pulse_output.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4//
5// Creates an audio output stream based on the PulseAudio asynchronous API;
6// specifically using the pa_threaded_mainloop model.
7//
8// If the stream is successfully opened, Close() must be called before the
9// stream is deleted as Close() is responsible for ensuring resource cleanup
10// occurs.
11//
12// This object is designed so that all AudioOutputStream methods will be called
13// on the same thread that created the object.
14//
15// WARNING: This object blocks on internal PulseAudio calls in Open() while
16// waiting for PulseAudio's context structure to be ready.  It also blocks in
17// inside PulseAudio in Start() and repeated during playback, waiting for
18// PulseAudio write callbacks to occur.
19
20#ifndef MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
21#define MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
22
23#include <string>
24
25#include "base/memory/scoped_ptr.h"
26#include "media/audio/audio_io.h"
27#include "media/audio/audio_parameters.h"
28
29struct pa_context;
30struct pa_operation;
31struct pa_stream;
32struct pa_threaded_mainloop;
33
34namespace media {
35class AudioManagerBase;
36
37class PulseAudioOutputStream : public AudioOutputStream {
38 public:
39  PulseAudioOutputStream(const AudioParameters& params,
40                         const std::string& device_id,
41                         AudioManagerBase* manager);
42
43  virtual ~PulseAudioOutputStream();
44
45  // Implementation of AudioOutputStream.
46  virtual bool Open() OVERRIDE;
47  virtual void Close() OVERRIDE;
48  virtual void Start(AudioSourceCallback* callback) OVERRIDE;
49  virtual void Stop() OVERRIDE;
50  virtual void SetVolume(double volume) OVERRIDE;
51  virtual void GetVolume(double* volume) OVERRIDE;
52
53 private:
54  // Called by PulseAudio when |pa_stream_| change state.  If an unexpected
55  // failure state change happens and |source_callback_| is set
56  // this method will forward the error via OnError().
57  static void StreamNotifyCallback(pa_stream* s, void* p_this);
58
59  // Called by PulseAudio when it needs more audio data.
60  static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this);
61
62  // Fulfill a write request from the write request callback.  Outputs silence
63  // if the request could not be fulfilled.
64  void FulfillWriteRequest(size_t requested_bytes);
65
66  // Close() helper function to free internal structs.
67  void Reset();
68
69  // AudioParameters from the constructor.
70  const AudioParameters params_;
71
72  // The device ID for the device to open.
73  const std::string device_id_;
74
75  // Audio manager that created us.  Used to report that we've closed.
76  AudioManagerBase* manager_;
77
78  // PulseAudio API structs.
79  pa_context* pa_context_;
80  pa_threaded_mainloop* pa_mainloop_;
81  pa_stream* pa_stream_;
82
83  // Float representation of volume from 0.0 to 1.0.
84  float volume_;
85
86  // Callback to audio data source.  Must only be modified while holding a lock
87  // on |pa_mainloop_| via pa_threaded_mainloop_lock().
88  AudioSourceCallback* source_callback_;
89
90  // Container for retrieving data from AudioSourceCallback::OnMoreData().
91  scoped_ptr<AudioBus> audio_bus_;
92
93  DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
94};
95
96}  // namespace media
97
98#endif  // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
99