Change the way we are sending audio data to driver when using WaveOut API.

media/audio/win/waveout_output_win.h

 // 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.
 
 #ifndef MEDIA_AUDIO_WIN_WAVEOUT_OUTPUT_WIN_H_
 #define MEDIA_AUDIO_WIN_WAVEOUT_OUTPUT_WIN_H_
 #pragma once
 
 #include <windows.h>
 #include <mmsystem.h>
 #include <mmreg.h>
 
 #include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "base/win/scoped_handle.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
 class AudioManagerWin;
 
 // Implements PCM audio output support for Windows using the WaveXXX API.
 // While not as nice as the DirectSound-based API, it should work in all target
 // operating systems regardless or DirectX version installed. It is known that
 // in some machines WaveXXX based audio is better while in others DirectSound
 // is better.
 //
 // Important: the OnXXXX functions in AudioSourceCallback are called by more
 // than one thread so it is important to have some form of synchronization if
 // you are keeping state in it.
 class PCMWaveOutAudioOutputStream : public AudioOutputStream {
+  friend class PlayingObject;
+
  public:
   // The ctor takes all the usual parameters, plus |manager| which is the
-  // the audio manager who is creating this object and |device_id| which
-  // is provided by the operating system.
+  // the audio manager who is creating this object and on which message loop
+  // "feeder" callbacks are running, and |device_id| which is provided by the
+  // operating system.
   PCMWaveOutAudioOutputStream(AudioManagerWin* manager,
                               const AudioParameters& params,
                               int num_buffers,
                               UINT device_id);
   virtual ~PCMWaveOutAudioOutputStream();
 
   // Implementation of AudioOutputStream.
   virtual bool Open();
   virtual void Close();
   virtual void Start(AudioSourceCallback* callback);
   virtual void Stop();
   virtual void SetVolume(double volume);
   virtual void GetVolume(double* volume);
 
   // Sends a buffer to the audio driver for playback.
   void QueueNextPacket(WAVEHDR* buffer);
 
  private:
   enum State {
     PCMA_BRAND_NEW,    // Initial state.
     PCMA_READY,        // Device obtained and ready to play.
     PCMA_PLAYING,      // Playing audio.
     PCMA_CLOSED        // Device has been released.
   };
 
-  // Windows calls us back to feed more data to the device here. See msdn
-  // documentation for 'waveOutProc' for details about the parameters.
+  // Internal reference-counted class used to speed up stopping of audio stream.
+  // By creating that separate object and passing it as argument we can stop
+  // playing immediately, not waiting till all scheduled callbacks finish.
+  // It is reference-counted, so it would be eventualy deleted.
+  class PlayingObject :
+      public base::RefCountedThreadSafe<PlayingObject> {
+   public:
+    // Accessors.
+    base::Lock* lock() {
+      return &lock_;
+    }
+    bool playing() const {
+      return stream_ != NULL;

[tommi (sloooow) - chröme, 2011/11/19 17:23:27]

should we lock lock_ here and in stop_playing() or DCHECK that the lock is
already held?

+    }
+    void stop_playing() {
+      stream_ = NULL;
+    }
+
+    PlayingObject(PCMWaveOutAudioOutputStream *stream);

[tommi (sloooow) - chröme, 2011/11/19 17:23:27]

PCMWaveOutAudioOutputStream* stream

+    ~PlayingObject();
+    // Feed the buffer to waveOut.
+    // Called on the audio manager thread.
+    void FeedBuffer(WAVEHDR* buffer, HWAVEOUT hwo);
+
+   private:
+    // Lock used to avoid the conflict between filling audio buffers and
+    // stopping the stream.
+    base::Lock lock_;
+    // Pointer to the parent object. Not owned.
+    PCMWaveOutAudioOutputStream *stream_;

[tommi (sloooow) - chröme, 2011/11/19 17:23:27]

PCMWaveOutAudioOutputStream* stream_;

+  };
+
+  // Returns pointer to the n-th buffer.
+  inline WAVEHDR* GetBuffer(int n) const;
+
+  // Size of one buffer in bytes, rounded up if necessary.
+  inline size_t BufferSize() const;
+
+  // Windows calls us back to free the buffer. See msdn documentation for
+  // 'waveOutProc' for details about the parameters.
   static void CALLBACK WaveCallback(HWAVEOUT hwo, UINT msg, DWORD_PTR instance,
                                     DWORD_PTR param1, DWORD_PTR param2);
 
   // If windows reports an error this function handles it and passes it to
   // the attached AudioSourceCallback::OnError().
   void HandleError(MMRESULT error);
-  // Allocates and prepares the memory that will be used for playback. Only
-  // two buffers are created.
+
+  // Allocates and prepares the memory that will be used for playback.
   void SetupBuffers();
+
   // Deallocates the memory allocated in SetupBuffers.
   void FreeBuffers();
 
   // Reader beware. Visual C has stronger guarantees on volatile vars than
   // most people expect. In fact, it has release semantics on write and
   // acquire semantics on reads. See the msdn documentation.
   volatile State state_;
 
   // The audio manager that created this output stream. We notify it when
   // we close so it can release its own resources.
@@ skipping 20 matching lines @@
   // The id assigned by the operating system to the selected wave output
   // hardware device. Usually this is just -1 which means 'default device'.
   UINT device_id_;
 
   // Windows native structure to encode the format parameters.
   WAVEFORMATPCMEX format_;
 
   // Handle to the instance of the wave device.
   HWAVEOUT waveout_;
 
-  // Pointer to the first allocated audio buffer. This object owns it.
-  WAVEHDR* buffer_;
+  // Pointer to the allocated audio buffers, we allocate all buffers in one big
+  // chunk. This object owns them.
+  scoped_array<char> buffers_;
 
-  // Lock used to prevent stopping the hardware callback thread while it is
-  // pending for data or feeding it to audio driver, because doing that causes
-  // the deadlock. Main thread gets that lock before stopping the playback.
-  // Callback tries to acquire that lock before entering critical code. If
-  // acquire fails then main thread is stopping the playback, callback should
-  // immediately return.
-  // Use Windows-specific lock, not Chrome one, because there is limited set of
-  // functions callback can use.
-  CRITICAL_SECTION lock_;
+  // Infamous aux object.

[tommi (sloooow) - chröme, 2011/11/19 17:23:27]

hah!

+  scoped_refptr<PlayingObject> playing_object_;
 
   DISALLOW_COPY_AND_ASSIGN(PCMWaveOutAudioOutputStream);
 };
 
 #endif  // MEDIA_AUDIO_WIN_WAVEOUT_OUTPUT_WIN_H_