cras_input.h revision 90dce4d38c5ff5333bea97d859d4e484e27edf0c 
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
32  // The dtor is typically called by the AudioManager only and it is usually
33  // triggered by calling AudioOutputStream::Close().
34  virtual ~CrasInputStream();
35
36  // Implementation of AudioInputStream.
37  virtual bool Open() OVERRIDE;
38  virtual void Start(AudioInputCallback* callback) OVERRIDE;
39  virtual void Stop() OVERRIDE;
40  virtual void Close() OVERRIDE;
41  virtual double GetMaxVolume() OVERRIDE;
42  virtual void SetVolume(double volume) OVERRIDE;
43  virtual double GetVolume() OVERRIDE;
44
45 private:
46  // Handles requests to get samples from the provided buffer.  This will be
47  // called by the audio server when it has samples ready.
48  static int SamplesReady(cras_client* client,
49                          cras_stream_id_t stream_id,
50                          uint8* samples,
51                          size_t frames,
52                          const timespec* sample_ts,
53                          void* arg);
54
55  // Handles notificaiton that there was an error with the playback stream.
56  static int StreamError(cras_client* client,
57                         cras_stream_id_t stream_id,
58                         int err,
59                         void* arg);
60
61  // Reads one or more buffers of audio from the device, passes on to the
62  // registered callback. Called from SamplesReady().
63  void ReadAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
64
65  // Deals with an error that occured in the stream.  Called from StreamError().
66  void NotifyStreamError(int err);
67
68  // Convert from dB * 100 to a volume ratio.
69  double GetVolumeRatioFromDecibels(double dB) const;
70
71  // Convert from a volume ratio to dB.
72  double GetDecibelsFromVolumeRatio(double volume_ratio) const;
73
74  // Non-refcounted pointer back to the audio manager.
75  // The AudioManager indirectly holds on to stream objects, so we don't
76  // want circular references.  Additionally, stream objects live on the audio
77  // thread, which is owned by the audio manager and we don't want to addref
78  // the manager from that thread.
79  AudioManagerCras* audio_manager_;
80
81  // Size of frame in bytes.
82  uint32 bytes_per_frame_;
83
84  // Callback to pass audio samples too, valid while recording.
85  AudioInputCallback* callback_;
86
87  // The client used to communicate with the audio server.
88  cras_client* client_;
89
90  // PCM parameters for the stream.
91  AudioParameters params_;
92
93  // True if the stream has been started.
94  bool started_;
95
96  // ID of the playing stream.
97  cras_stream_id_t stream_id_;
98
99  DISALLOW_COPY_AND_ASSIGN(CrasInputStream);
100};
101
102}  // namespace media
103
104#endif  // MEDIA_AUDIO_CRAS_ALSA_INPUT_H_
105