捕捉Camera2预览帧返回空缓冲区

Question

我一直在研究一个简单的Android应用程序，旨在将来自Android Camera2 API管道的流式摄像头帧传递给我的算法。我已经使用Android Camera1 API忠实地完成了多个应用程序，但即使在检查（Google文档，论坛）以确认正确的编码之后，我也无法从onImageAvailable（）中的ImageReader捕获任何实际数据。请注意以下相关的代码：

1. 设置所述的ImageReaders：

   private void setUpCameraOutputs(int width, int height) { 
   
   [....code....] 
   
   mImageReader = ImageReader.newInstance(smallestJPEG.getWidth(), 
                smallestJPEG.getHeight(), 
                ImageFormat.JPEG, /*maxImages*/2); 
   // mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, null); 
   mPreviewImageReader = ImageReader.newInstance(smallest.getWidth(), 
                  smallest.getHeight(), 
                  ImageFormat.YUV_420_888, 2); 
   mPreviewImageReader.setOnImageAvailableListener(mOnPreviewImageAvailableListener, 
                  mBackgroundHandler); 
   
   [....code....] 
   
   } 
   

设置的CaptureSession：

private void createCameraPreviewSession() { 
try { 
    //Create Texture from Screen's TextureView 
    SurfaceTexture texture = mTextureView.getSurfaceTexture(); 

    assert texture != null; 

    //Configure Default Buffer Size 
    texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight()); 

    //Create Output Surface from Texture 
    Surface surface = new Surface(texture); 

    // Set up a CaptureRequest.Builder with the output Surface. 
    mPreviewRequestBuilder 
      = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); 

    //Add Output Display surface 
    mPreviewRequestBuilder.addTarget(surface); 

    //Add Preview frame-grabbing surface 
    mPreviewRequestBuilder.addTarget(mPreviewImageReader.getSurface()); 

    mCameraDevice.createCaptureSession(Arrays.asList(surface, mPreviewImageReader.getSurface()), 
      new CameraCaptureSession.StateCallback() { 

       @Override 
       public void onConfigured(CameraCaptureSession cameraCaptureSession) { 
        // The camera is already closed 
        if (null == mCameraDevice) { 
         return; 
        } 

        // When the session is ready, we start displaying the preview. 
        mCaptureSession = cameraCaptureSession; 
        try { 
         // Auto focus should be continuous for camera preview. [...code...] 
         mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, 
           CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); 
         // Flash is automatically enabled when necessary. 
         mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, 
           CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); 

         // Finally, we start displaying the camera preview. 
         mPreviewRequest = mPreviewRequestBuilder.build(); 
         mCaptureSession.setRepeatingRequest(mPreviewRequest, 
           mCaptureCallback, mBackgroundHandler); 
        } catch (CameraAccessException e) { 
         [...code...] 
        } 
       } 

       @Override 
       public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) { 
        [...code...] 
       } 
      }, null 
    ); 
} catch (CameraAccessException e) { 
    [...code...] 
} 
} 

设置的OnImageAvailableListener：

private ImageReader mPreviewImageReader; 
private final ImageReader.OnImageAvailableListener mOnPreviewImageAvailableListener 
= new ImageReader.OnImageAvailableListener() { 

@Override 
public void onImageAvailable(ImageReader reader) { 

    //Acquire Image, ByteBuffer, then byte array 
    Image image = reader.acquireLatestImage(); 
    ByteBuffer buffer = image.getPlanes()[0].getBuffer(); 
    byte[] bytes = new byte[buffer.remaining()]; 

    //Check bytes array for anydata 
    int cnt = 0; 
    for (int i = 0; i < bytes.length; i++){ 
     if (bytes[i] != 0)cnt++; 
    } 
    Log.i(TAG, "cnt = " + cnt); 
    image.close(); 

    //At this point, byte[] bytes is empty (all zero) 
    [...code...] 
} 

}; 

在代码段＃3，我的字节缓冲器总是返回空（全0），而不管ImageReader格式。有没有人有这个问题？我是否缺少任何代码？

Answer 1

add buffer.get（bytes）;byte [] bytes = new byte [buffer.remaining（）];