how to display data of yuv format without converting rgb in OpenGL ES?

问题

I have being study about OpenGL ES for iOS. I wonder that data of YUV format is can display without converting RGB. In most, the yuv data have to convert RGB for display. But, converting process is very slow, Then, that is not display smoothly. So, I would like to try to dispaly YUV data without convert to RGB. Is it possible? If possible, what can I do? Please, let me give a advice.

回答1:

I think it is not possible in OpenGL ES to display YUV data without convert to RGB data.

回答2:

You can do this very easily using OpenGL ES 2.0 shaders. I use this technique for my super-fast iOS camera app SnappyCam. The fragment shader would perform the matrix multiplication to take you from YCbCr ("YUV") to RGB. You can have each {Y, Cb, Cr} channel in a separate GL_LUMINANCE texture, or combine the {Cb, Cr} textures together using a GL_LUMINANCE_ALPHA texture if your chrominance data is already interleaved (Apple call this a bi-planar format).

See my related answer to the question YUV to RGBA on Apple A4, should I use shaders or NEON? here on StackOverflow.

You may also do this using the fixed rendering pipeline of ES 1.1, but I haven't tried it. I would look toward the the texture blending functions, e.g. given in this OpenGL Texture Combiners Wiki Page.

回答3:

Is you are looking solution for IOS, iPhone application then there are solution for that.

This is way convert CMSampleBufferRef to UIImage when video pixel type is set as kCVPixelFormatType_420YpCbCr8BiPlanarFullRange

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

    @autoreleasepool {
        // 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 plane pixel buffer
        void *baseAddress = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);

        // Get the number of bytes per row for the plane pixel buffer
        size_t bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer,0);
        // Get the pixel buffer width and height
        size_t width = CVPixelBufferGetWidth(imageBuffer);
        size_t height = CVPixelBufferGetHeight(imageBuffer);

        // Create a device-dependent gray color space
        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

        // Create a bitmap graphics context with the sample buffer data
        CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                     bytesPerRow, colorSpace, kCGImageAlphaNone);
        // 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];

        // Release the Quartz image
        CGImageRelease(quartzImage);

        return (image);
    }
}

If you are looking for Mobile devices then i can provide others to.

来源：https://stackoverflow.com/questions/8531981/how-to-display-data-of-yuv-format-without-converting-rgb-in-opengl-es

标签

opengl-es

rgb

yuv