cras_input.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#ifndef MEDIA_AUDIO_CRAS_CRAS_INPUT_H_
6#define MEDIA_AUDIO_CRAS_CRAS_INPUT_H_
7
8#include <cras_client.h>
9
10#include <string>
11
12#include "base/compiler_specific.h"
13#include "media/audio/agc_audio_stream.h"
14#include "media/audio/audio_io.h"
15#include "media/audio/audio_parameters.h"
16
17namespace media {
18
19class AudioManagerCras;
20
21// Provides an input stream for audio capture based on CRAS, the ChromeOS Audio
22// Server.  This object is not thread safe and all methods should be invoked in
23// the thread that created the object.
24class CrasInputStream : public AgcAudioStream<AudioInputStream> {
25 public:
26  // The ctor takes all the usual parameters, plus |manager| which is the
27  // audio manager who is creating this object.
28  CrasInputStream(const AudioParameters& params, AudioManagerCras* manager,
29                  const std::string& device_id);
30
31  // The dtor is typically called by the AudioManager only and it is usually
32  // triggered by calling AudioOutputStream::Close().
33  virtual ~CrasInputStream();
34
35  // Implementation of AudioInputStream.
36  virtual bool Open() OVERRIDE;
37  virtual void Start(AudioInputCallback* callback) OVERRIDE;
38  virtual void Stop() OVERRIDE;
39  virtual void Close() OVERRIDE;
40  virtual double GetMaxVolume() OVERRIDE;
41  virtual void SetVolume(double volume) OVERRIDE;
42  virtual double GetVolume() OVERRIDE;
43
44 private:
45  // Handles requests to get samples from the provided buffer.  This will be
46  // called by the audio server when it has samples ready.
47  static int SamplesReady(cras_client* client,
48                          cras_stream_id_t stream_id,
49                          uint8* samples,
50                          size_t frames,
51                          const timespec* sample_ts,
52                          void* arg);
53
54  // Handles notificaiton that there was an error with the playback stream.
55  static int StreamError(cras_client* client,
56                         cras_stream_id_t stream_id,
57                         int err,
58                         void* arg);
59
60  // Reads one or more buffers of audio from the device, passes on to the
61  // registered callback. Called from SamplesReady().
62  void ReadAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
63
64  // Deals with an error that occured in the stream.  Called from StreamError().
65  void NotifyStreamError(int err);
66
67  // Convert from dB * 100 to a volume ratio.
68  double GetVolumeRatioFromDecibels(double dB) const;
69
70  // Convert from a volume ratio to dB.
71  double GetDecibelsFromVolumeRatio(double volume_ratio) const;
72
73  // Non-refcounted pointer back to the audio manager.
74  // The AudioManager indirectly holds on to stream objects, so we don't
75  // want circular references.  Additionally, stream objects live on the audio
76  // thread, which is owned by the audio manager and we don't want to addref
77  // the manager from that thread.
78  AudioManagerCras* const audio_manager_;
79
80  // Size of frame in bytes.
81  uint32 bytes_per_frame_;
82
83  // Callback to pass audio samples too, valid while recording.
84  AudioInputCallback* callback_;
85
86  // The client used to communicate with the audio server.
87  cras_client* client_;
88
89  // PCM parameters for the stream.
90  const AudioParameters params_;
91
92  // True if the stream has been started.
93  bool started_;
94
95  // ID of the playing stream.
96  cras_stream_id_t stream_id_;
97
98  // Direction of the stream.
99  const CRAS_STREAM_DIRECTION stream_direction_;
100
101  DISALLOW_COPY_AND_ASSIGN(CrasInputStream);
102};
103
104}  // namespace media
105
106#endif  // MEDIA_AUDIO_CRAS_CRAS_INPUT_H_
107