Introduce AudioOutputResampler for browser side resampling.

content/renderer/pepper/pepper_platform_audio_output_impl.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.
 
 #include "content/renderer/pepper/pepper_platform_audio_output_impl.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/message_loop_proxy.h"
 #include "build/build_config.h"
 #include "content/common/child_process.h"
 #include "content/common/media/audio_messages.h"
 #include "content/renderer/media/audio_hardware.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/render_thread_impl.h"
+#include "media/base/media_switches.h"
 
 namespace content {
 
 // static
 PepperPlatformAudioOutputImpl* PepperPlatformAudioOutputImpl::Create(
     int sample_rate,
     int frames_per_buffer,
     webkit::ppapi::PluginDelegate::PlatformAudioOutputClient* client) {
   scoped_refptr<PepperPlatformAudioOutputImpl> audio_output(
       new PepperPlatformAudioOutputImpl());
@@ skipping 88 matching lines @@
     int frames_per_buffer,
     webkit::ppapi::PluginDelegate::PlatformAudioOutputClient* client) {
   DCHECK(client);
   // Make sure we don't call init more than once.
   DCHECK_EQ(0, stream_id_);
 
   client_ = client;
 
   media::AudioParameters::Format format;
   const int kMaxFramesForLowLatency = 2047;
-  // Use the low latency back end if the client request is compatible, and
-  // the sample count is low enough to justify using AUDIO_PCM_LOW_LATENCY.
-  if (sample_rate == audio_hardware::GetOutputSampleRate() &&
-      frames_per_buffer <= kMaxFramesForLowLatency &&
-      frames_per_buffer % audio_hardware::GetOutputBufferSize() == 0) {
+
+  const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  if (cmd_line->HasSwitch(switches::kEnableAudioOutputResampler)) {
+    // Rely on AudioOutputResampler to handle any inconsistencies between the
+    // hardware params required for low latency and the requested params.
+    format = media::AudioParameters::AUDIO_PCM_LOW_LATENCY;
+  } else if (sample_rate == audio_hardware::GetOutputSampleRate() &&
+             frames_per_buffer <= kMaxFramesForLowLatency &&
+             frames_per_buffer % audio_hardware::GetOutputBufferSize() == 0) {
+    // Use the low latency back end if the client request is compatible, and
+    // the sample count is low enough to justify using AUDIO_PCM_LOW_LATENCY.
     format = media::AudioParameters::AUDIO_PCM_LOW_LATENCY;
   } else {
     format = media::AudioParameters::AUDIO_PCM_LINEAR;
   }
 
   media::AudioParameters params(format, CHANNEL_LAYOUT_STEREO, sample_rate, 16,
                                 frames_per_buffer);
 
   ChildProcess::current()->io_message_loop()->PostTask(
       FROM_HERE,
@@ skipping 25 matching lines @@
 
   ipc_->CloseStream(stream_id_);
   ipc_->RemoveDelegate(stream_id_);
   stream_id_ = 0;
 
   Release();  // Release for the delegate, balances out the reference taken in
               // PepperPluginDelegateImpl::CreateAudio.
 }
 
 }  // namespace content