如何将CMSampleBuffer转为UIImage

2018-09-12

如何将一个CMSampleBuffer转为一个UIImage呢？

方法1：VTCreateCGImageFromCVPixelBuffer

CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
CGImageRef cgImage = nil;
VTCreateCGImageFromCVPixelBuffer(pixelBuffer, nil, &cgImage);
UIImage *image = [[UIImage alloc] initWithCGImage:cgImage];
return image;

这个方法只能在iOS9以上执行，而且我还遇到一个问题，连续调用VTCreateCGImageFromCVPixelBuffer 15次后，会将AVCaptureSession的video连接给断开，非常神奇 - -！,以至于老是卡主我的预览。

方法2：

CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    
CIContext *temporaryContext = [CIContext contextWithOptions:nil];
CGImageRef videoImage = [temporaryContext
                             createCGImage:ciImage
                             fromRect:CGRectMake(0, 0,
                                               CVPixelBufferGetWidth(pixelBuffer),
                                                 CVPixelBufferGetHeight(pixelBuffer))];
    
UIImage *uiImage = [UIImage imageWithCGImage:videoImage];
CGImageRelease(videoImage);
return uiImage;

目前用的就是这个。

方法3:

这是第三方库SRRecorder中使用的方法，不过还是需要pixeltype为kCVPixelFormatType_32BGRA才行。

+ (UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer {
    // 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];
    UIImage *image = [UIImage imageWithCGImage:quartzImage scale:1.0f orientation:UIImageOrientationRight];
    
    // Release the Quartz image
    CGImageRelease(quartzImage);
    
    return (image);
}