cras_input.h revision a36e5920737c6adbddd3e43b760e5de8431db6e0 
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 "base/memory/scoped_ptr.h"
14#include "base/memory/weak_ptr.h"
15#include "media/audio/agc_audio_stream.h"
16#include "media/audio/audio_io.h"
17#include "media/audio/audio_parameters.h"
18
19namespace media {
20
21class AudioManagerCras;
22
23// Provides an input stream for audio capture based on CRAS, the ChromeOS Audio
24// Server.  This object is not thread safe and all methods should be invoked in
25// the thread that created the object.
26class CrasInputStream : public AgcAudioStream<AudioInputStream> {
27 public:
28  // The ctor takes all the usual parameters, plus |manager| which is the
29  // audio manager who is creating this object.
30  CrasInputStream(const AudioParameters& params, AudioManagerCras* manager,
31                  const std::string& device_id);
32
33  // The dtor is typically called by the AudioManager only and it is usually
34  // triggered by calling AudioOutputStream::Close().
35  virtual ~CrasInputStream();
36
37  // Implementation of AudioInputStream.
38  virtual bool Open() OVERRIDE;
39  virtual void Start(AudioInputCallback* callback) OVERRIDE;
40  virtual void Stop() OVERRIDE;
41  virtual void Close() OVERRIDE;
42  virtual double GetMaxVolume() OVERRIDE;
43  virtual void SetVolume(double volume) OVERRIDE;
44  virtual double GetVolume() OVERRIDE;
45
46 private:
47  // Handles requests to get samples from the provided buffer.  This will be
48  // called by the audio server when it has samples ready.
49  static int SamplesReady(cras_client* client,
50                          cras_stream_id_t stream_id,
51                          uint8* samples,
52                          size_t frames,
53                          const timespec* sample_ts,
54                          void* arg);
55
56  // Handles notificaiton that there was an error with the playback stream.
57  static int StreamError(cras_client* client,
58                         cras_stream_id_t stream_id,
59                         int err,
60                         void* arg);
61
62  // Reads one or more buffers of audio from the device, passes on to the
63  // registered callback. Called from SamplesReady().
64  void ReadAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
65
66  // Deals with an error that occured in the stream.  Called from StreamError().
67  void NotifyStreamError(int err);
68
69  // Convert from dB * 100 to a volume ratio.
70  double GetVolumeRatioFromDecibels(double dB) const;
71
72  // Convert from a volume ratio to dB.
73  double GetDecibelsFromVolumeRatio(double volume_ratio) const;
74
75  // Non-refcounted pointer back to the audio manager.
76  // The AudioManager indirectly holds on to stream objects, so we don't
77  // want circular references.  Additionally, stream objects live on the audio
78  // thread, which is owned by the audio manager and we don't want to addref
79  // the manager from that thread.
80  AudioManagerCras* const audio_manager_;
81
82  // Size of frame in bytes.
83  uint32 bytes_per_frame_;
84
85  // Callback to pass audio samples too, valid while recording.
86  AudioInputCallback* callback_;
87
88  // The client used to communicate with the audio server.
89  cras_client* client_;
90
91  // PCM parameters for the stream.
92  const AudioParameters params_;
93
94  // True if the stream has been started.
95  bool started_;
96
97  // ID of the playing stream.
98  cras_stream_id_t stream_id_;
99
100  // Direction of the stream.
101  const CRAS_STREAM_DIRECTION stream_direction_;
102
103  DISALLOW_COPY_AND_ASSIGN(CrasInputStream);
104};
105
106}  // namespace media
107
108#endif  // MEDIA_AUDIO_CRAS_ALSA_INPUT_H_
109