cras_unified.h revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d 
1// Copyright 2013 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 a unified stream based on the cras (ChromeOS audio server) interface.
6//
7// CrasUnifiedStream object is *not* thread-safe and should only be used
8// from the audio thread.
9
10#ifndef MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
11#define MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
12
13#include <alsa/asoundlib.h>
14#include <cras_client.h>
15
16#include "base/compiler_specific.h"
17#include "base/gtest_prod_util.h"
18#include "media/audio/audio_io.h"
19#include "media/audio/audio_parameters.h"
20
21namespace media {
22
23class AudioManagerCras;
24class AudioParameters;
25
26// Implementation of AudioOuputStream for Chrome OS using the Chrome OS audio
27// server.
28class MEDIA_EXPORT CrasUnifiedStream : public AudioOutputStream {
29 public:
30  // The ctor takes all the usual parameters, plus |manager| which is the
31  // audio manager who is creating this object.
32  CrasUnifiedStream(const AudioParameters& params, AudioManagerCras* manager);
33
34  // The dtor is typically called by the AudioManager only and it is usually
35  // triggered by calling AudioUnifiedStream::Close().
36  virtual ~CrasUnifiedStream();
37
38  // Implementation of AudioOutputStream.
39  virtual bool Open() OVERRIDE;
40  virtual void Close() OVERRIDE;
41  virtual void Start(AudioSourceCallback* callback) OVERRIDE;
42  virtual void Stop() OVERRIDE;
43  virtual void SetVolume(double volume) OVERRIDE;
44  virtual void GetVolume(double* volume) OVERRIDE;
45
46 private:
47  // Convert Latency in time to bytes.
48  uint32 GetBytesLatency(const struct timespec& latency);
49
50  // Handles captured audio and fills the ouput with audio to be played.
51  static int UnifiedCallback(cras_client* client,
52                             cras_stream_id_t stream_id,
53                             uint8* input_samples,
54                             uint8* output_samples,
55                             unsigned int frames,
56                             const timespec* input_ts,
57                             const timespec* output_ts,
58                             void* arg);
59
60  // Handles notificaiton that there was an error with the playback stream.
61  static int StreamError(cras_client* client,
62                         cras_stream_id_t stream_id,
63                         int err,
64                         void* arg);
65
66  // Chooses the correct audio callback based on stream direction.
67  uint32 DispatchCallback(size_t frames,
68                          uint8* input_samples,
69                          uint8* output_samples,
70                          const timespec* input_ts,
71                          const timespec* output_ts);
72
73  // Receives input samples and write output samples for a unified I/O stream.
74  uint32 ReadWriteAudio(size_t frames,
75                        uint8* input_samples,
76                        uint8* output_samples,
77                        const timespec* input_ts,
78                        const timespec* output_ts);
79
80  // Writes audio for a playback stream.
81  uint32 WriteAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
82
83  // Deals with an error that occured in the stream.  Called from StreamError().
84  void NotifyStreamError(int err);
85
86  // The client used to communicate with the audio server.
87  cras_client* client_;
88
89  // ID of the playing stream.
90  cras_stream_id_t stream_id_;
91
92  // PCM parameters for the stream.
93  AudioParameters params_;
94
95  // Size of frame in bytes.
96  uint32 bytes_per_frame_;
97
98  // True if stream is playing.
99  bool is_playing_;
100
101  // Volume level from 0.0 to 1.0.
102  float volume_;
103
104  // Audio manager that created us.  Used to report that we've been closed.
105  AudioManagerCras* manager_;
106
107  // Callback to get audio samples.
108  AudioSourceCallback* source_callback_;
109
110  // Container for exchanging data with AudioSourceCallback::OnMoreIOData().
111  scoped_ptr<AudioBus> input_bus_;
112  scoped_ptr<AudioBus> output_bus_;
113
114  // Direciton of the stream.
115  CRAS_STREAM_DIRECTION stream_direction_;
116
117  DISALLOW_COPY_AND_ASSIGN(CrasUnifiedStream);
118};
119
120}  // namespace media
121
122#endif  // MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
123