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_SOUNDOUTPUTSTREAMINTERFACE_H_ 12 #define WEBRTC_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_ 13 14 #include "webrtc/base/constructormagic.h" 15 #include "webrtc/base/sigslot.h" 16 17 namespace rtc { 18 19 // Interface for outputting a stream to a playback device. 20 // Semantics and thread-safety of EnableBufferMonitoring()/ 21 // DisableBufferMonitoring() are the same as for rtc::Worker. 22 class SoundOutputStreamInterface { 23 public: 24 virtual ~SoundOutputStreamInterface() {} 25 26 // Enables monitoring the available buffer space on the current thread. 27 virtual bool EnableBufferMonitoring() = 0; 28 // Disables the monitoring. 29 virtual bool DisableBufferMonitoring() = 0; 30 31 // Write the given samples to the devices. If currently monitoring then this 32 // may only be called from the monitoring thread. 33 virtual bool WriteSamples(const void *sample_data, 34 size_t size) = 0; 35 36 // Retrieves the current output volume for this stream. Nominal range is 37 // defined by SoundSystemInterface::k(Max|Min)Volume, but values exceeding the 38 // max may be possible in some implementations. This call retrieves the actual 39 // volume currently in use by the OS, not a cached value from a previous 40 // (Get|Set)Volume() call. 41 virtual bool GetVolume(int *volume) = 0; 42 43 // Changes the output volume for this stream. Nominal range is defined by 44 // SoundSystemInterface::k(Max|Min)Volume. The effect of exceeding kMaxVolume 45 // is implementation-defined. 46 virtual bool SetVolume(int volume) = 0; 47 48 // Closes this stream object. If currently monitoring then this may only be 49 // called from the monitoring thread. 50 virtual bool Close() = 0; 51 52 // Get the latency of the stream. 53 virtual int LatencyUsecs() = 0; 54 55 // Notifies the producer of the available buffer space for writes. 56 // It fires continuously as long as the space is greater than zero. 57 // The first parameter is the amount of buffer space available for data to 58 // be written (i.e., the maximum amount of data that can be written right now 59 // with WriteSamples() without blocking). 60 // The 2nd parameter is the stream that is issuing the callback. 61 sigslot::signal2<size_t, SoundOutputStreamInterface *> SignalBufferSpace; 62 63 protected: 64 SoundOutputStreamInterface() {} 65 66 private: 67 DISALLOW_COPY_AND_ASSIGN(SoundOutputStreamInterface); 68 }; 69 70 } // namespace rtc 71 72 #endif // WEBRTC_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_ 73
