CVPixelBuffer

https://www.cnblogs.com/psklf/p/7700834.html

https://stackoverflow.com/questions/16475737/convert-uiimage-to-cmsamplebufferref

- (CGImageRef) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer // Create a CGImageRef from sample buffer data
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer,0);        // Lock the image buffer

    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);   // Get information of the image
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGImageRef newImage = CGBitmapContextCreateImage(newContext);
    CGContextRelease(newContext);

    CGColorSpaceRelease(colorSpace);
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
    /* CVBufferRelease(imageBuffer); */  // do not call this!

    return newImage;
}

//This is a function that I use in my GPUImage framework to resize an incoming CMSampleBufferRef and place the scaled results within a CVPixelBufferRef that you provide:

void GPUImageCreateResizedSampleBuffer(CVPixelBufferRef cameraFrame, CGSize finalSize, CMSampleBufferRef *sampleBuffer)
{
    // CVPixelBufferCreateWithPlanarBytes for YUV input

    CGSize originalSize = CGSizeMake(CVPixelBufferGetWidth(cameraFrame), CVPixelBufferGetHeight(cameraFrame));

    CVPixelBufferLockBaseAddress(cameraFrame, 0);
    GLubyte *sourceImageBytes =  CVPixelBufferGetBaseAddress(cameraFrame);
    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, sourceImageBytes, CVPixelBufferGetBytesPerRow(cameraFrame) * originalSize.height, NULL);
    CGColorSpaceRef genericRGBColorspace = CGColorSpaceCreateDeviceRGB();
    CGImageRef cgImageFromBytes = CGImageCreate((int)originalSize.width, (int)originalSize.height, 8, 32, CVPixelBufferGetBytesPerRow(cameraFrame), genericRGBColorspace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst, dataProvider, NULL, NO, kCGRenderingIntentDefault);

    GLubyte *imageData = (GLubyte *) calloc(1, (int)finalSize.width * (int)finalSize.height * 4);

    CGContextRef imageContext = CGBitmapContextCreate(imageData, (int)finalSize.width, (int)finalSize.height, 8, (int)finalSize.width * 4, genericRGBColorspace,  kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    CGContextDrawImage(imageContext, CGRectMake(0.0, 0.0, finalSize.width, finalSize.height), cgImageFromBytes);
    CGImageRelease(cgImageFromBytes);
    CGContextRelease(imageContext);
    CGColorSpaceRelease(genericRGBColorspace);
    CGDataProviderRelease(dataProvider);

    CVPixelBufferRef pixel_buffer = NULL;
    CVPixelBufferCreateWithBytes(kCFAllocatorDefault, finalSize.width, finalSize.height, kCVPixelFormatType_32BGRA, imageData, finalSize.width * 4, stillImageDataReleaseCallback, NULL, NULL, &pixel_buffer);
    CMVideoFormatDescriptionRef videoInfo = NULL;
    CMVideoFormatDescriptionCreateForImageBuffer(NULL, pixel_buffer, &videoInfo);

    CMTime frameTime = CMTimeMake(1, 30);
    CMSampleTimingInfo timing = {frameTime, frameTime, kCMTimeInvalid};

    CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, pixel_buffer, YES, NULL, NULL, videoInfo, &timing, sampleBuffer);
    CFRelease(videoInfo);
    CVPixelBufferRelease(pixel_buffer);
}
//It doesn't take you all the way to creating a CMSampleBufferRef, but as weichsel points out, you only need the CVPixelBufferRef for encoding the video.