media/audio/cras/cras_unified.h

   1 // Copyright 2013 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 // Creates a unified stream based on the cras (ChromeOS audio server) interface.
   6 //
   7 // CrasUnifiedStream object is *not* thread-safe and should only be used
   8 // from the audio thread.
   9
  10 #ifndef MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
  11 #define MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_
  12
  13 #include <cras_client.h>
  14
  15 #include "base/compiler_specific.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 // Implementation of AudioOuputStream for Chrome OS using the Chrome OS audio
  24 // server.
  25 class MEDIA_EXPORT CrasUnifiedStream : public AudioOutputStream {
  26  public:
  27   // The ctor takes all the usual parameters, plus |manager| which is the
  28   // audio manager who is creating this object.
  29   CrasUnifiedStream(const AudioParameters& params, AudioManagerCras* manager);
  30
  31   // The dtor is typically called by the AudioManager only and it is usually
  32   // triggered by calling AudioUnifiedStream::Close().
  33   virtual ~CrasUnifiedStream();
  34
  35   // Implementation of AudioOutputStream.
  36   virtual bool Open() OVERRIDE;
  37   virtual void Close() OVERRIDE;
  38   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
  39   virtual void Stop() OVERRIDE;
  40   virtual void SetVolume(double volume) OVERRIDE;
  41   virtual void GetVolume(double* volume) OVERRIDE;
  42
  43  private:
  44   // Convert Latency in time to bytes.
  45   uint32 GetBytesLatency(const struct timespec& latency);
  46
  47   // Handles captured audio and fills the ouput with audio to be played.
  48   static int UnifiedCallback(cras_client* client,
  49                              cras_stream_id_t stream_id,
  50                              uint8* input_samples,
  51                              uint8* output_samples,
  52                              unsigned int frames,
  53                              const timespec* input_ts,
  54                              const timespec* output_ts,
  55                              void* arg);
  56
  57   // Handles notificaiton that there was an error with the playback stream.
  58   static int StreamError(cras_client* client,
  59                          cras_stream_id_t stream_id,
  60                          int err,
  61                          void* arg);
  62
  63   // Chooses the correct audio callback based on stream direction.
  64   uint32 DispatchCallback(size_t frames,
  65                           uint8* input_samples,
  66                           uint8* output_samples,
  67                           const timespec* input_ts,
  68                           const timespec* output_ts);
  69
  70   // Receives input samples and write output samples for a unified I/O stream.
  71   uint32 ReadWriteAudio(size_t frames,
  72                         uint8* input_samples,
  73                         uint8* output_samples,
  74                         const timespec* input_ts,
  75                         const timespec* output_ts);
  76
  77   // Writes audio for a playback stream.
  78   uint32 WriteAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
  79
  80   // Deals with an error that occured in the stream.  Called from StreamError().
  81   void NotifyStreamError(int err);
  82
  83   // The client used to communicate with the audio server.
  84   cras_client* client_;
  85
  86   // ID of the playing stream.
  87   cras_stream_id_t stream_id_;
  88
  89   // PCM parameters for the stream.
  90   AudioParameters params_;
  91
  92   // Size of frame in bytes.
  93   uint32 bytes_per_frame_;
  94
  95   // True if stream is playing.
  96   bool is_playing_;
  97
  98   // Volume level from 0.0 to 1.0.
  99   float volume_;
 100
 101   // Audio manager that created us.  Used to report that we've been closed.
 102   AudioManagerCras* manager_;
 103
 104   // Callback to get audio samples.
 105   AudioSourceCallback* source_callback_;
 106
 107   // Container for exchanging data with AudioSourceCallback::OnMoreIOData().
 108   scoped_ptr<AudioBus> input_bus_;
 109   scoped_ptr<AudioBus> output_bus_;
 110
 111   // Direciton of the stream.
 112   CRAS_STREAM_DIRECTION stream_direction_;
 113
 114   DISALLOW_COPY_AND_ASSIGN(CrasUnifiedStream);
 115 };
 116
 117 }  // namespace media
 118
 119 #endif  // MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_