media/audio/cras/cras_input.h

   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
  17 namespace media {
  18
  19 class 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.
  24 class 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_