Android ToneGenerator startTone（）首次通話非常慢

Question

我反復調用ToneGenerator.startTone()發出短促的聲音。 但是在第一次通話時，它會阻塞很長一段時間。 因此，第一次爆發太長了。 這是一個例子：

成員變量：

private ToneGenerator mDTMFPlayer

在構造函數中：

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

在OnClickListener.onClick()啟動的Thread ：

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();

這是輸出，其中startTone()執行時間以毫秒為單位：

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

第一次通話阻塞了將近半秒鍾，對於我所需的時間來說太長了。 此后的任何呼叫都會使阻塞消失一段時間。 奇怪的是，如果我稍等一下再試一次，它又變慢了。 似乎有一段時間之后，封鎖再次出現。

請指教。

Answer 1

我認為AudioManager.STREAM_VOICE_CALL導致了此問題。 我設計的行為與您相似。 在我運行應用程序后，它對第一個startTone()調用的初始化時間很長。 如果我退出並進入應用程序，則可以快速處理所有3個通話。 但是，如果在應用啟動之前播放了一些系統聲音，它將顯示相同的“慢，快，快”結果。

所以我想這與流切換/阻塞有關，因為有了AudioManager.STREAM_NOTIFICATION ，我的設備只需要4-10毫秒。 也可以在此處閱讀更多信息： 低級別AudioManager的流類型之間有什么區別？

考慮以下代碼：

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();
}

輸出：

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  

順便說一句，如果您想研究相關的C代碼代碼，可以查看android_media_ToneGenerator.cpp ， ToneGenerator.h ， ToneGenerator.cpp AudioService.java