Applying CIFilter to video in iOS

Question

I'm working on a video conferencing app, and the following code draws a frame to the screen succesfully:

 -(int)drawFrameOnMainThread{
    if(mBitmapContext){
        if(mDisplay){
            CGImageRef imageRef = CGBitmapContextCreateImage(mBitmapContext);
    #if TARGET_OS_IPHONE
            UIImage *image = [UIImage imageWithCGImage:imageRef];

            [self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES];

    #elif TARGET_OS_MAC
            [mDisplay setCurrentImage:imageRef];
    #endif
            CGImageRelease(imageRef);
        }
    }
    return 0;
}

I want to apply a CIFilter to the frame being drawn, so I modify the iOS section of the code like so:

UIImage *image = [UIImage imageWithCGImage:imageRef];

        CIImage *beginImage = image.CIImage;

        CIContext *context = [CIContext contextWithOptions:nil];

        CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone" 
                                      keysAndValues: kCIInputImageKey, beginImage, 
                            @"inputIntensity", [NSNumber numberWithFloat:0.8], nil];
        CIImage *outputImage = [filter outputImage];

        CGImageRef cgimg = 
        [context createCGImage:outputImage fromRect:[outputImage extent]];
        UIImage *newImg = [UIImage imageWithCGImage:cgimg];

[self performSelectorOnMainThread:@selector(setImage:) withObject:newImg waitUntilDone:YES];

The result is my video screen stays black. Can anybody see the error here? Ive been at this for a few hours now and cant figure it out.

Answer 1

I've fixed the problem, the issue was with initializing the CIImage in line:

//Wrong

CIImage *beginImage = image.CIImage;

//Right
CIImage *beginImage = [CIImage imageWithCGImage:imageRef];

As Brad said though, the performance is not acceptable. The video lags behind the audio by about 5 seconds on the iPad2. So I'll look into other solutions for this, but I was still happy to see it working as more of a proof of concept than anything else :)