Classes/RosyWriterCPURenderer.m

 
/*
     File: RosyWriterCPURenderer.m
 Abstract: The RosyWriter CPU-based effect renderer
  Version: 2.1
 
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 */
 
#import "RosyWriterCPURenderer.h"
 
@implementation RosyWriterCPURenderer
 
#pragma mark RosyWriterRenderer
 
- (BOOL)operatesInPlace
{
    return YES;
}
 
- (FourCharCode)inputPixelFormat
{
    return kCVPixelFormatType_32BGRA;
}
 
- (void)prepareForInputWithFormatDescription:(CMFormatDescriptionRef)inputFormatDescription outputRetainedBufferCountHint:(size_t)outputRetainedBufferCountHint
{
    // nothing to do, we are stateless
}
 
- (void)reset
{
    // nothing to do, we are stateless
}
 
- (CVPixelBufferRef)copyRenderedPixelBuffer:(CVPixelBufferRef)pixelBuffer
{   
    const int kBytesPerPixel = 4;
    
    CVPixelBufferLockBaseAddress( pixelBuffer, 0 );
    
    int bufferWidth = (int)CVPixelBufferGetWidth( pixelBuffer );
    int bufferHeight = (int)CVPixelBufferGetHeight( pixelBuffer );
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow( pixelBuffer );
    uint8_t *baseAddress = CVPixelBufferGetBaseAddress( pixelBuffer );
    
    for ( int row = 0; row < bufferHeight; row++ )
    {
        uint8_t *pixel = baseAddress + row * bytesPerRow;
        for ( int column = 0; column < bufferWidth; column++ )
        {
            pixel[1] = 0; // De-green (second pixel in BGRA is green)
            pixel += kBytesPerPixel;
        }
    }
    
    CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
    
    return (CVPixelBufferRef)CFRetain( pixelBuffer );
}
 
@end