cras_unified.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
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 <cras_client.h>
14
15#include "base/compiler_specific.h"
16#include "media/audio/audio_io.h"
17#include "media/audio/audio_parameters.h"
18
19namespace media {
20
21class AudioManagerCras;
22
23// Implementation of AudioOuputStream for Chrome OS using the Chrome OS audio
24// server.
25class MEDIA_EXPORT CrasUnifiedStream : public AudioOutputStream {
26 public:
27  // The ctor takes all the usual parameters, plus |manager| which is the
28  // audio manager who is creating this object.
29  CrasUnifiedStream(const AudioParameters& params, AudioManagerCras* manager);
30
31  // The dtor is typically called by the AudioManager only and it is usually
32  // triggered by calling AudioUnifiedStream::Close().
33  virtual ~CrasUnifiedStream();
34
35  // Implementation of AudioOutputStream.
36  virtual bool Open() OVERRIDE;
37  virtual void Close() OVERRIDE;
38  virtual void Start(AudioSourceCallback* callback) OVERRIDE;
39  virtual void Stop() OVERRIDE;
40  virtual void SetVolume(double volume) OVERRIDE;
41  virtual void GetVolume(double* volume) OVERRIDE;
42
43 private:
44  // Convert Latency in time to bytes.
45  uint32 GetBytesLatency(const struct timespec& latency);
46
47  // Handles captured audio and fills the ouput with audio to be played.
48  static int UnifiedCallback(cras_client* client,
49                             cras_stream_id_t stream_id,
50                             uint8* input_samples,
51                             uint8* output_samples,
52                             unsigned int frames,
53                             const timespec* input_ts,
54                             const timespec* output_ts,
55                             void* arg);
56
57  // Handles notificaiton that there was an error with the playback stream.
58  static int StreamError(cras_client* client,
59                         cras_stream_id_t stream_id,
60                         int err,
61                         void* arg);
62
63  // Chooses the correct audio callback based on stream direction.
64  uint32 DispatchCallback(size_t frames,
65                          uint8* input_samples,
66                          uint8* output_samples,
67                          const timespec* input_ts,
68                          const timespec* output_ts);
69
70  // Receives input samples and write output samples for a unified I/O stream.
71  uint32 ReadWriteAudio(size_t frames,
72                        uint8* input_samples,
73                        uint8* output_samples,
74                        const timespec* input_ts,
75                        const timespec* output_ts);
76
77  // Writes audio for a playback stream.
78  uint32 WriteAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
79
80  // Deals with an error that occured in the stream.  Called from StreamError().
81  void NotifyStreamError(int err);
82
83  // The client used to communicate with the audio server.
84  cras_client* client_;
85
86  // ID of the playing stream.
87  cras_stream_id_t stream_id_;
88
89  // PCM parameters for the stream.
90  AudioParameters params_;
91
92  // Size of frame in bytes.
93  uint32 bytes_per_frame_;
94
95  // True if stream is playing.
96  bool is_playing_;
97
98  // Volume level from 0.0 to 1.0.
99  float volume_;
100
101  // Audio manager that created us.  Used to report that we've been closed.
102  AudioManagerCras* manager_;
103
104  // Callback to get audio samples.
105  AudioSourceCallback* source_callback_;
106
107  // Container for exchanging data with AudioSourceCallback::OnMoreIOData().
108  scoped_ptr<AudioBus> input_bus_;
109  scoped_ptr<AudioBus> output_bus_;
110
111  // Direciton of the stream.
112  CRAS_STREAM_DIRECTION stream_direction_;
113
114  DISALLOW_COPY_AND_ASSIGN(CrasUnifiedStream);
115};
116
117}  // namespace media
118
119#endif  // MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
120