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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/process/process.h"
      9 #include "base/sync_socket.h"
     10 #include "base/synchronization/lock.h"
     11 #include "base/time/time.h"
     12 #include "media/audio/audio_output_controller.h"
     13 #include "media/base/audio_bus.h"
     14 
     15 #if defined(OS_POSIX)
     16 #include "base/file_descriptor_posix.h"
     17 #endif
     18 
     19 namespace base {
     20 class SharedMemory;
     21 }
     22 
     23 namespace content {
     24 
     25 // A AudioOutputController::SyncReader implementation using SyncSocket. This
     26 // is used by AudioOutputController to provide a low latency data source for
     27 // transmitting audio packets between the browser process and the renderer
     28 // process.
     29 class AudioSyncReader : public media::AudioOutputController::SyncReader {
     30  public:
     31   AudioSyncReader(base::SharedMemory* shared_memory,
     32                   const media::AudioParameters& params);
     33 
     34   virtual ~AudioSyncReader();
     35 
     36   // media::AudioOutputController::SyncReader implementations.
     37   virtual void UpdatePendingBytes(uint32 bytes) OVERRIDE;
     38   virtual void Read(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   // Blocks until data is ready for reading or a timeout expires.  Returns false
     51   // if an error or timeout occurs.
     52   bool WaitUntilDataIsReady();
     53 
     54   const base::SharedMemory* const shared_memory_;
     55 
     56   // Mutes all incoming samples. This is used to prevent audible sound
     57   // during automated testing.
     58   const bool mute_audio_;
     59 
     60   // Socket for transmitting audio data.
     61   scoped_ptr<base::CancelableSyncSocket> socket_;
     62 
     63   // Socket to be used by the renderer. The reference is released after
     64   // PrepareForeignSocketHandle() is called and ran successfully.
     65   scoped_ptr<base::CancelableSyncSocket> foreign_socket_;
     66 
     67   // Shared memory wrapper used for transferring audio data to Read() callers.
     68   scoped_ptr<media::AudioBus> output_bus_;
     69 
     70   // Maximum amount of audio data which can be transferred in one Read() call.
     71   const int packet_size_;
     72 
     73   // Track the number of times the renderer missed its real-time deadline and
     74   // report a UMA stat during destruction.
     75   size_t renderer_callback_count_;
     76   size_t renderer_missed_callback_count_;
     77 
     78   // The maximum amount of time to wait for data from the renderer.  Calculated
     79   // from the parameters given at construction.
     80   const base::TimeDelta maximum_wait_time_;
     81 
     82   // The index of the audio buffer we're expecting to be sent from the renderer;
     83   // used to block with timeout for audio data.
     84   uint32 buffer_index_;
     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