Android Automotive（三）——CarAudioService（AndroidP）

最新推荐文章于 2025-04-07 14:17:03 发布

tudouhuashengmi

最新推荐文章于 2025-04-07 14:17:03 发布

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分类专栏： Android Audio 文章标签： android

本文链接：https://blog.youkuaiyun.com/tudouhuashengmi/article/details/113115210

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本文详细介绍了Android Automotive中的CarAudioService，包括类图、流程图和关键函数，如setupDynamicRouting、AudioManager::registerAudioPolicy、CarAudioService::setupVolumeGroups、AudioService::adjustSuggestedStreamVolume和CarAudioManager::setGroupVolume。文章深入探讨了动态路由配置、音量控制和音频策略的实现，展示了Android Automotive音频服务的工作原理。

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1. CarAudio

Google Automotive Audio: https://source.android.google.cn/devices/automotive/audio
configure-volume: https://source.android.google.cn/devices/automotive/audio/audio-control#configure-volume
configure-volume-groups: https://source.android.google.cn/devices/automotive/audio/audio-control#configure-volume-groups
configure-audio-devices: https://source.android.google.cn/devices/automotive/audio/audio-hal#configure-audio-devices

下图摘自上述地址：

2. CarAudioService

2.1 类图

2.2 流程图

2.3 构造函数

这里读取配置文件audioUseDynamicRouting确定是否使用动态Routing。

    public CarAudioService(Context context) {
        mContext = context;
        mTelephonyManager = (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);
        mAudioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
        mUseDynamicRouting = mContext.getResources().getBoolean(R.bool.audioUseDynamicRouting);
    }

2.4 setupDynamicRouting

当mUseDynamicRouting为true时，将调用setupDynamicRouting函数；该函数里会创建一个AudioPolicy ，并通过mAudioManager.registerAudioPolicy函数注册该AudioPolicy。

   private void setupDynamicRouting() {
        final IAudioControl audioControl = getAudioControl();
        if (audioControl == null) {
            return;
        }
        AudioPolicy audioPolicy = getDynamicAudioPolicy(audioControl);
        int r = mAudioManager.registerAudioPolicy(audioPolicy);
        if (r != AudioManager.SUCCESS) {
            throw new RuntimeException("registerAudioPolicy failed " + r);
        }
        mAudioPolicy = audioPolicy;
    }

2.5 AudioManager::registerAudioPolicy

    public int registerAudioPolicy(@NonNull AudioPolicy policy) {
        if (policy == null) {
            throw new IllegalArgumentException("Illegal null AudioPolicy argument");
        }
        final IAudioService service = getService();
        try {
            String regId = service.registerAudioPolicy(policy.getConfig(), policy.cb(),
                    policy.hasFocusListener(), policy.isFocusPolicy(), policy.isVolumeController());
            if (regId =&#

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