I am using AVFoundation and getting the sample buffer from AVCaptureVideoDataOutput
, I can write it directly to videoWriter by using:
- (void)writeBufferFrame:(CMSampleBufferRef)sampleBuffer {
CMTime lastSampleTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
if(self.videoWriter.status != AVAssetWriterStatusWriting)
{
[self.videoWriter startWriting];
[self.videoWriter startSessionAtSourceTime:lastSampleTime];
}
[self.videoWriterInput appendSampleBuffer:sampleBuffer];
}
What I want to do now is to crop and scale the image inside the CMSampleBufferRef without converting it into UIImage or CGImageRef because that slows down the performance.
If you use vimage you can work directly on the buffer data without converting it to any image format.
outImg
contains the cropped and scaled image data. The relation betweenoutWidth
andcropWidth
sets the scaling.So setting
cropX0 = 0
andcropY0 = 0
andcropWidth
andcropHeight
to the original size means no cropping (using the whole original image). SettingoutWidth = cropWidth
andoutHeight = cropHeight
results in no scaling. Note thatinBuff.rowBytes
should always be the length of the full source buffer, not the cropped length.