Add video capture feature to CIVideoDemoGL

Question

Hello,
I'm a little bit stuck with the CIVideoDemoGL. How do I add video capture feature to this demo instead of using a file as input?
I know how I capture the video stream from camera and captureOutput:didOutputVideoFrame:withSampleBuffer:fromConnection: is called every time a new frame comes. I can also see a preview of the captured video on screen on the CaptureView.
What I want to accomplish is methods to manipulate video on the fly (as in CIVideoDemoGL) directly from a camera (iSight or likely).
I have tried to change renderCurrentFrame in VideoView.m. Instead of
+inputImage = [CIImage imageWithCVImageBuffer:currentFrame];+ I have made a method that retrieve a CIImage* from VideoController (where I've place every captured frame from camera).
The method call is like this: +[delegate getCurrentCapturedFrame:self data:(CIImage*)inputImage];+
This method initializes the given CIImage with data from the captured frame.
When I run this code I retrieve the following error in console +Program received signal: “EXCBADACCESS”.+
So, something bad is going on but I don't know if I'm on the right way. Maybe it's my method getCurrentCapturedFrame that returns a bad object.
Any ideas?

Answer 1

Hello again,
Thanks for your help. There was something wrong with my code.
During this weekend I have managed to get captured video playing. But the video is almost black and white and if you zoom into it you can see red blue and green vertical lines. Even if I remove the filters I can see this happen. If I compare the video with the Capture view that I have implemented beside the OpenGL View I can see all colors on the first one. Any ideas?
I have modified the original renderCurrentFrame to the following:
- (void)renderCurrentFrame
NSRect frame = [self frame];
NSRect bounds = [self bounds];
CGRect imageRect;
CIImage *inputImage;
CIImage *timecodeImage;
// update timecode overlay
timecodeImage = [timeCodeOverlay getImageForTime:[self currentTime]];
if(!readyToGrabFrame)
return;
//Put captured image into inputImage
inputImage = [CIImage imageWithCVImageBuffer:mCurrentImageBuffer];
imageRect = [inputImage extent];
[colorCorrectionFilter setValue:inputImage forKey:@"inputImage"];
[effectFilter setValue:[colorCorrectionFilter valueForKey:@"outputImage"] forKey:@"inputImage"];
[compositeFilter setValue:[effectFilter valueForKey:@"outputImage"] forKey:@"inputBackgroundImage"];
[compositeFilter setValue:timecodeImage forKey:@"inputImage"];
CGPoint p = CGPointMake((int)((frame.size.width - imageRect.size.width) * 0.5), (int)((frame.size.height - imageRect.size.height) * 0.5));
// render our resulting image into our context
[ciContext drawImage:[compositeFilter valueForKey:@"outputImage"]
atPoint:p
fromRect:imageRect];
// housekeeping on the visual context
QTVisualContextTask(qtVisualContext);
My captureOutput:didOutputVideoFrame:withSampleBuffer:fromConnection is moved to VideoView class instead and I have also created an object that keeps the captured buffer with the name mCurrentImageBuffer
The method looks like this now:
- (void)captureOutput:(QTCaptureOutput *)captureOutput didOutputVideoFrame:(CVImageBufferRef)videoFrame withSampleBuffer:(QTSampleBuffer *)sampleBuffer fromConnection:(QTCaptureConnection *)connection
countFrames++;
[lock lock];
CVImageBufferRef releasedImageBuffer;
CVBufferRetain(videoFrame);
@synchronized(self)
//basically, have frame to be released refer to the current frame
//then update the reference to the current frame with the next frame in the "video stream"
releasedImageBuffer = mCurrentImageBuffer;
mCurrentImageBuffer = videoFrame;
CVBufferRelease(releasedImageBuffer);
readyToGrabFrame = YES;
[lock unlock];