IOS – converts CMSampleBufferRef to UIImage

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{

 NSLog(@"imageFromSampleBuffer: called");< br /> // Get a CMSampleBuffer's Core Video image buffer for the media data
 CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
 // Lock the base address of the pixel buffer
 CVPixelBufferLockBaseAddress(imageBuffer, 0);

 // Get the number of bytes per row for the pixel buffer
 void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

 // Get the number of bytes per row for the pixel buffer
 size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
 // Get the pixel buffer width and height
 size_t width = CVPixelBufferGetWidth(imageBuffer);
 size_t height = CVPixelBufferGetHeight(imageBuffer);

 // Create a device-dependent RGB color space
 CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

 // Create a bitmap graphics context with the sample buffer data
 CGContextRef context = CGBitmapContextCreate( baseAddress, width, height, 8,
 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
 // Create a Quartz image from the pixel data in the bitmap graphics context
 CGImageRef quartzImage = CGBitmapContextCreateImage(context );
 // Unlock the pixel buffer
 CVPixelBufferUnlockBaseAddress(imageBuffer,0);


 // Free up the context and color space
 CGContextRelease( context);
 CGColorSpaceRelease(colorSpace);

 // Create an image object from the Quartz image
 UIImage *image = [UIImage imageWithCGImage:quartzImage];
< br /> // Release the Quartz image
 CGImageRelea se(quartzImage);

 return (image);
}

-(void) captureOutput:( AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection
{

 UIImage* image = [self imageFromSampleBuffer:sampleBuffer];
 unsigned char* pixels = [image rgbaPixels];
 double totalLuminance = 0.0;
 for(int p=0;p { 
 totalLuminance += pixels[p]*0.299 + pixels[p+1]*0.587 + pixels[p+2]*0.114;
 }
 totalLuminance /= (image.size.width *image.size.height);
 totalLuminance /= 255.0;
 NSLog(@"totalLuminance %f",totalLuminance);

}

I use AVCaptureSession to shoot video.
But I want to convert the captured image to UI Image.

< p>I found some codes on the Internet:

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{

 NSLog (@"imageFromSampleBuffer: called");
 // Get a CMSampleBuffer's Core Video image buffer for the media data
 CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
 // Lock the base address of the pixel buffer
 CVPixelBufferLockBaseAddress(imageBuffer, 0);

 // Get the number of bytes per row for the pixel buffer
 void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

 // Get the number of byt es per row for the pixel buffer
 size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
 // Get the pixel buffer width and height
 size_t width = CVPixelBufferGetWidth(imageBuffer);
 size_t height = CVPixelBufferGetHeight(imageBuffer);

 // Create a device-dependent RGB color space
 CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

 // Create a bitmap graphics context with the sample buffer data
 CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
 // Create a Quartz image from the pixel data in the bitmap graphics context
 CGImageRef quartzImage = CGBitmapContextCreateImage(context);
 // Unlock the pixel buffer
 CVPixelBufferUnlockBaseAddress(imageBuffer,0);


 / / Free up the conte xt and color space
 CGContextRelease(context);
 CGColorSpaceRelease(colorSpace);

 // Create an image object from the Quartz image
 UIImage *image = [UIImage imageWithCGImage:quartzImage];

 // Release the Quartz image
 CGImageRelease(quartzImage);

 return (image);
)

But I encountered some errors:

06001

Edit:
I also use UIImage to get rgb Color:

-(void) captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection
{
< br /> UIImage* image = [self imageFromSampleBuffer:sampleBuffer];
 unsigned char* pixels = [image rgbaPixels];
 double totalLuminance = 0.0;
 for(int p=0;p< image.size.width*image.size.height*4;p+=4)
 {
 totalLuminance += pixels[p]*0.299 + pixels[p+1]*0.587 + pixels[p+ 2]*0.114;
 }
 totalLuminance /= (i mage.size.width*image.size.height);
 totalLuminance /= 255.0;
 NSLog(@"totalLuminance %f",totalLuminance);

}

Your best choice is to set the capture video data output’s videoSettings to a dictionary that specifies the pixel format you want, you need to set it to Some of the variants of RGB that CGBitmapContext can handle.

The document has a list of all of the pixel formats that Core Video can process. CGBitmapContext only supports a small part of them. You can find it on the Internet The expected format of the code is kCVPixelFormatType_32BGRA, but this may be written for Macs-on iOS devices, kCVPixelFormatType_32ARGB(big-endian) may be faster. Try them on the device and compare the frame rate.