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 "base/memory/scoped_ptr.h"
  14 #include "base/memory/weak_ptr.h"
  15 #include "media/audio/audio_input_stream_impl.h"
  16 #include "media/audio/audio_io.h"
  17 #include "media/audio/audio_parameters.h"
  18
  19 namespace media {
  20
  21 class 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.
  26 class CrasInputStream : public AudioInputStreamImpl {
  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_