AudioPolicyManager::getDeviceForStrategy

最新推荐文章于 2025-07-14 22:27:15 发布

Damon_X

最新推荐文章于 2025-07-14 22:27:15 发布

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分类专栏： android audio

本文链接：https://blog.youkuaiyun.com/Damon_X/article/details/51668914

AudioPolicyManager的getDeviceForStrategy方法通过StreamType获取对应的Strategy，并在mOutputRoutes中查找匹配的Route设备。Strategy可以理解为一组具有相似行为的流类型。例如，AUDIO_STREAM_VOICE_CALL和AUDIO_STREAM_BLUETOOTH_SCO对应STRATEGY_PHONE，而AUDIO_STREAM_MUSIC和AUDIO_STREAM_SYSTEM则对应STRATEGY_MEDIA。

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getStrategy根据StreamType得到Strategy，AudioPolicyManager再从mOutputRoutes里查出Strategy和前面得到的Strategy相等的Route里面的Device

从以上可以看出， Strategy可以定义为：Group of stream types with the similar behavior。当然从getStrategyForStream函数的定义也可以看出来：

164 routing_strategy Engine::getStrategyForStream(audio_stream_type_t stream)
165 {
166 // stream to strategy mapping
167 switch (stream) {
168 case AUDIO_STREAM_VOICE_CALL:
169 case AUDIO_STREAM_BLUETOOTH_SCO:
170 return STRATEGY_PHONE;
171 case AUDIO_STREAM_RING:
172 case AUDIO_STREAM_ALARM:
173 return STRATEGY_SONIFICATION;
174 case AUDIO_STREAM_NOTIFICATION:
175 return STRATEGY_SONIFICATION_RESPECTFUL;
176 case AUDIO_STREAM_DTMF:
177 return STRATEGY_DTMF;
178 default:
179 ALOGE("unknown stream type %d", stream);
180 case AUDIO_STREAM_SYSTEM:
181 // NOTE: SYSTEM stream uses MEDIA strategy because muting music and switching outputs
182 // while key clicks are played produces a poor result
183 case AUDIO_STREAM_MUSIC:
184