AVFundation 中CMSampleBufferRef转U

AVCaptureVideoDataOutput 实际上只支持一下三种格式的输出

• kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange (默认)

• kCVPixelFormatType_420YpCbCr8BiPlanarFullRange

• kCVPixelFormatType_32BGRA

方法一：

- (UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer {
    
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVPixelBuffer:imageBuffer];
    CIContext *temporaryContext = [CIContext contextWithOptions:nil];
    CGImageRef videoImage = [temporaryContext createCGImage:ciImage fromRect:CGRectMake(0, 0, CVPixelBufferGetWidth(imageBuffer), CVPixelBufferGetHeight(imageBuffer))];
    
    UIImage *image = [[UIImage alloc] initWithCGImage:videoImage];
    CGImageRelease(videoImage);
    
    return image;
}

方法二：只支持kCVPixelFormatType_32BGRA。需要就那将AVCaptureVideoDataOutput设置为kCVPixelFormatType_32BGRA。

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
    // 为媒体数据设置一个CMSampleBuffer的Core Video图像缓存对象
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    // 锁定pixel buffer的基地址
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    
    // 得到pixel buffer的基地址
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
    
    // 得到pixel buffer的行字节数
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    // 得到pixel buffer的宽和高
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    
    // 创建一个依赖于设备的RGB颜色空间
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    // 用抽样缓存的数据创建一个位图格式的图形上下文（graphics context）对象
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    // 根据这个位图context中的像素数据创建一个Quartz image对象
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    // 解锁pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
    
    //释放context和颜色空间
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    
    // 用Quartz image创建一个UIImage对象image
    //UIImage *image = [UIImage imageWithCGImage:quartzImage];
    UIImage *image = [UIImage imageWithCGImage:quartzImage scale:1.0f orientation:UIImageOrientationRight];
    
    // 释放Quartz image对象
    CGImageRelease(quartzImage);
    
    return (image);
    
}

参考：

• Getting actual NSString of AvCaptureVideoDataOutput availableVideoCVPixelFormatTypes
• convert CMSampleBufferRef to UIImage