Get PulseAudio implementation working.

media/audio/pulse/pulse_output.h

 // 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.
 //
 // Creates an audio output stream based on the PulseAudio asynchronous API.

[scherkus (not reviewing), 2012/10/10 17:56:29]

does this comment need to be updated?

[DaleCurtis, 2012/10/10 18:19:05]

It's still accurate, but I'll add some details on the pa_threaded_mainloop
stuff.

 //
 // If the stream is successfully opened, Close() must be called before the
 // stream is deleted as Close() is responsible for ensuring resource cleanup
 // occurs.
 //
 // This object is designed so that all AudioOutputStream methods will be called
 // on the same thread that created the object.
 //
 // WARNING: This object blocks on internal PulseAudio calls in Open() while
 // waiting for PulseAudio's context structure to be ready.  It also blocks in
 // inside PulseAudio in Start() and repeated during playback, waiting for
 // PulseAudio write callbacks to occur.
 
 #ifndef MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
 #define MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
 
 #include <pulse/pulseaudio.h>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
 #include "media/audio/audio_io.h"
-#include "media/base/channel_layout.h"
+#include "media/audio/audio_parameters.h"
 
 namespace media {
 
 #if defined(OS_LINUX)
 class AudioManagerLinux;
 typedef AudioManagerLinux AudioManagerPulse;
 #elif defined(OS_OPENBSD)
 class AudioManagerOpenBSD;
 typedef AudioManagerOpenBSD AudioManagerPulse;
 #else
 #error Unsupported platform
 #endif
 
-class AudioParameters;
-class SeekableBuffer;
-
 class PulseAudioOutputStream : public AudioOutputStream {
  public:
   PulseAudioOutputStream(const AudioParameters& params,
                          AudioManagerPulse* manager);
 
   virtual ~PulseAudioOutputStream();
 
   // Implementation of AudioOutputStream.
   virtual bool Open() OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void SetVolume(double volume) OVERRIDE;
   virtual void GetVolume(double* volume) OVERRIDE;
 
  private:
   // PulseAudio Callbacks.
-  static void ContextStateCallback(pa_context* context, void* state_addr);
+  static void ContextStateCallback(pa_context* context, void* p_this);
+  static void StreamStateCallback(pa_stream* stream, void* p_this);
   static void WriteRequestCallback(pa_stream* playback_handle, size_t length,
                                    void* stream_addr);
 
-  // Iterate the PulseAudio mainloop to get write requests.
-  void WaitForWriteRequest();
+  // Retrieve a packet of audio data from |source_callback_| and write it to
+  // |interleaved_audio_data_|.  Returns the number of frames written.
+  int FillBuffer();
 
-  // Get another packet from the data source and write it to the client buffer.
-  bool BufferPacketFromSource();
-
-  // Fulfill a write request from the write request callback.  If the write
-  // can't be finished a first, post a new attempt to the message loop.
+  // Fulfill a write request from the write request callback.  Outputs silence
+  // if the request could not be fulfilled.
   void FulfillWriteRequest(size_t requested_bytes);
 
-  // Write data from the client buffer to the PulseAudio stream.
-  void WriteToStream(size_t bytes_to_write, size_t* bytes_written);
-
   // API for Proxying calls to the AudioSourceCallback provided during Start().
   int RunDataCallback(AudioBus* audio_bus, AudioBuffersState buffers_state);
 
   // Close() helper function to free internal structs.
   void Reset();
 
-  // Configuration constants from the constructor.  Referencable by all threads
-  // since they are constants.
-  const ChannelLayout channel_layout_;
-  const uint32 channel_count_;
-  const pa_sample_format_t sample_format_;
-  const uint32 sample_rate_;
-  const uint32 bytes_per_frame_;
+  // AudioParameters from the constructor.
+  const AudioParameters params_;
 
   // Audio manager that created us.  Used to report that we've closed.
   AudioManagerPulse* manager_;
 
   // PulseAudio API structs.
   pa_context* pa_context_;
-  pa_mainloop* pa_mainloop_;
+  pa_threaded_mainloop* pa_mainloop_;
 
   // Handle to the actual PulseAudio playback stream.
   pa_stream* playback_handle_;
 
-  // Device configuration data.  Populated after Open() completes.
-  uint32 packet_size_;
-  uint32 frames_per_packet_;
-
-  // Client side audio buffer feeding pulse audio's server side buffer.
-  scoped_ptr<media::SeekableBuffer> client_buffer_;
-
   // Float representation of volume from 0.0 to 1.0.
   float volume_;
 
   // Flag indicating the code should stop reading from the data source or
   // writing to the PulseAudio server.  This is set because the device has
   // entered an unrecoverable error state, or the Close() has executed.
   bool stream_stopped_;
 
-  // Whether or not PulseAudio has called the WriteCallback for the most recent
-  // set of pa_mainloop iterations.
-  bool write_callback_handled_;
-
-  // Allows us to run tasks on the PulseAudioOutputStream instance which are
-  // bound by its lifetime.
-  base::WeakPtrFactory<PulseAudioOutputStream> weak_factory_;
-
   // Callback to audio data source.
   AudioSourceCallback* source_callback_;
 
   // Container for retrieving data from AudioSourceCallback::OnMoreData().
   scoped_ptr<AudioBus> audio_bus_;
+  scoped_array<uint8> interleaved_audio_data_;

[DaleCurtis, 2012/10/10 18:19:05]

Looks like I can remove this too by using pa_stream_begin_write() to get
pulseaudio to hand me a buffer!

+
+  volatile pa_stream_state_t stream_state_;
+  volatile pa_context_state_t context_state_;
 
   DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_