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      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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_
      6 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_
      7 
      8 #include "base/file_descriptor_posix.h"
      9 #include "base/process/process.h"
     10 #include "base/sync_socket.h"
     11 #include "base/synchronization/lock.h"
     12 #include "base/time/time.h"
     13 #include "media/audio/audio_output_controller.h"
     14 #include "media/base/audio_bus.h"
     15 
     16 namespace base {
     17 class SharedMemory;
     18 }
     19 
     20 namespace content {
     21 
     22 // A AudioOutputController::SyncReader implementation using SyncSocket. This
     23 // is used by AudioOutputController to provide a low latency data source for
     24 // transmitting audio packets between the browser process and the renderer
     25 // process.
     26 class AudioSyncReader : public media::AudioOutputController::SyncReader {
     27  public:
     28   AudioSyncReader(base::SharedMemory* shared_memory,
     29                   const media::AudioParameters& params,
     30                   int input_channels);
     31 
     32   virtual ~AudioSyncReader();
     33 
     34   // media::AudioOutputController::SyncReader implementations.
     35   virtual void UpdatePendingBytes(uint32 bytes) OVERRIDE;
     36   virtual int Read(bool block,
     37                    const media::AudioBus* source,
     38                    media::AudioBus* dest) OVERRIDE;
     39   virtual void Close() OVERRIDE;
     40 
     41   bool Init();
     42   bool PrepareForeignSocketHandle(base::ProcessHandle process_handle,
     43 #if defined(OS_WIN)
     44                                   base::SyncSocket::Handle* foreign_handle);
     45 #else
     46                                   base::FileDescriptor* foreign_handle);
     47 #endif
     48 
     49  private:
     50   // Indicates whether the renderer has data available for reading.
     51   bool DataReady();
     52 
     53   // Blocks until DataReady() is true or a timeout expires.
     54   void WaitTillDataReady();
     55 
     56   base::SharedMemory* shared_memory_;
     57 
     58   // Number of input channels for synchronized I/O.
     59   int input_channels_;
     60 
     61   // Mutes all incoming samples. This is used to prevent audible sound
     62   // during automated testing.
     63   bool mute_audio_;
     64 
     65   // Socket for transmitting audio data.
     66   scoped_ptr<base::CancelableSyncSocket> socket_;
     67 
     68   // Socket to be used by the renderer. The reference is released after
     69   // PrepareForeignSocketHandle() is called and ran successfully.
     70   scoped_ptr<base::CancelableSyncSocket> foreign_socket_;
     71 
     72   // Shared memory wrapper used for transferring audio data to Read() callers.
     73   scoped_ptr<media::AudioBus> output_bus_;
     74 
     75   // Shared memory wrapper used for transferring audio data from Read() callers.
     76   scoped_ptr<media::AudioBus> input_bus_;
     77 
     78   // Maximum amount of audio data which can be transferred in one Read() call.
     79   int packet_size_;
     80 
     81   // Track the number of times the renderer missed its real-time deadline and
     82   // report a UMA stat during destruction.
     83   size_t renderer_callback_count_;
     84   size_t renderer_missed_callback_count_;
     85 
     86   DISALLOW_COPY_AND_ASSIGN(AudioSyncReader);
     87 };
     88 
     89 }  // namespace content
     90 
     91 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_SYNC_READER_H_
     92