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 "base/threading/thread_checker.h"
27#include "media/audio/audio_io.h"
28#include "media/audio/audio_parameters.h"
29
30struct pa_context;
31struct pa_operation;
32struct pa_stream;
33struct pa_threaded_mainloop;
34
35namespace media {
36class AudioManagerBase;
37
38class PulseAudioOutputStream : public AudioOutputStream {
39 public:
40  PulseAudioOutputStream(const AudioParameters& params,
41                         const std::string& device_id,
42                         AudioManagerBase* manager);
43
44  virtual ~PulseAudioOutputStream();
45
46  // Implementation of AudioOutputStream.
47  virtual bool Open() OVERRIDE;
48  virtual void Close() OVERRIDE;
49  virtual void Start(AudioSourceCallback* callback) OVERRIDE;
50  virtual void Stop() OVERRIDE;
51  virtual void SetVolume(double volume) OVERRIDE;
52  virtual void GetVolume(double* volume) OVERRIDE;
53
54 private:
55  // Called by PulseAudio when |pa_stream_| change state.  If an unexpected
56  // failure state change happens and |source_callback_| is set
57  // this method will forward the error via OnError().
58  static void StreamNotifyCallback(pa_stream* s, void* p_this);
59
60  // Called by PulseAudio when it needs more audio data.
61  static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this);
62
63  // Fulfill a write request from the write request callback.  Outputs silence
64  // if the request could not be fulfilled.
65  void FulfillWriteRequest(size_t requested_bytes);
66
67  // Close() helper function to free internal structs.
68  void Reset();
69
70  // AudioParameters from the constructor.
71  const AudioParameters params_;
72
73  // The device ID for the device to open.
74  const std::string device_id_;
75
76  // Audio manager that created us.  Used to report that we've closed.
77  AudioManagerBase* manager_;
78
79  // PulseAudio API structs.
80  pa_context* pa_context_;
81  pa_threaded_mainloop* pa_mainloop_;
82  pa_stream* pa_stream_;
83
84  // Float representation of volume from 0.0 to 1.0.
85  float volume_;
86
87  // Callback to audio data source.  Must only be modified while holding a lock
88  // on |pa_mainloop_| via pa_threaded_mainloop_lock().
89  AudioSourceCallback* source_callback_;
90
91  // Container for retrieving data from AudioSourceCallback::OnMoreData().
92  scoped_ptr<AudioBus> audio_bus_;
93
94  base::ThreadChecker thread_checker_;
95
96  DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
97};
98
99}  // namespace media
100
101#endif  // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
102