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 // TODO(dgreid): This class is used for only output, either remove all the
  26 // relevant input code and change the class to CrasOutputStream or merge
  27 // cras_input.cc into this unified implementation.
  28 class MEDIA_EXPORT CrasUnifiedStream : public AudioOutputStream {
  29  public:
  30   // The ctor takes all the usual parameters, plus |manager| which is the
  31   // audio manager who is creating this object.
  32   CrasUnifiedStream(const AudioParameters& params, AudioManagerCras* manager);
  33
  34   // The dtor is typically called by the AudioManager only and it is usually
  35   // triggered by calling AudioUnifiedStream::Close().
  36   ~CrasUnifiedStream() override;
  37
  38   // Implementation of AudioOutputStream.
  39   bool Open() override;
  40   void Close() override;
  41   void Start(AudioSourceCallback* callback) override;
  42   void Stop() override;
  43   void SetVolume(double volume) override;
  44   void GetVolume(double* volume) override;
  45
  46  private:
  47   // Convert Latency in time to bytes.
  48   uint32 GetBytesLatency(const struct timespec& latency);
  49
  50   // Handles captured audio and fills the ouput with audio to be played.
  51   static int UnifiedCallback(cras_client* client,
  52                              cras_stream_id_t stream_id,
  53                              uint8* input_samples,
  54                              uint8* output_samples,
  55                              unsigned int frames,
  56                              const timespec* input_ts,
  57                              const timespec* output_ts,
  58                              void* arg);
  59
  60   // Handles notification that there was an error with the playback stream.
  61   static int StreamError(cras_client* client,
  62                          cras_stream_id_t stream_id,
  63                          int err,
  64                          void* arg);
  65
  66   // Chooses the correct audio callback based on stream direction.
  67   uint32 DispatchCallback(size_t frames,
  68                           uint8* input_samples,
  69                           uint8* output_samples,
  70                           const timespec* input_ts,
  71                           const timespec* output_ts);
  72
  73   // Writes audio for a playback stream.
  74   uint32 WriteAudio(size_t frames, uint8* buffer, const timespec* sample_ts);
  75
  76   // Deals with an error that occured in the stream.  Called from StreamError().
  77   void NotifyStreamError(int err);
  78
  79   // The client used to communicate with the audio server.
  80   cras_client* client_;
  81
  82   // ID of the playing stream.
  83   cras_stream_id_t stream_id_;
  84
  85   // PCM parameters for the stream.
  86   AudioParameters params_;
  87
  88   // Size of frame in bytes.
  89   uint32 bytes_per_frame_;
  90
  91   // True if stream is playing.
  92   bool is_playing_;
  93
  94   // Volume level from 0.0 to 1.0.
  95   float volume_;
  96
  97   // Audio manager that created us.  Used to report that we've been closed.
  98   AudioManagerCras* manager_;
  99
 100   // Callback to get audio samples.
 101   AudioSourceCallback* source_callback_;
 102
 103   // Container for exchanging data with AudioSourceCallback::OnMoreData().
 104   scoped_ptr<AudioBus> output_bus_;
 105
 106   // Direciton of the stream.
 107   CRAS_STREAM_DIRECTION stream_direction_;
 108
 109   DISALLOW_COPY_AND_ASSIGN(CrasUnifiedStream);
 110 };
 111
 112 }  // namespace media
 113
 114 #endif  // MEDIA_AUDIO_LINUX_CRAS_UNIFIED_H_