我正在使用 Android camera2 以在预览模式下实时提取帧以将它们缝合到 NDK 端(openCv)。我使用ImageReader
表面来获取帧,但它仅限于最大帧值。
ImageReader.newInstance(800,600,ImageFormat.YUV_420_888, MAX_FRAME);
它工作得很好,但由于我们需要所有帧,因此必须从ImageReader
目标表面移除CaptureRequest.Builder
并再次添加它。所以我们在这一点上有一个滞后。
我们怎样才能ImageReader
没有最大帧,或者我们怎样才能从camera2中的实时视频中获取所有帧而没有任何预览延迟?
我的代码:
private void startPreview() {
if (null == mCameraDevice || !mTextureView.isAvailable() || null == mPreviewSize) {
return;
}
try {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface previewSurface = new Surface(texture);
surfaces = new ArrayList<>();
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
surfaces.add(previewSurface);
mPreviewBuilder.addTarget(previewSurface);
mPreviewCaptureCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
// closePreviewSession();
mPreviewSession = session;
try {
session.setRepeatingRequest(mPreviewBuilder.build(), null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
Activity activity = getActivity();
if (null != activity) {
Toast.makeText(activity, "Failed", Toast.LENGTH_SHORT).show();
}
}
};
mCameraDevice.createCaptureSession(surfaces, mPreviewCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void addImageReaderSurface() {
try {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface previewSurface = new Surface(texture);
surfaces = new ArrayList<>();
mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
surfaces.add(previewSurface);
mPreviewBuilder.addTarget(previewSurface);
newImageReader(10);
surfaces.add(mImageReader.getSurface());
mPreviewBuilder.addTarget(mImageReader.getSurface());
mPreviewCaptureCallback = new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
mPreviewSession = session;
try {
mPreviewSession.setRepeatingRequest(mPreviewBuilder.build(), null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
Activity activity = getActivity();
if (null != activity) {
Toast.makeText(activity, "Failed", Toast.LENGTH_SHORT).show();
}
}
};
mCameraDevice.createCaptureSession(surfaces, mPreviewCaptureCallback, mBackgroundHandler);
} catch (Exception e) {
e.printStackTrace();
}
}
private void newImageReader(final int count) {
mImageReader = ImageReader.newInstance(800, 600, ImageFormat.YUV_420_888, count);
mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
index++;
Log.e("xxx", "frame " + index + " received");
if (index == count) {
index = 0;
// remove it before reached max value
addImageReaderSurface();
}
}
}, mBackgroundHandler);
}