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      1 /*
      2  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_SOUND_SOUNDINPUTSTREAMINTERFACE_H_
     12 #define WEBRTC_SOUND_SOUNDINPUTSTREAMINTERFACE_H_
     13 
     14 #include "webrtc/base/constructormagic.h"
     15 #include "webrtc/base/sigslot.h"
     16 
     17 namespace rtc {
     18 
     19 // Interface for consuming an input stream from a recording device.
     20 // Semantics and thread-safety of StartReading()/StopReading() are the same as
     21 // for rtc::Worker.
     22 class SoundInputStreamInterface {
     23  public:
     24   virtual ~SoundInputStreamInterface() {}
     25 
     26   // Starts the reading of samples on the current thread.
     27   virtual bool StartReading() = 0;
     28   // Stops the reading of samples.
     29   virtual bool StopReading() = 0;
     30 
     31   // Retrieves the current input volume for this stream. Nominal range is
     32   // defined by SoundSystemInterface::k(Max|Min)Volume, but values exceeding the
     33   // max may be possible in some implementations. This call retrieves the actual
     34   // volume currently in use by the OS, not a cached value from a previous
     35   // (Get|Set)Volume() call.
     36   virtual bool GetVolume(int *volume) = 0;
     37 
     38   // Changes the input volume for this stream. Nominal range is defined by
     39   // SoundSystemInterface::k(Max|Min)Volume. The effect of exceeding kMaxVolume
     40   // is implementation-defined.
     41   virtual bool SetVolume(int volume) = 0;
     42 
     43   // Closes this stream object. If currently reading then this may only be
     44   // called from the reading thread.
     45   virtual bool Close() = 0;
     46 
     47   // Get the latency of the stream.
     48   virtual int LatencyUsecs() = 0;
     49 
     50   // Notifies the consumer of new data read from the device.
     51   // The first parameter is a pointer to the data read, and is only valid for
     52   // the duration of the call.
     53   // The second parameter is the amount of data read in bytes (i.e., the valid
     54   // length of the memory pointed to).
     55   // The 3rd parameter is the stream that is issuing the callback.
     56   sigslot::signal3<const void *, size_t,
     57       SoundInputStreamInterface *> SignalSamplesRead;
     58 
     59  protected:
     60   SoundInputStreamInterface() {}
     61 
     62  private:
     63   DISALLOW_COPY_AND_ASSIGN(SoundInputStreamInterface);
     64 };
     65 
     66 }  // namespace rtc
     67 
     68 #endif  // WEBRTC_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_
     69