我一直在开发一个简单的 Android 应用程序,旨在将流式相机帧从 Android Camera2 API 管道传递到我的算法。我已经制作了几个应用程序,忠实地使用 Android Camera1 API 执行此操作,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 捕获任何真实数据。请注意以下相关代码:
-
设置图像读取器:
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....]
}
-
设置捕获会话:
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 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...]
}
};
在代码片段 #3 中,无论 ImageReader 格式如何,我的字节缓冲区始终返回空(全零)。有人遇到过这个问题吗?我是否缺少任何代码?
add 缓冲区.get(字节);后byte[] bytes = new byte[buffer.remaining()];
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