我需要从相机对象中获取原始预览数据，至少每秒15帧，但我只能在110毫秒内获取一帧，这意味着我只能获得每秒9帧。以下是我的代码简介。
在上述简要代码中，dataBufferSize和videoCaptureViewHolder被定义并在其他语句中计算或赋值。
我运行我的代码，可以在屏幕上看到预览，并获得以下日志：
这意味着每110毫秒就会调用 onPreviewFrame(byte[] data, Camera camera) 方法，因此我最多只能获得9帧每秒的预览。无论我通过 setPreviewFrameRate() 和 setPreviewFpsRange() 设置什么样的预览帧率和预览FPS范围，日志都是相同的。
Camera mCamera = Camera.open();
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewFrameRate(30);
parameters.setPreviewFpsRange(15000,30000);
mCamera.setParameters(parameters);
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
//dataBufferSize stands for the byte size for a picture frame
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
mCamera.setPreviewDisplay(videoCaptureViewHolder);
//videoCaptureViewHolder is a SurfaceHolder object
mCamera.setPreviewCallbackWithBuffer(new Camera.PreviewCallback() {
private long timestamp=0;
public synchronized void onPreviewFrame(byte[] data, Camera camera) {
Log.v("CameraTest","Time Gap = "+(System.currentTimeMillis()-timestamp));
timestamp=System.currentTimeMillis();
//do picture data process
camera.addCallbackBuffer(data);
return;
}
}
mCamera.startPreview();
在上述简要代码中，dataBufferSize和videoCaptureViewHolder被定义并在其他语句中计算或赋值。
我运行我的代码，可以在屏幕上看到预览，并获得以下日志：
...
V/CameraTest( 5396): Time Gap = 105
V/CameraTest( 5396): Time Gap = 112
V/CameraTest( 5396): Time Gap = 113
V/CameraTest( 5396): Time Gap = 115
V/CameraTest( 5396): Time Gap = 116
V/CameraTest( 5396): Time Gap = 113
V/CameraTest( 5396): Time Gap = 115
...
这意味着每110毫秒就会调用 onPreviewFrame(byte[] data, Camera camera) 方法，因此我最多只能获得9帧每秒的预览。无论我通过 setPreviewFrameRate() 和 setPreviewFpsRange() 设置什么样的预览帧率和预览FPS范围，日志都是相同的。
有人能帮我解决这个问题吗？我需要至少15帧每秒的Camera对象原始预览数据。谢谢。
我将我的整个代码放在下面。
CameraTest.java
package test.cameratest;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import android.app.Activity;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.hardware.Camera.ErrorCallback;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class CameraTestActivity extends Activity {
SurfaceView mVideoCaptureView;
Camera mCamera;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mVideoCaptureView = (SurfaceView) findViewById(R.id.video_capture_surface);
SurfaceHolder videoCaptureViewHolder = mVideoCaptureView.getHolder();
videoCaptureViewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
videoCaptureViewHolder.addCallback(new Callback() {
public void surfaceDestroyed(SurfaceHolder holder) {
}
public void surfaceCreated(SurfaceHolder holder) {
startVideo();
}
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
}
private void startVideo() {
SurfaceHolder videoCaptureViewHolder = null;
try {
mCamera = Camera.open();
} catch (RuntimeException e) {
Log.e("CameraTest", "Camera Open filed");
return;
}
mCamera.setErrorCallback(new ErrorCallback() {
public void onError(int error, Camera camera) {
}
});
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewFrameRate(30);
parameters.setPreviewFpsRange(15000,30000);
List<int[]> supportedPreviewFps=parameters.getSupportedPreviewFpsRange();
Iterator<int[]> supportedPreviewFpsIterator=supportedPreviewFps.iterator();
while(supportedPreviewFpsIterator.hasNext()){
int[] tmpRate=supportedPreviewFpsIterator.next();
StringBuffer sb=new StringBuffer();
sb.append("supportedPreviewRate: ");
for(int i=tmpRate.length,j=0;j<i;j++){
sb.append(tmpRate[j]+", ");
}
Log.v("CameraTest",sb.toString());
}
List<Size> supportedPreviewSizes=parameters.getSupportedPreviewSizes();
Iterator<Size> supportedPreviewSizesIterator=supportedPreviewSizes.iterator();
while(supportedPreviewSizesIterator.hasNext()){
Size tmpSize=supportedPreviewSizesIterator.next();
Log.v("CameraTest","supportedPreviewSize.width = "+tmpSize.width+"supportedPreviewSize.height = "+tmpSize.height);
}
mCamera.setParameters(parameters);
if (null != mVideoCaptureView)
videoCaptureViewHolder = mVideoCaptureView.getHolder();
try {
mCamera.setPreviewDisplay(videoCaptureViewHolder);
} catch (Throwable t) {
}
Log.v("CameraTest","Camera PreviewFrameRate = "+mCamera.getParameters().getPreviewFrameRate());
Size previewSize=mCamera.getParameters().getPreviewSize();
int dataBufferSize=(int)(previewSize.height*previewSize.width*
(ImageFormat.getBitsPerPixel(mCamera.getParameters().getPreviewFormat())/8.0));
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
mCamera.addCallbackBuffer(new byte[dataBufferSize]);
mCamera.setPreviewCallbackWithBuffer(new Camera.PreviewCallback() {
private long timestamp=0;
public synchronized void onPreviewFrame(byte[] data, Camera camera) {
Log.v("CameraTest","Time Gap = "+(System.currentTimeMillis()-timestamp));
timestamp=System.currentTimeMillis();
try{
camera.addCallbackBuffer(data);
}catch (Exception e) {
Log.e("CameraTest", "addCallbackBuffer error");
return;
}
return;
}
});
try {
mCamera.startPreview();
} catch (Throwable e) {
mCamera.release();
mCamera = null;
return;
}
}
private void stopVideo() {
if(null==mCamera)
return;
try {
mCamera.stopPreview();
mCamera.setPreviewDisplay(null);
mCamera.setPreviewCallbackWithBuffer(null);
mCamera.release();
} catch (IOException e) {
e.printStackTrace();
return;
}
mCamera = null;
}
public void finish(){
stopVideo();
super.finish();
};
}
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="test.cameratest"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="9" android:targetSdkVersion="10" android:maxSdkVersion="10"/>
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.READ_CONTACTS"/>
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS"/>
<uses-permission android:name="android.permission.CALL_PHONE"/>
<uses-permission android:name="android.permission.BOOT_COMPLETED"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".CameraTestActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Camera.Parameters.setPreviewFrameRate()和Camera.Parameters.setPreviewFpsRange()中使用不支持的值比根本不调用这些方法更糟糕。因此，首先获取支持的FPS（或范围）列表，并选择最好的一个，而不是像上面的示例中那样硬编码为30。 - Alex Cohn