remoting/host/linux/audio_pipe_reader.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 REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
   6 #define REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
   7
   8 #include "base/files/file.h"
   9 #include "base/files/file_path.h"
  10 #include "base/files/file_path_watcher.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "base/memory/ref_counted_memory.h"
  13 #include "base/message_loop/message_loop.h"
  14 #include "base/observer_list_threadsafe.h"
  15 #include "base/time/time.h"
  16 #include "base/timer/timer.h"
  17 #include "remoting/proto/audio.pb.h"
  18
  19 namespace remoting {
  20
  21 struct AudioPipeReaderTraits;
  22
  23 // AudioPipeReader class reads from a named pipe to which an audio server (e.g.
  24 // pulseaudio) writes the sound that's being played back and then sends data to
  25 // all registered observers.
  26 class AudioPipeReader
  27     : public base::RefCountedThreadSafe<AudioPipeReader, AudioPipeReaderTraits>,
  28       public base::MessageLoopForIO::Watcher {
  29  public:
  30   // PulseAudio's module-pipe-sink must be configured to use the following
  31   // parameters for the sink we read from.
  32   static const AudioPacket_SamplingRate kSamplingRate =
  33       AudioPacket::SAMPLING_RATE_48000;
  34   static const AudioPacket_BytesPerSample kBytesPerSample =
  35       AudioPacket::BYTES_PER_SAMPLE_2;
  36   static const AudioPacket_Channels kChannels = AudioPacket::CHANNELS_STEREO;
  37
  38   class StreamObserver {
  39    public:
  40     virtual void OnDataRead(scoped_refptr<base::RefCountedString> data) = 0;
  41   };
  42
  43   // |task_runner| specifies the IO thread to use to read data from the pipe.
  44   static scoped_refptr<AudioPipeReader> Create(
  45       scoped_refptr<base::SingleThreadTaskRunner> task_runner,
  46       const base::FilePath& pipe_path);
  47
  48   // Register or unregister an observer. Each observer receives data on the
  49   // thread on which it was registered and guaranteed not to be called after
  50   // RemoveObserver().
  51   void AddObserver(StreamObserver* observer);
  52   void RemoveObserver(StreamObserver* observer);
  53
  54   // MessageLoopForIO::Watcher interface.
  55   virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
  56   virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
  57
  58  private:
  59   friend class base::DeleteHelper<AudioPipeReader>;
  60   friend class base::RefCountedThreadSafe<AudioPipeReader>;
  61   friend struct AudioPipeReaderTraits;
  62
  63   AudioPipeReader(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
  64                   const base::FilePath& pipe_path);
  65   virtual ~AudioPipeReader();
  66
  67   void StartOnAudioThread();
  68   void OnDirectoryChanged(const base::FilePath& path, bool error);
  69   void TryOpenPipe();
  70   void StartTimer();
  71   void DoCapture();
  72   void WaitForPipeReadable();
  73
  74   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
  75   base::FilePath pipe_path_;
  76
  77   // Watcher for the directory that contains audio pipe we are reading from, to
  78   // monitor when pulseaudio creates or deletes it.
  79   base::FilePathWatcher file_watcher_;
  80
  81   base::File pipe_;
  82   base::RepeatingTimer<AudioPipeReader> timer_;
  83   scoped_refptr<ObserverListThreadSafe<StreamObserver> > observers_;
  84
  85   // Time when capturing was started.
  86   base::TimeTicks started_time_;
  87
  88   // Stream position of the last capture in bytes with zero position
  89   // corresponding to |started_time_|. Must always be a multiple of the sample
  90   // size.
  91   int64 last_capture_position_;
  92
  93   // Bytes left from the previous read.
  94   std::string left_over_bytes_;
  95
  96   base::MessageLoopForIO::FileDescriptorWatcher file_descriptor_watcher_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(AudioPipeReader);
  99 };
 100
 101 // Destroys |audio_pipe_reader| on the audio thread.
 102 struct AudioPipeReaderTraits {
 103   static void Destruct(const AudioPipeReader* audio_pipe_reader);
 104 };
 105
 106 }  // namespace remoting
 107
 108 #endif  // REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_