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,
  29                   AudioManagerCras* manager,
  30                   const std::string& device_id);
  31
  32   // The dtor is typically called by the AudioManager only and it is usually
  33   // triggered by calling AudioOutputStream::Close().
  34   ~CrasInputStream() override;
  35
  36   // Implementation of AudioInputStream.
  37   bool Open() override;
  38   void Start(AudioInputCallback* callback) override;
  39   void Stop() override;
  40   void Close() override;
  41   double GetMaxVolume() override;
  42   void SetVolume(double volume) override;
  43   double GetVolume() override;
  44   bool IsMuted() 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 notification 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   scoped_ptr<AudioBus> audio_bus_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(CrasInputStream);
 106 };
 107
 108 }  // namespace media
 109
 110 #endif  // MEDIA_AUDIO_CRAS_CRAS_INPUT_H_