这是我用来以MP4格式从Android设备录制视频的代码。正在创建文件，但大小为0字节。我似乎不明白出了什么问题。任何帮助将不胜感激。
if(mCamera == null) {
mCamera = Camera.open();
mCamera.unlock();
}
if(mediaRecorder == null)
mediaRecorder = new MediaRecorder();
mediaRecorder.setCamera(mCamera);
mediaRecorder.setCamera(mCamera);
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
mediaRecorder.setMaxDuration(maxDurationInMs);
mediaRecorder.setOutputFile("/sdcard/1.mp4");
mediaRecorder.setVideoFrameRate(videoFramesPerSecond);
mediaRecorder.setVideoSize(176,144);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.DEFAULT);
mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
mediaRecorder.setPreviewDisplay(surface);
mediaRecorder.setMaxFileSize(maxFileSizeInBytes);
mediaRecorder.prepare();
try {
mediaRecorder.prepare();
} catch (IllegalStateException e) {
// This is thrown if the previous calls are not called with the
// proper order
e.printStackTrace();
}
mediaRecorder.start();
答案 0 :(得分：9)
这种行为的原因是你很可能（95％肯定）在你完成录音后再次再次呼叫recorder.setOutputFile()（也许在recorder.stop()之后）。因此旧文件正被新的空文件重写。
答案 1 :(得分：4)
http://developer.android.com/guide/topics/media/camera.html#saving-media
答案 2 :(得分：2)
以下代码对我有用：
private boolean isRecording = false;
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_video_record);
// Create an instance of Camera
mCamera = getCameraInstance();
mHolder = surfaceViewRecReadyTestimonial.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
} catch (Exception e) {
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
private boolean prepareVideoRecorder() {
mCamera = getCameraInstance();
mMediaRecorder = new MediaRecorder();
// Step 1: Unlock and set camera to MediaRecorder
mCamera.unlock();
mMediaRecorder.setCamera(mCamera);
// Step 2: Set sources
mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
// Step 3: Set a CamcorderProfile (requires API Level 8 or higher)
mMediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH));
// Step 4: Set output file
mMediaRecorder.setOutputFile(getOutputMediaFile(MEDIA_TYPE_VIDEO).toString());
// Step 5: Set the preview output
mMediaRecorder.setPreviewDisplay(surfaceViewRecReadyTestimonial.getHolder().getSurface());
// Step 6: Prepare configured MediaRecorder
try {
mMediaRecorder.prepare();
} catch (IllegalStateException e) {
Log.d(TAG, "IllegalStateException preparing MediaRecorder: " + e.getMessage());
releaseMediaRecorder();
return false;
} catch (IOException e) {
Log.d(TAG, "IOException preparing MediaRecorder: " + e.getMessage());
releaseMediaRecorder();
return false;
}
return true;
}
@Override
public void onClick(View v) {
if (v == btnStart) {
// initialize video camera
if (prepareVideoRecorder()) {
// Camera is available and unlocked, MediaRecorder is prepared,
// now you can start recording
mMediaRecorder.start();
// inform the user that recording has started
isRecording = true;
} else {
// prepare didn't work, release the camera
releaseMediaRecorder();
// inform user
}
} else if (v == btnStop) {
if (isRecording) {
// stop recording and release camera
mMediaRecorder.stop(); // stop the recording
releaseMediaRecorder(); // release the MediaRecorder object
mCamera.lock(); // take camera access back from MediaRecorder
// inform the user that recording has stopped
isRecording = false;
}
} }
private void releaseMediaRecorder() {
if (mMediaRecorder != null) {
mMediaRecorder.reset(); // clear recorder configuration
mMediaRecorder.release(); // release the recorder object
mMediaRecorder = null;
mCamera.lock(); // lock camera for later use
}
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
/**
* Create a File for saving an image or video
*/
private static File getOutputMediaFile(int type) {
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DCIM), "FolderName");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d("FolderName", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_" + timeStamp + ".jpg");
} else if (type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_" + timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
@Override
protected void onPause() {
super.onPause();
releaseMediaRecorder(); // if you are using MediaRecorder, release it first
releaseCamera(); // release the camera immediately on pause event
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d("RecordVideo", "Error setting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null) {
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e) {
// ignore: tried to stop a non-existent preview
}
try {
Camera.Parameters parameters = mCamera.getParameters();
Display display = ((WindowManager) getSystemService(WINDOW_SERVICE)).getDefaultDisplay();
if (display.getRotation() == Surface.ROTATION_0) {
parameters.setPreviewSize(height, width);
mCamera.setDisplayOrientation(90);
}
if (display.getRotation() == Surface.ROTATION_90) {
parameters.setPreviewSize(width, height);
}
if (display.getRotation() == Surface.ROTATION_180) {
parameters.setPreviewSize(height, width);
}
if (display.getRotation() == Surface.ROTATION_270) {
parameters.setPreviewSize(width, height);
mCamera.setDisplayOrientation(180);
}
if (mCamera != null) {
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (Exception e) {
e.printStackTrace();
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e) {
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
答案 3 :(得分：0)
public static final String rootDir = getStorageDir().concat(yours_dir); ... mediaRecorder.setOutputFile(rootDir);
答案 4 :(得分：0)
您是否设置了用户权限
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />