Audio software mixer.

media/audio/audio_output_proxy.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 "media/audio/audio_output_proxy.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_output_dispatcher.h"
 
 AudioOutputProxy::AudioOutputProxy(AudioOutputDispatcher* dispatcher)
     : dispatcher_(dispatcher),
       state_(kCreated),
       physical_stream_(NULL),
-      volume_(1.0) {
+      volume_(1.0),
+      audio_source_callback_(NULL),
+      pending_bytes_(0) {
 }
 
 AudioOutputProxy::~AudioOutputProxy() {
   DCHECK(CalledOnValidThread());
   DCHECK(state_ == kCreated || state_ == kClosed);
   DCHECK(!physical_stream_);
+  DCHECK(!audio_source_callback_);
 }
 
 bool AudioOutputProxy::Open() {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(state_, kCreated);
 
   if (!dispatcher_->StreamOpened()) {
     state_ = kError;
     return false;
   }
 
   state_ = kOpened;
   return true;
 }
 
 void AudioOutputProxy::Start(AudioSourceCallback* callback) {
   DCHECK(CalledOnValidThread());
   DCHECK(physical_stream_ == NULL);
   DCHECK_EQ(state_, kOpened);

[tommi (sloooow) - chröme, 2012/04/03 13:47:51]

DCHECK(!audio_source_callback_)?

[enal1, 2012/04/04 18:46:55]

Done.

 
-  physical_stream_= dispatcher_->StreamStarted();
+  audio_source_callback_ = callback;

[tommi (sloooow) - chröme, 2012/04/03 13:47:51]

nit: just assign to this variable where you set state_ to kPlaying.

[enal1, 2012/04/04 18:46:55]

audio_source_callback_->OnMoreData() is called by dispatcher when starting the
stream.

+  pending_bytes_ = 0;
+  physical_stream_= dispatcher_->StreamStarted(callback, this);

[vrk (LEFT CHROMIUM), 2012/03/30 22:25:58]

Yikes, this is a big hack. If |dispatcher_| is an AudioOutputDispatcherImpl, you
return the physical stream, but if |dispatcher_| is an AudioOutputMixer, you
return the AudioOutputProxy, since the physical stream is kept in the
AudioOutputMixer instead of the proxy.

The physical stream(s) need to be kept in either the AudioOutputProxy *or*
derived classes of the dispatcher, but not both. I elaborate more feedback on
this in the overall comments.

[enal1, 2012/04/04 18:46:55]

Done.

   if (!physical_stream_) {
     state_ = kError;
     callback->OnError(this, 0);
+    audio_source_callback_ = NULL;
     return;
   }
 
-  physical_stream_->SetVolume(volume_);
-  physical_stream_->Start(callback);
   state_ = kPlaying;
 }
 
 void AudioOutputProxy::Stop() {
   DCHECK(CalledOnValidThread());
   if (state_ != kPlaying)
     return;
 
   DCHECK(physical_stream_);
-  physical_stream_->Stop();
-  dispatcher_->StreamStopped(physical_stream_);
+  dispatcher_->StreamStopped(physical_stream_, this);
   physical_stream_ = NULL;
+  audio_source_callback_ = NULL;
   state_ = kOpened;
 }
 
 void AudioOutputProxy::SetVolume(double volume) {
   DCHECK(CalledOnValidThread());
-  volume_ = volume;
-  if (physical_stream_) {
-    physical_stream_->SetVolume(volume);
+  {
+    base::AutoLock lock(lock_);
+    volume_ = volume;
   }
+  dispatcher_->StreamVolumeSet(physical_stream_, volume);
 }
 
 void AudioOutputProxy::GetVolume(double* volume) {
-  DCHECK(CalledOnValidThread());
+  base::AutoLock lock(lock_);
   *volume = volume_;
 }
 
 void AudioOutputProxy::Close() {
   DCHECK(CalledOnValidThread());
   DCHECK(state_ == kCreated || state_ == kError || state_ == kOpened);
   DCHECK(!physical_stream_);
+  DCHECK(!audio_source_callback_);
 
   if (state_ != kCreated)
-    dispatcher_->StreamClosed();
+    dispatcher_->StreamClosed(this);
 
   state_ = kClosed;
 
   // Delete the object now like is done in the Close() implementation of
   // physical stream objects.  If we delete the object via DeleteSoon, we
   // unnecessarily complicate the Shutdown procedure of the
   // dispatcher+audio manager.
   delete this;
 }