项目场景：

Android TV，Android Q
1、在Launcher下通过遥控器按mute，然后再按音量+，之后系统音无声音（按键音）
2、在Launcher下通过遥控器按mute，然后再按mute，之后系统音是正常有声音的

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问题描述：

在Launcher下通过遥控器按mute，然后再按音量+，之后系统音无声音（按键音）

frameworks/base/services/core/java/com/android/server/audio/AudioService.java

	/* 这里是TV平台所以是STREAM_VOLUME_ALIAS_TELEVISION的别称数组 */
    private final int[] STREAM_VOLUME_ALIAS_TELEVISION = new int[] {
        AudioSystem.STREAM_MUSIC,       // STREAM_VOICE_CALL
        AudioSystem.STREAM_MUSIC,       // STREAM_SYSTEM
        AudioSystem.STREAM_MUSIC,       // STREAM_RING
        AudioSystem.STREAM_MUSIC,       // STREAM_MUSIC
        AudioSystem.STREAM_MUSIC,       // STREAM_ALARM
        AudioSystem.STREAM_MUSIC,       // STREAM_NOTIFICATION
        AudioSystem.STREAM_BLUETOOTH_SCO,       // STREAM_BLUETOOTH_SCO
        AudioSystem.STREAM_MUSIC,       // STREAM_SYSTEM_ENFORCED
        AudioSystem.STREAM_MUSIC,       // STREAM_DTMF
        AudioSystem.STREAM_MUSIC,       // STREAM_TTS
        AudioSystem.STREAM_MUSIC,       // STREAM_ACCESSIBILITY
        AudioSystem.STREAM_MUSIC        // STREAM_ASSISTANT
    };
...
protected void adjustStreamVolume(int streamType, int direction, int flags,
        String callingPackage, String caller, int uid) {
...
	if (isMuteAdjust) {
	    boolean state;
	    if (direction == AudioManager.ADJUST_TOGGLE_MUTE) {
	        state = !streamState.mIsMuted;
	    } else {
	        state = direction == AudioManager.ADJUST_MUTE;
	    }
	    if (streamTypeAlias == AudioSystem.STREAM_MUSIC) {
	        setSystemAudioMute(state);
	    }
	    /* 当设置music的type音量mute和unmute时，将所有别名跟music一致的stream都在这里设置mute和unmute */
	    for (int stream = 0; stream < mStreamStates.length; stream++) {
	        if (streamTypeAlias == mStreamVolumeAlias[stream]) {
	            if (!(readCameraSoundForced() && (mStreamStates[stream].getStreamType()
	                            == AudioSystem.STREAM_SYSTEM_ENFORCED))) {
	                mStreamStates[stream].mute(state);
	            }
	        }
	    }
	} else if ((direction == AudioManager.ADJUST_RAISE) &&
	        !checkSafeMediaVolume(streamTypeAlias, aliasIndex + step, device)) {
	    Log.e(TAG, "adjustStreamVolume() safe volume index = " + oldIndex);
	    mVolumeController.postDisplaySafeVolumeWarning(flags);
	} else if (((device & mFullVolumeDevices) == 0)
	        && (streamState.adjustIndex(direction * step, device, caller)
	                || streamState.mIsMuted)) {
	    // Post message to set system volume (it in turn will post a
	    // message to persist).
	    if (streamState.mIsMuted) {
	        // Unmute the stream if it was previously muted
	        if (direction == AudioManager.ADJUST_RAISE) {
	            // unmute immediately for volume up
	            /* 当设置音量+时，此处不会将所有别名跟music一致的stream unmute。 问题单在这。 */
	            streamState.mute(false);
	        } else if (direction == AudioManager.ADJUST_LOWER) {
	            if (mIsSingleVolume) {
	                sendMsg(mAudioHandler, MSG_UNMUTE_STREAM, SENDMSG_QUEUE,
	                        streamTypeAlias, flags, null, UNMUTE_STREAM_DELAY);
	            }
	        }
	    }
	    sendMsg(mAudioHandler,
	            MSG_SET_DEVICE_VOLUME,
	            SENDMSG_QUEUE,
	            device,
	            0,
	            streamState,
	            0);
	}

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原因分析：

Google的STREAM_VOLUME_ALIAS_TELEVISION数组中system stream默认是follow music的，但是在设置音量+时，不会将所有别名跟music一致的stream unmute。导致用户通过音量+无法unmute system的系统音。

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解决方案：

TV产品不允许用户通过遥控器设置System type的音量。 将STREAM_VOLUME_ALIAS_TELEVISION数组中的

AudioSystem.STREAM_MUSIC,       // STREAM_SYSTEM

修改为

AudioSystem.STREAM_SYSTEM,       // STREAM_SYSTEM

本文地址：https://blog.csdn.net/u013120422/article/details/111035549