java – Android ToneGenerator startTone()在第一次调用时非常慢

我正在多次调用ToneGenerator.startTone()来发出短促的声音.但在第一次通话时,它会长时间阻挡.所以第一次爆发太长了.这是一个例子：

成员变量：

private ToneGenerator mDTmfplayer

在构造函数中：

mDTmfplayer = new ToneGenerator(AudioManager.STREAM_VOICE_CALL, TONE_RELATIVE_VOLUME);

在由OnClickListener.onClick()启动的线程中：

long startTime = System.currentTimeMillis();
mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
Log.d(TAG,"After 1st: " + (System.currentTimeMillis() - startTime));
try { Thread.sleep(160); } catch (InterruptedException e) { }
mDTmfplayer.stopTone();

startTime = System.currentTimeMillis();
mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
Log.d(TAG,"After 2nd: " + (System.currentTimeMillis() - startTime));
try { Thread.sleep(160); } catch (InterruptedException e) { }
mDTmfplayer.stopTone();

startTime = System.currentTimeMillis();
mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
Log.d(TAG,"After 3rd: " + (System.currentTimeMillis() - startTime));
try { Thread.sleep(160); } catch (InterruptedException e) { }
mDTmfplayer.stopTone();

这是输出,执行时间为startTone(),以毫秒为单位：

11-16 18:07:35.885 16927-17977/com.my.project D/Ring: After 1st: 454
11-16 18:07:36.502 16927-17977/com.my.project D/Ring: After 2nd: 0
11-16 18:07:36.672 16927-17977/com.my.project D/Ring: After 3rd: 1

第一个电话是阻塞了将近半秒,这对于我需要的时间太长了.之后的任何调用都会使阻塞消失一段时间.有点奇怪的是,如果我再等一下再试一次,那就再慢了.似乎有一段时间后阻塞回来了.

请指教.

解决方法:

我认为AudioManager.STREAM_VOICE_CALL导致了这一点.我的设计上的行为与你的相似.在我运行app之后,它有第一次startTone()调用的初始化.如果我退出并输入应用程序,它可以快速进行所有3次通话.但如果在应用程序启动之前播放一些系统声音,它将显示相同的“慢,快,快”结果.

所以我认为它与流切换/阻塞有关,因为使用AudioManager.STREAM_NOTIFICATION,我的设备只需要4-10毫秒.也可以在这里阅读更多信息：What is the difference between AudioManager’s stream types at low level?

考虑以下代码：

for (int i = -1; i < 10; i++) {
    System.out.println("AudioSystem stream " + i);
    mDTmfplayer = new ToneGenerator(i, TONE_RELATIVE_VOLUME);
    long startTime = System.currentTimeMillis();
    mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
    Log.d(TAG, "After 1st: " + (System.currentTimeMillis() - startTime));
    try {Thread.sleep(160);} catch (InterruptedException e) {}
    mDTmfplayer.stopTone();

    startTime = System.currentTimeMillis();
    mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
    Log.d(TAG, "After 2nd: " + (System.currentTimeMillis() - startTime));
    try {Thread.sleep(160);} catch (InterruptedException e) {}
    mDTmfplayer.stopTone();

    startTime = System.currentTimeMillis();
    mDTmfplayer.startTone(ToneGenerator.TONE_DTMF_0);
    Log.d(TAG, "After 3rd: " + (System.currentTimeMillis() - startTime));
    try {Thread.sleep(160);} catch (InterruptedException e) {}
    mDTmfplayer.stopTone();
    mDTmfplayer.release();
}

输出：

I/System.out: AudioSystem stream -1 STREAM_DEFAULT
D/com.example.MainActivity: After 1st: 8
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 0 STREAM_VOICE_CALL
D/com.example.MainActivity: After 1st: 325
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 1 STREAM_SYstem
D/com.example.MainActivity: After 1st: 17
D/com.example.MainActivity: After 2nd: 2
D/com.example.MainActivity: After 3rd: 3
I/System.out: AudioSystem stream 2 STREAM_RING
D/com.example.MainActivity: After 1st: 28
D/com.example.MainActivity: After 2nd: 2
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 3 STREAM_MUSIC
D/com.example.MainActivity: After 1st: 19
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 4 STREAM_ALARM
D/com.example.MainActivity: After 1st: 28
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 5 STREAM_NOTIFICATION
D/com.example.MainActivity: After 1st: 16
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 6 STREAM_BLUetoOTH_SCO
D/com.example.MainActivity: After 1st: 332
D/com.example.MainActivity: After 2nd: 2
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 7 STREAM_SYstem_ENFORCED
D/com.example.MainActivity: After 1st: 324
D/com.example.MainActivity: After 2nd: 1
D/com.example.MainActivity: After 3rd: 1
I/System.out: AudioSystem stream 8 STREAM_DTMF
D/com.example.MainActivity: After 1st: 26
D/com.example.MainActivity: After 2nd: 2
D/com.example.MainActivity: After 3rd: 4
I/System.out: AudioSystem stream 9 STREAM_TTS
D/com.example.MainActivity: After 1st: 12
D/com.example.MainActivity: After 2nd: 4
D/com.example.MainActivity: After 3rd: 2

顺便说一句,如果你想研究相关的C代码,你可以看看android_media_ToneGenerator.cpp,ToneGenerator.h,ToneGenerator.cpp AudioService.java

java – Android ToneGenerator startTone()在第一次调用时非常慢

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