PulseAudio Sound Playback on Linux

media/audio/linux/pulse_output.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_LINUX_PULSE_OUTPUT_H_
+#define MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_
+
+#include <pulse/pulseaudio.h>
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "media/audio/audio_io.h"
+#include "media/audio/audio_parameters.h"
+
+namespace media {
+class SeekableBuffer;
+}
+
+class AudioManagerLinux;
+
+class PulseAudioOutputStream : public AudioOutputStream {
+ public:
+  PulseAudioOutputStream(const AudioParameters& params,
+                         AudioManagerLinux* manager);
+
+  virtual ~PulseAudioOutputStream();
+
+  // 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);
+
+ private:
+  // PulseAudio Callbacks.
+  static void ContextStateCallback(pa_context* context, void* userdata);
+  static void WriteCallback(pa_stream* stream, size_t length, void* userdata);
+
+  // Functions to get another packet from the data source and write it into the
+  // PulseAudio device.
+  void ClientBufferLoop();
+  void BufferPacketInClient();
+
+  // API for Proxying calls to the AudioSourceCallback provided during Start().
+  uint32 RunDataCallback(uint8* dest,

[vrk (LEFT CHROMIUM), 2011/08/10 16:34:51]

Can these parameters fit on one line?

[slock, 2011/08/10 22:41:04]

Done.  Well two of them can anyway.

+                         uint32 max_size,
+                         AudioBuffersState buffers_state);
+
+  // Configuration constants from the constructor.  Referencable by all threads
+  // since they are constants.
+  const ChannelLayout channel_layout_;
+  const pa_sample_format_t sample_format_;
+  const uint32 sample_rate_;
+  const uint32 bytes_per_frame_;
+
+  // Device configuration data.  Populated after OpenTask() completes.
+  uint32 packet_size_;
+  uint32 frames_per_packet_;
+
+  // 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_;
+
+  // Audio manager that created us.  Used to report that we've closed.
+  AudioManagerLinux* manager_;
+
+  // PulseAudio API structs.
+  pa_mainloop* pa_mainloop_;
+  pa_mainloop_api* pa_mainloop_api_;
+  pa_context* pa_context_;
+
+  // PulseAudio attribute and specification structs.
+  pa_sample_spec pa_sample_specs_;
+  pa_buffer_attr pa_buffer_attributes_;
+  pa_cvolume pa_volume_;
+
+  // Handle to the actual PulseAudio playback stream.
+  pa_stream* playback_handle_;
+
+  // Internal buffer.
+  scoped_ptr<media::SeekableBuffer> client_buffer_;
+  bool source_exhausted_;
+
+  AudioSourceCallback* source_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
+};
+
+#endif  // MEDIA_AUDIO_LINUX_PULSE_OUTPUT_H_