudioOutputStream* AudioManagerWin::MakeAudioOutputStream(
     const AudioParameters& params) {
   if (!params.IsValid() || (params.channels > kWinMaxChannels))
     return NULL;
 
   // Limit the number of audio streams opened.
   if (num_output_streams_ >= kMaxOutputStreams) {
     return NULL;
   }
 
   if (params.format == AudioParameters::AUDIO_MOCK) {
     return FakeAudioOutputStream::MakeFakeStream(params);
   } else if (params.format == AudioParameters::AUDIO_PCM_LINEAR) {
     num_output_streams_++;
     return new PCMWaveOutAudioOutputStream(this, params, 3, WAVE_MAPPER);
   } else if (params.format == AudioParameters::AUDIO_PCM_LOW_LATENCY) {
     num_output_streams_++;
-    // TODO(cpu): waveout cannot hit 20ms latency. Use other method.
-    return new PCMWaveOutAudioOutputStream(this, params, 2, WAVE_MAPPER);
+    if (base::win::GetVersion() <= base::win::VERSION_XP) {
+      // Fall back to Windows Wave implementation on Windows XP or lower.
+      DLOG(INFO) << "Using WaveOut since WASAPI requires at least Vista.";
+      return new PCMWaveOutAudioOutputStream(this, params, 2, WAVE_MAPPER);
+    } else {
+      // TODO(henrika): improve possibility to specify audio endpoint.
+      // Use the default device (same as for Wave) for now to be compatible.
+      return new WASAPIAudioOutputStream(this, params, eConsole);
+    }
   }
   return NULL;
 }
 
 // Factory for the implementations of AudioInputStream.
 AudioInputStream* AudioManagerWin::MakeAudioInputStream(
     const AudioParameters& params) {
   if (!params.IsValid() || (params.channels > kWinMaxInputChannels))
     return NULL;
 
@@ skipping 10 matching lines @@
                                            WAVE_MAPPER);
     } else {
       // TODO(henrika): improve possibility to specify audio endpoint.
       // Use the default device (same as for Wave) for now to be compatible.
       return new WASAPIAudioInputStream(this, params, eConsole);
     }
   }
   return NULL;
 }
 
-void AudioManagerWin::ReleaseOutputStream(PCMWaveOutAudioOutputStream* stream) {
+void AudioManagerWin::ReleaseOutputStream(AudioOutputStream* stream) {
   DCHECK(stream);
   num_output_streams_--;
   delete stream;
 }
 
 void AudioManagerWin::ReleaseInputStream(AudioInputStream* stream) {
   delete stream;
 }
 
 void AudioManagerWin::MuteAll() {
@@ skipping 98 matching lines @@
     name.device_name = AudioManagerBase::kDefaultDeviceName;
     name.unique_id = "0";
     device_names->push_back(name);
   }
 }
 
 // static
 AudioManager* AudioManager::CreateAudioManager() {
   return new AudioManagerWin();
 }