android 源码分析打开mic

1、demo

AudioManager audioManager = (AudioManager)getSystemService("audio");
audioManager.setMode(AudioManager.STREAM_MUSIC);//设置声音模式
audioManager.setMicrophoneMute(true); //打开麦克风

权限:<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

2、java层

<1>frameworks/base/media/java/android/media/AudioManager.java

public void setMicrophoneMute(boolean on){

IAudioService service = getService();
service.setMicrophoneMute(on, mContext.getOpPackageName()); }

<2>frameworks/base/media/java/android/media/AudioSystem.java

public static native int muteMicrophone(boolean on);

3、Native层

<1>frameworks/base/core/jni/android_media_AudioSystem.cpp

(1)static JNINativeMethodgMethods[] ={

{"muteMicrophone", "(Z)I", (void *)android_media_AudioSystem_muteMicrophone},};

(2)static jint android_media_AudioSystem_muteMicrophone(JNIEnv *env, jobject thiz, jboolean on) { return (jint) check_AudioSystem_Command(AudioSystem::muteMicrophone(on));

}

<2>frameworks/av/media/libmedia/AudioSystem.cpp

status_t AudioSystem::muteMicrophone(bool state) { const sp<IAudioFlinger>&af = AudioSystem::get_audio_flinger();
return af->setMicMute(state); }

<3>Binder的Client端Bp层，真正实现的部分在服务端的Bn层

frameworks/av/media/libmedia/IaudioFlinger.cpp

class BpAudioFlinger : public BpInterface<IAudioFlinger>{

         virtual status_t setMicMute(bool state) {
           Parcel data, reply;
          data.writeInterfaceToken(IAudioFlinger::getInterfaceDescriptor());
          data.writeInt32(state);
          remote()->transact(SET_MIC_MUTE, data, &reply);
          return reply.readInt32();
         }

};

IMPLEMENT_META_INTERFACE(AudioFlinger, "android.media.IAudioFlinger");

     status_t BnAudioFlinger::onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags){
      case SET_MIC_MUTE: {
            CHECK_INTERFACE(IAudioFlinger, data, reply);
            reply->writeInt32( setMicMute(state) ); //发送给Bn服务端
            return NO_ERROR;}
            break;

}

<4>Binder服务端的Bn层，真正实现的部分

frameworks/av/services/audioflinger/AudioFlinger.cpp

AudioFlinger::AudioFlinger() :BnAudioFlinger(){//构造函数

       }
     status_t AudioFlinger::setMicMute(bool state){
       status_t result = dev->set_mic_mute(dev, state);//调用HAL层
     }

4、HAL层

hardware/rockchip/audio/tinyalsa_hal/audio_hw.c

    <1>static int adev_open(const hw_module_t* module, const char* name, hw_device_t** device)
    {
        struct audio_device *adev;
        adev->hw_device.set_mic_mute = adev_set_mic_mute;
    }

    static int adev_set_mic_mute(struct audio_hw_device *dev, bool state)
    {
       struct audio_device *adev = (struct audio_device *)dev;
       adev->mic_mute = state;
       return 0;
   }

<2>打开audio设备节点操作

external/tinyalsa/pcm.c

struct pcm *pcm_open(unsigned int card, unsigned int device, unsigned int flags, struct pcm_config *config)

{
snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device, flags & PCM_IN ? 'c' : 'p');

pcm->fd =open(fn, O_RDWR);
}

5、Kernel层

kernel/sound/soc/rockchip/rk30_fpga192k.c

     static int rk30_hw_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params)
    {
       snd_soc_dai_set_sysclk(cpu_dai, 0, pll_out, 1);
       snd_soc_dai_set_clkdiv(cpu_dai, ROCKCHIP_DIV_BCLK,div_bclk);
       snd_soc_dai_set_clkdiv(cpu_dai, ROCKCHIP_DIV_MCLK, div_mclk);
   }

android 源码分析打开mic

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