将Android摄像头的视频保存为本地.mjpeg文件

Question

我正在研究将视频保存为Android设备上的.mpeg文件的应用程序。我一直在Github上与vanevery的MJPEG项目合作，只取得了一些成功，（https://github.com/vanevery/Android-MJPEG-Video-Capture-FFMPEG/blob/master/src/com/mobvcasting/mjpegffmpeg/MJPEGFFMPEGTest.java）。

这是到目前为止我的代码：

public class VideoCapture extends Activity implements OnClickListener, SurfaceHolder.Callback, Camera.PreviewCallback { 
public static final String LOGTAG = "VIDEOCAPTURE"; 
String szBoundaryStart = "\r\n\r\n--myboundary\r\nContent-Type: image/jpeg\r\nContent-Length: "; 
String szBoundaryDeltaTime = "\r\nDelta-time: 110"; 
String szBoundaryEnd = "\r\n\r\n"; 
private SurfaceHolder holder; 
private Camera camera; 
private CamcorderProfile camcorderProfile; 
boolean bRecording = false; 
boolean bPreviewRunning = false; 
byte[] previewCallbackBuffer; 
File mjpegFile; 
FileOutputStream fos; 
BufferedOutputStream bos; 
Button btnRecord; 
Camera.Parameters p; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    Date T = new Date(); 
    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss"); 
    String szFileName = "videocapture-"+sdf.format(T)+"-";  
    try {  
     mjpegFile = File.createTempFile(szFileName, ".mjpeg", Environment.getExternalStorageDirectory());    
    } catch (Exception e) { 
     Log.v(LOGTAG,e.getMessage()); 
     finish(); 
    } 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
      WindowManager.LayoutParams.FLAG_FULLSCREEN); 
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); 
    setContentView(R.layout.main); 
    btnRecord = (Button) this.findViewById(R.id.RecordButton); 
    btnRecord.setOnClickListener(this); 
    camcorderProfile = CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH); 
    SurfaceView cameraView = (SurfaceView) findViewById(R.id.CameraView); 
    holder = cameraView.getHolder(); 
    holder.addCallback(this); 
    holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
    cameraView.setClickable(true); 
    cameraView.setOnClickListener(this); 
} 
public void onClick(View v) { 
    if (bRecording) { 
     bRecording = false; 
     try { 
      bos.flush(); 
      bos.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     Log.v(LOGTAG, "Recording Stopped"); 
    } else { 
     try { 
      fos = new FileOutputStream(mjpegFile); 
      bos = new BufferedOutputStream(fos); 
      bRecording = true; 
      Log.v(LOGTAG, "Recording Started"); 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } 
    } 
} 
public void surfaceCreated(SurfaceHolder holder) { 
    Log.v(LOGTAG, "surfaceCreated");   
    camera = Camera.open();  
} 
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { 
    Log.v(LOGTAG, "surfaceChanged"); 
    if (!bRecording) { 
     if (bPreviewRunning){ 
      camera.stopPreview(); 
     } try { 
      p = camera.getParameters(); 
      p.setPreviewSize(camcorderProfile.videoFrameWidth, camcorderProfile.videoFrameHeight); 
      p.setPreviewFrameRate(camcorderProfile.videoFrameRate); 
      camera.setParameters(p); 
      camera.setPreviewDisplay(holder); 
      camera.setPreviewCallback(this); 
      Log.v(LOGTAG,"startPreview"); 
      camera.startPreview(); 
      bPreviewRunning = true; 
     } catch (IOException e) { 
      Log.e(LOGTAG,e.getMessage()); 
      e.printStackTrace(); 
     } 
    } 
} 
public void surfaceDestroyed(SurfaceHolder holder) { 
    Log.v(LOGTAG, "surfaceDestroyed"); 
    if (bRecording) { 
     bRecording = false; 
     try { 
      bos.flush(); 
      bos.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
    bPreviewRunning = false; 
    camera.release(); 
    finish(); 
} 
public void onPreviewFrame(byte[] b, Camera c) { 
    if (bRecording) { 
     // Assuming ImageFormat.NV21 
     if (p.getPreviewFormat() == ImageFormat.NV21) { 
      Log.v(LOGTAG,"Started Writing Frame"); 
      try { 
       ByteArrayOutputStream jpegByteArrayOutputStream = new ByteArrayOutputStream(); 
       YuvImage im = new YuvImage(b, ImageFormat.NV21, p.getPreviewSize().width, p.getPreviewSize().height, null); 
       Rect r = new Rect(0,0,p.getPreviewSize().width,p.getPreviewSize().height); 
       im.compressToJpeg(r, 5, jpegByteArrayOutputStream);       
       byte[] jpegByteArray = jpegByteArrayOutputStream.toByteArray(); 
       byte[] boundaryBytes = (szBoundaryStart + jpegByteArray.length + szBoundaryDeltaTime + szBoundaryEnd).getBytes(); 
       bos.write(boundaryBytes); 
       bos.write(jpegByteArray); 
       bos.flush(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
      Log.v(LOGTAG,"Finished Writing Frame"); 
     } else { 
      Log.v(LOGTAG,"NOT THE RIGHT FORMAT"); 
     } 
    } 
} 
@Override 
public void onConfigurationChanged(Configuration conf) 
{ 
    super.onConfigurationChanged(conf); 
} 
} 

我怀疑问题可能出在onPreviewFrame的JPEG格式（解析）（）。任何帮助或建议将不胜感激。提前致谢。

Answer 1

看起来有一个关于MJPEG文件播放所需的JPEG质量的阈值。更改，

im.compressToJpeg(r, 5, jpegByteArrayOutputStream); 

到，

im.compressToJpeg(r, 75, jpegByteArrayOutputStream); 

导致有效的MJPEG文件。