我三天前开始学习Android编程,今天想使用一些Android API的类来做一些更困难的事情。
我找到了Visualizer类,但是第一次尝试时遇到了问题。我在不同的论坛上读到许多帖子,这些帖子中的人们遇到了相同的问题:无法初始化可视化引擎。
我在Manifest.xml文件中添加了所需的uses-permission。
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="org.program.fourier"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".mainFFT"
android:label="@string/title_activity_main_fft" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
接下来我尝试修复这个问题,但是我做不到。 这是我的完整代码:
package org.program.fourier;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.NavUtils;
import android.media.audiofx.Visualizer;
import android.media.audiofx.Visualizer.OnDataCaptureListener;
import android.media.MediaPlayer;
import android.media.AudioManager;
public class mainFFT extends Activity {
MediaPlayer mPlayer;
Visualizer vis;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_fft);
mPlayer = MediaPlayer.create(this, R.raw.sight);
mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
try
{
mPlayer.prepare();
}
catch(Exception ex){ Log.w("ExCePtIoN", ex+""); }
try
{
vis = new Visualizer(mPlayer.getAudioSessionId());
//vis.setDataCaptureListener(this, 20, true, true);
}
catch(Exception ex){ Log.w("ExCePtIoN", ex+""); }
mPlayer.start();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_fft, menu);
return true;
}
}
最后一个问题是当我执行mPlayer.prepare()方法时,它会抛出IllegalStateException。
以下是完整的LogCat消息:
07-06 18:33:17.141: E/Trace(833): error opening trace file: No such file or directory (2)
07-06 18:33:17.591: E/MediaPlayer(833): prepareAsync called in state 8
07-06 18:33:17.591: W/ExCePtIoN(833): java.lang.IllegalStateException
07-06 18:33:17.621: E/AudioEffect(833): set(): AudioFlinger could not create effect, status: -22
07-06 18:33:17.621: E/visualizers-JNI(833): Visualizer initCheck failed -4
07-06 18:33:17.621: E/Visualizer-JAVA(833): Error code -4 when initializing Visualizer.
07-06 18:33:17.621: W/ExCePtIoN(833): java.lang.RuntimeException: Cannot initialize Visualizer engine, error: -4
07-06 18:33:18.482: I/Choreographer(833): Skipped 337 frames! The application may be doing too much work on its main thread.
07-06 18:33:18.551: D/gralloc_goldfish(833): Emulator without GPU emulation detected.