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_SOUNDSYSTEMINTERFACE_H_ 12 #define WEBRTC_SOUND_SOUNDSYSTEMINTERFACE_H_ 13 14 #include <vector> 15 16 #include "webrtc/base/constructormagic.h" 17 18 namespace rtc { 19 20 class SoundDeviceLocator; 21 class SoundInputStreamInterface; 22 class SoundOutputStreamInterface; 23 24 // Interface for a platform's sound system. 25 // Implementations must guarantee thread-safety for at least the following use 26 // cases: 27 // 1) Concurrent enumeration and opening of devices from different threads. 28 // 2) Concurrent use of different Sound(Input|Output)StreamInterface 29 // instances from different threads (but concurrent use of the _same_ one from 30 // different threads need not be supported). 31 class SoundSystemInterface { 32 public: 33 typedef std::vector<SoundDeviceLocator *> SoundDeviceLocatorList; 34 35 enum SampleFormat { 36 // Only one supported sample format at this time. 37 // The values here may be used in lookup tables, so they shouldn't change. 38 FORMAT_S16LE = 0, 39 }; 40 41 enum Flags { 42 // Enable reporting the current stream latency in 43 // Sound(Input|Output)StreamInterface. See those classes for more details. 44 FLAG_REPORT_LATENCY = (1 << 0), 45 }; 46 47 struct OpenParams { 48 // Format for the sound stream. 49 SampleFormat format; 50 // Sampling frequency in hertz. 51 unsigned int freq; 52 // Number of channels in the PCM stream. 53 unsigned int channels; 54 // Misc flags. Should be taken from the Flags enum above. 55 int flags; 56 // Desired latency, measured as number of bytes of sample data 57 int latency; 58 }; 59 60 // Special values for the "latency" field of OpenParams. 61 // Use this one to say you don't care what the latency is. The sound system 62 // will optimize for other things instead. 63 static const int kNoLatencyRequirements = -1; 64 // Use this one to say that you want the sound system to pick an appropriate 65 // small latency value. The sound system may pick the minimum allowed one, or 66 // a slightly higher one in the event that the true minimum requires an 67 // undesirable trade-off. 68 static const int kLowLatency = 0; 69 70 // Max value for the volume parameters for Sound(Input|Output)StreamInterface. 71 static const int kMaxVolume = 255; 72 // Min value for the volume parameters for Sound(Input|Output)StreamInterface. 73 static const int kMinVolume = 0; 74 75 // Helper for clearing a locator list and deleting the entries. 76 static void ClearSoundDeviceLocatorList(SoundDeviceLocatorList *devices); 77 ~SoundSystemInterface()78 virtual ~SoundSystemInterface() {} 79 80 virtual bool Init() = 0; 81 virtual void Terminate() = 0; 82 83 // Enumerates the available devices. (Any pre-existing locators in the lists 84 // are deleted.) 85 virtual bool EnumeratePlaybackDevices(SoundDeviceLocatorList *devices) = 0; 86 virtual bool EnumerateCaptureDevices(SoundDeviceLocatorList *devices) = 0; 87 88 // Gets a special locator for the default device. 89 virtual bool GetDefaultPlaybackDevice(SoundDeviceLocator **device) = 0; 90 virtual bool GetDefaultCaptureDevice(SoundDeviceLocator **device) = 0; 91 92 // Opens the given device, or returns NULL on error. 93 virtual SoundOutputStreamInterface *OpenPlaybackDevice( 94 const SoundDeviceLocator *device, 95 const OpenParams ¶ms) = 0; 96 virtual SoundInputStreamInterface *OpenCaptureDevice( 97 const SoundDeviceLocator *device, 98 const OpenParams ¶ms) = 0; 99 100 // A human-readable name for this sound system. 101 virtual const char *GetName() const = 0; 102 103 protected: SoundSystemInterface()104 SoundSystemInterface() {} 105 106 private: 107 RTC_DISALLOW_COPY_AND_ASSIGN(SoundSystemInterface); 108 }; 109 110 } // namespace rtc 111 112 #endif // WEBRTC_SOUND_SOUNDSYSTEMINTERFACE_H_ 113