AudioPolicyInterface.h revision f163f3d600c056de0bdca6d12555a0225f76ec9a 
1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_AUDIOPOLICYINTERFACE_H
18#define ANDROID_AUDIOPOLICYINTERFACE_H
19
20#include <media/AudioSystem.h>
21#include <media/ToneGenerator.h>
22#include <utils/String8.h>
23
24namespace android {
25
26
27// ----------------------------------------------------------------------------
28
29// The AudioPolicyInterface and AudioPolicyClientInterface classes define the communication interfaces
30// between the platform specific audio policy manager and Android generic audio policy manager.
31// The platform specific audio policy manager must implement methods of the AudioPolicyInterface class.
32// This implementation makes use of the AudioPolicyClientInterface to control the activity and
33// configuration of audio input and output streams.
34//
35// The platform specific audio policy manager is in charge of the audio routing and volume control
36// policies for a given platform.
37// The main roles of this module are:
38//   - keep track of current system state (removable device connections, phone state, user requests...).
39//   System state changes and user actions are notified to audio policy manager with methods of the AudioPolicyInterface.
40//   - process getOutput() queries received when AudioTrack objects are created: Those queries
41//   return a handler on an output that has been selected, configured and opened by the audio policy manager and that
42//   must be used by the AudioTrack when registering to the AudioFlinger with the createTrack() method.
43//   When the AudioTrack object is released, a putOutput() query is received and the audio policy manager can decide
44//   to close or reconfigure the output depending on other streams using this output and current system state.
45//   - similarly process getInput() and putInput() queries received from AudioRecord objects and configure audio inputs.
46//   - process volume control requests: the stream volume is converted from an index value (received from UI) to a float value
47//   applicable to each output as a function of platform specific settings and current output route (destination device). It
48//   also make sure that streams are not muted if not allowed (e.g. camera shutter sound in some countries).
49//
50// The platform specific audio policy manager is provided as a shared library by platform vendors (as for libaudio.so)
51// and is linked with libaudioflinger.so
52
53
54//    Audio Policy Manager Interface
55class AudioPolicyInterface
56{
57
58public:
59    virtual ~AudioPolicyInterface() {}
60    //
61    // configuration functions
62    //
63
64    // indicate a change in device connection status
65    virtual status_t setDeviceConnectionState(AudioSystem::audio_devices device,
66                                          AudioSystem::device_connection_state state,
67                                          const char *device_address) = 0;
68    // retreive a device connection status
69    virtual AudioSystem::device_connection_state getDeviceConnectionState(AudioSystem::audio_devices device,
70                                                                          const char *device_address) = 0;
71    // indicate a change in phone state. Valid phones states are defined by AudioSystem::audio_mode
72    virtual void setPhoneState(int state) = 0;
73    // indicate a change in ringer mode
74    virtual void setRingerMode(uint32_t mode, uint32_t mask) = 0;
75    // force using a specific device category for the specified usage
76    virtual void setForceUse(AudioSystem::force_use usage, AudioSystem::forced_config config) = 0;
77    // retreive current device category forced for a given usage
78    virtual AudioSystem::forced_config getForceUse(AudioSystem::force_use usage) = 0;
79    // set a system property (e.g. camera sound always audible)
80    virtual void setSystemProperty(const char* property, const char* value) = 0;
81
82
83    //
84    // Audio routing query functions
85    //
86
87    // request an output appriate for playback of the supplied stream type and parameters
88    virtual audio_io_handle_t getOutput(AudioSystem::stream_type stream,
89                                        uint32_t samplingRate = 0,
90                                        uint32_t format = AudioSystem::FORMAT_DEFAULT,
91                                        uint32_t channels = 0,
92                                        AudioSystem::output_flags flags = AudioSystem::OUTPUT_FLAG_INDIRECT) = 0;
93    // indicates to the audio policy manager that the output starts being used by corresponding stream.
94    virtual status_t startOutput(audio_io_handle_t output, AudioSystem::stream_type stream) = 0;
95    // indicates to the audio policy manager that the output stops being used by corresponding stream.
96    virtual status_t stopOutput(audio_io_handle_t output, AudioSystem::stream_type stream) = 0;
97    // releases the output.
98    virtual void releaseOutput(audio_io_handle_t output) = 0;
99
100    // request an input appriate for record from the supplied device with supplied parameters.
101    virtual audio_io_handle_t getInput(int inputSource,
102                                    uint32_t samplingRate = 0,
103                                    uint32_t Format = AudioSystem::FORMAT_DEFAULT,
104                                    uint32_t channels = 0,
105                                    AudioSystem::audio_in_acoustics acoustics = (AudioSystem::audio_in_acoustics)0) = 0;
106    // indicates to the audio policy manager that the input starts being used.
107    virtual status_t startInput(audio_io_handle_t input) = 0;
108    // indicates to the audio policy manager that the input stops being used.
109    virtual status_t stopInput(audio_io_handle_t input) = 0;
110    // releases the input.
111    virtual void releaseInput(audio_io_handle_t input) = 0;
112
113    //
114    // volume control functions
115    //
116
117    // initialises stream volume conversion parameters by specifying volume index range.
118    virtual void initStreamVolume(AudioSystem::stream_type stream,
119                                      int indexMin,
120                                      int indexMax) = 0;
121
122    // sets the new stream volume at a level corresponding to the supplied index
123    virtual status_t setStreamVolumeIndex(AudioSystem::stream_type stream, int index) = 0;
124    // retreive current volume index for the specified stream
125    virtual status_t getStreamVolumeIndex(AudioSystem::stream_type stream, int *index) = 0;
126};
127
128
129// Audio Policy client Interface
130class AudioPolicyClientInterface
131{
132public:
133    virtual ~AudioPolicyClientInterface() {}
134
135    //
136    // Audio output Control functions
137    //
138
139    // opens an audio output with the requested parameters. The parameter values can indicate to use the default values
140    // in case the audio policy manager has no specific requirements for the output being opened.
141    // When the function returns, the parameter values reflect the actual values used by the audio hardware output stream.
142    // The audio policy manager can check if the proposed parameters are suitable or not and act accordingly.
143    virtual audio_io_handle_t openOutput(uint32_t *pDevices,
144                                    uint32_t *pSamplingRate,
145                                    uint32_t *pFormat,
146                                    uint32_t *pChannels,
147                                    uint32_t *pLatencyMs,
148                                    AudioSystem::output_flags flags) = 0;
149    // creates a special output that is duplicated to the two outputs passed as arguments. The duplication is performed by
150    // a special mixer thread in the AudioFlinger.
151    virtual audio_io_handle_t openDuplicateOutput(audio_io_handle_t output1, audio_io_handle_t output2) = 0;
152    // closes the output stream
153    virtual status_t closeOutput(audio_io_handle_t output) = 0;
154    // suspends the output. When an output is suspended, the corresponding audio hardware output stream is placed in
155    // standby and the AudioTracks attached to the mixer thread are still processed but the output mix is discarded.
156    virtual status_t suspendOutput(audio_io_handle_t output) = 0;
157    // restores a suspended output.
158    virtual status_t restoreOutput(audio_io_handle_t output) = 0;
159
160    //
161    // Audio input Control functions
162    //
163
164    // opens an audio input
165    virtual audio_io_handle_t openInput(uint32_t *pDevices,
166                                    uint32_t *pSamplingRate,
167                                    uint32_t *pFormat,
168                                    uint32_t *pChannels,
169                                    uint32_t acoustics) = 0;
170    // closes an audio input
171    virtual status_t closeInput(audio_io_handle_t input) = 0;
172    //
173    // misc control functions
174    //
175
176    // set a stream volume for a particular output. For the same user setting, a given stream type can have different volumes
177    // for each output (destination device) it is attached to.
178    virtual status_t setStreamVolume(AudioSystem::stream_type stream, float volume, audio_io_handle_t output, int delayMs = 0) = 0;
179
180    // reroute a given stream type to the specified output
181    virtual status_t setStreamOutput(AudioSystem::stream_type stream, audio_io_handle_t output) = 0;
182
183    // function enabling to send proprietary informations directly from audio policy manager to audio hardware interface.
184    virtual void setParameters(audio_io_handle_t ioHandle, const String8& keyValuePairs, int delayMs = 0) = 0;
185    // function enabling to receive proprietary informations directly from audio hardware interface to audio policy manager.
186    virtual String8 getParameters(audio_io_handle_t ioHandle, const String8& keys) = 0;
187
188    // request the playback of a tone on the specified stream: used for instance to replace notification sounds when playing
189    // over a telephony device during a phone call.
190    virtual status_t startTone(ToneGenerator::tone_type tone, AudioSystem::stream_type stream) = 0;
191    virtual status_t stopTone() = 0;
192
193    // set down link audio volume.
194    virtual status_t setVoiceVolume(float volume, int delayMs = 0) = 0;
195};
196
197extern "C" AudioPolicyInterface* createAudioPolicyManager(AudioPolicyClientInterface *clientInterface);
198extern "C" void destroyAudioPolicyManager(AudioPolicyInterface *interface);
199
200
201}; // namespace android
202
203#endif // ANDROID_AUDIOPOLICYINTERFACE_H
204