据我所知,这是飞利浦Android TV用户的常见问题(例如

this篇中的第22页,或

that讨论).

一般来说,您的任务的模板是跟踪插入/拔出事件和“系统/音乐”音频流(或媒体按钮按下)的音量的服务,而不是对“有线耳机”音频“流”进行相应的更改(没有这样的流在“标准”Android中,但显然

类似于

“Android Philips”级别的东西.问题是,似乎不可能只使用没有“飞利浦Android TV API”的Android SDK来改变音量“有线耳机”音频流级别(可能它不是公共的).

“VolumeTrackingService”的模板源代码可能是这样的：

public class VolumeTrackingService extends Service {

private static final String TAG = VolumeTrackingService.class.getSimpleName();

public static final String ACTION_START = "VolumeTrackingService.ACTION_START";

public static final String ACTION_STOP = "VolumeTrackingService.ACTION_STOP";

HeadsetPlugIntentReceiver mHeadsetPlugReceiver;

private static boolean mHeadsetPlugged = false;

private SettingsContentObserver mSettingsContentObserver;

@Nullable

@Override

public IBinder onBind(Intent intent) {

return null;

}

@Override

public void onCreate() {

super.onCreate();

mHeadsetPlugReceiver = new HeadsetPlugIntentReceiver();

registerReceiver(mHeadsetPlugReceiver,new IntentFilter(Intent.ACTION_HEADSET_PLUG));

mSettingsContentObserver = new SettingsContentObserver(new Handler());

getApplicationContext().getContentResolver().registerContentObserver(android.provider.Settings.System.CONTENT_URI,true,mSettingsContentObserver);

}

@Override

public void onDestroy() {

getApplicationContext().getContentResolver().unregisterContentObserver(mSettingsContentObserver);

unregisterReceiver(mHeadsetPlugReceiver);

super.onDestroy();

}

@Override

public int onStartCommand(Intent intent,int flags,int startId) {

if (intent != null) {

String actionRequested = intent.getAction();

if (ACTION_START.equals(actionRequested)) {

} else if (ACTION_STOP.equals(actionRequested)) {

stopSelf();

}

}

return START_STICKY;

}

private int getSystemVolumeInPercentage() {

AudioManager audioManager = (AudioManager) getSystemService(Context.AUdio_SERVICE);

final int streamVolumeMax = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);

final int streamVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);

return 100 * streamVolume / streamVolumeMax;

}

private void setHeadphonesVolume(int volumeInPercentage) {

// there should be magic of wired headphones volume level changing

}

private void processVolumeChanges() {

if (mHeadsetPlugged) {

int systemVolumeInPercentage = getSystemVolumeInPercentage();

setHeadphonesVolume(systemVolumeInPercentage);

}

}

public class SettingsContentObserver extends ContentObserver {

public SettingsContentObserver(Handler handler) {

super(handler);

}

@Override

public boolean deliverSelfNotifications() {

return super.deliverSelfNotifications();

}

@Override

public void onChange(boolean selfChange) {

super.onChange(selfChange);

if (mHeadsetPlugged ) {

processVolumeChanges();

}

}

}

public class HeadsetPlugIntentReceiver extends android.content.BroadcastReceiver {

@Override

public void onReceive(Context ctx,Intent intent) {

if (intent.getAction().equals(android.media.AudioManager.ACTION_HEADSET_PLUG)) {

mHeadsetPlugged = intent.getIntExtra("state",0) == 1;

}

}

}

}

不幸的是,它没有解决主要问题：改变有线耳机的音量水平(如果没有“飞利浦Android TV API”,可能是不可能的).

但是如果你的环绕声系统有遥控器你可以做一些解决方法：在上述服务中模拟音响系统遥控器命令,并通过连接到飞利浦49PUS6401 Android TV的USB主机的红外加密狗发送.