onPreviewframe tylko wywoływana raz

Question

pracuję w aplikacji aparatu, y trzeba wyodrębnić pewne dane podglądu każda ramka więc y próbował zrobić to za pomocą onPreviewFrame, problemem jest to, że z mojego kodu onPreviewFrame jest wywoływana tylko raz podczas debugowania I nie będziesz błędów więc nie wiem, co robić

tutaj jest mój kod

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback { 
    private static final String TAG = "CameraPreview"; 
    private SurfaceHolder mHolder; 
    private Camera mCamera; 
    public byte[] buffer;//for previewcallback 

    public CameraPreview(Context context, Camera camera) { 
     super(context); 
     Log.d("Function", "CameraPreview constructor iniciado"); 
     mCamera = camera; 

     // Install a SurfaceHolder.Callback so we get notified when the 
     // underlying surface is created and destroyed. 
     mHolder = getHolder(); 
     mHolder.addCallback(this); 
     // deprecated setting, but required on Android versions prior to 3.0 
     mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
    } 

    public void surfaceCreated(SurfaceHolder holder) { 
     // The Surface has been created, now tell the camera where to draw the preview. 
     Log.d("Function", "SurfaceCreated iniciado"); 
     try { 
      mCamera.setPreviewDisplay(holder); 

      buffer = previewBuffer(); 
      mCamera.addCallbackBuffer(buffer); 
      mCamera.setPreviewCallbackWithBuffer(previewCallback); 

      mCamera.startPreview(); 

     } catch (IOException e) { 
      Log.d(TAG, "Error setting camera preview: " + e.getMessage()); 
     } 
    } 

    public void surfaceDestroyed(SurfaceHolder holder) { 
     // Surface will be destroyed when we return, so stop the preview. 
     Log.d("Function", "SurfaceDestroyed iniciado"); 

    } 

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { 
     // If your preview can change or rotate, take care of those events here. 
     // Make sure to stop the preview before resizing or reformatting it. 
     Log.d("Function", "surfaceChanged iniciado"); 
     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 
     } 

     // set preview size and make any resize, rotate or 
     // reformatting changes here 


     // start preview with new settings 
     try { 
      mCamera.setPreviewDisplay(mHolder); 

      buffer = previewBuffer(); 
      mCamera.addCallbackBuffer(buffer); 
      mCamera.setPreviewCallbackWithBuffer(previewCallback); 

      mCamera.startPreview(); 

     } catch (Exception e) { 
      Log.d(TAG, "Error starting camera preview: " + e.getMessage()); 
     } 
    } 

    //Create the callback to access preview frames 
    PreviewCallback previewCallback = new PreviewCallback() { 

     public void onPreviewFrame(byte[] data, Camera camera) { 
      // TODO Auto-generated method stub 
      Log.d("Function", "onPreviewFrame iniciado"); 
      //Convert to jpg 
      Size previewSize = camera.getParameters().getPreviewSize(); 
      Log.d("Function", "onPreviewFrame: preview size=" + previewSize.height + " " + previewSize.width); 
      YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21, previewSize.width, previewSize.height, null); 
      ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
      yuvImage.compressToJpeg(new Rect(0, 0, previewSize.width, previewSize.height), 80, baos); 
      byte jpgData[] = baos.toByteArray(); 
     } 
    }; 

    //To create a buffer of the preview bytes size 
    private byte[] previewBuffer() { 
     Log.d("Function", "previewBuffer iniciado"); 
     int bufferSize; 
     byte buffer[]; 
     int bitsPerPixel; 

     Camera.Parameters mParams = mCamera.getParameters(); 
     Camera.Size mSize = mParams.getPreviewSize(); 
     Log.d("Function", "previewBuffer: preview size=" + mSize.height + " " + mSize.width); 
     int mImageFormat = mParams.getPreviewFormat(); 

     if (mImageFormat == ImageFormat.YV12) { 
      int yStride = (int) Math.ceil(mSize.width/16.0) * 16; 
      int uvStride = (int) Math.ceil((yStride/2)/16.0) * 16; 
      int ySize = yStride * mSize.height; 
      int uvSize = uvStride * mSize.height/2; 
      bufferSize = ySize + uvSize * 2; 
      buffer = new byte[bufferSize]; 
      Log.d("Function", "previewBuffer: buffer size=" + Integer.toString(bufferSize)); 
      return buffer; 
     } 

     bitsPerPixel = ImageFormat.getBitsPerPixel(mImageFormat); 
     bufferSize = (int) (mSize.height * mSize.width * ((bitsPerPixel/(float) 8))); 
     buffer = new byte[bufferSize]; 
     Log.d("Function", "previewBuffer: buffer size=" + Integer.toString(bufferSize)); 
     return buffer; 
    } 
} 

Answer 1

po otrzymaniu bufor podglądu dodany z addCallbackBuffer, trzeba go oddać do kamery gdy skończysz (w przeciwnym razie kamera może nadpisać twoje dane przed ich użyciem). Kiedy skończysz używać tablicy bajtów danych w wywołaniu onPreviewFrame, oddaj ją ponownie do aparatu z addCallbackBuffer.

Można także rozważyć dodanie dwóch lub więcej buforów zwrotnych po skonfigurowaniu aparatu. Kamera po prostu upuszcza klatki, jeśli nie ma wolnego bufora do użycia, więc posiadanie kilku wolnych buforów może wygładzić liczbę klatek na sekundę, jeśli masz sporadyczne usterki lub inne opóźnienia w przetwarzaniu.