java - MediaRecorder 不保存文件

Question

我查看了其他人遇到的这个问题，但没有找到合适的解决方案。像他们一样，我遵循了相机功能教程:http://developer.android.com/guide/topics/media/camera.html .下面列出的所有内容都非常完美，以至于我认为该程序已按照我的预期录制了视频。然而，在查看画廊中的视频时，它并没有出现。我很困惑，因为在连接 USB 调试时没有出现 IOExceptions 或其他错误。奇怪的是，在移除 USB 并再次插入时，无论是立即还是在未来几天的某个时候，所有以前录制的视频都会出现在图库中。显然我遗漏了一些东西，或者我不知道录制视频的某些方面。非常感谢任何帮助或指导，谢谢。

相关代码如下，有需要的我再贴上。

相机 Activity :

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_camera);

    mCamera = MainActivity.getCameraInstance();
    // Create our Preview view and set it as the content of our activity.
    mPreview = new CameraPreview(this, mCamera);
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
    preview.addView(mPreview);
    button_capture = (Button) findViewById(R.id.button_capture);
    button_capture.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    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
                        button_capture.setText("Capture");
                        isRecording = false;
                    } else {
                        // 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
                            button_capture.setText("Stop");
                            isRecording = true;
                        } else {
                            // prepare didn't work, release the camera
                            releaseMediaRecorder();
                            // inform user
                        }
                    }
                }
            });
}

private boolean prepareVideoRecorder(){

    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(MediaCapture.getOutputMediaFile(MEDIA_TYPE_VIDEO).toString());

    // Step 5: Set the preview output
    mMediaRecorder.setPreviewDisplay(mPreview.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;
}

媒体捕捉:

public static Uri getOutputMediaFileUri(int type) {
    return Uri.fromFile(getOutputMediaFile(MEDIA_TYPE_VIDEO));
}

/**
 * Create a File for saving an image or video
 */
public 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_MOVIES), "MyApplication");

    // 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("MyApplication", "failed to create directory");
            return null;
        }
    }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HH:mm:ss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_VIDEO) {
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                    "VID_" + timeStamp + ".mp4");
        } else {
            return null;
        }
        return mediaFile;
    }
}

Answer 1

我也对这种行为感到非常困惑，直到我意识到拔下 USB 导致文件出现。这似乎是 Android 中的一个错误，可能与此有关:

https://code.google.com/p/android/issues/detail?id=195362

很明显，文件已经正确写入，但由于某些原因，新文件不可见。无论如何，上面链接中提供的解决方案/解决方法是强制对您的文件进行媒体扫描。例如

MediaScannerConnection.scanFile(getContext(), new String[]{this.mediaFile.getAbsolutePath()}, null, null);

“mediaFile”是您的 mediaRecorder 刚刚完成写入的文件。有了这个，我不需要拔下 USB 电缆来查看文件，它会在录制完成后立即出现。

我在三星 Galaxy A5 上运行 Android 5.0.2。这感觉更像是一种解决方法而不是修复，我不能确定它是否适用于其他设备或 Android 版本，但我希望它对某人有所帮助。