CMSampleBufferRef转换

参考链接：https://blog.****.net/shenyi0106/article/details/47004039

https://blog.****.net/jeffasd/article/details/78181856?locationNum=1&fps=1

音频内容

AudioStreamBasicDescription outputFormat = *(CMAudioFormatDescriptionGetStreamBasicDescription(CMSampleBufferGetFormatDescription(sampleBuffer)));

size_t nSize = CMSampleBufferGetTotalSampleSize(sampleBuffer);

CMBlockBufferRef databuf = CMSampleBufferGetDataBuffer(sampleBuffer);

视频内容

转换操作：

#define clamp(a) (a>255?255:(a<0?0:a))
- (UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer,);

    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    uint8_t *yBuffer = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, );
    size_t yPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, );
    uint8_t *cbCrBuffer = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, );
    size_t cbCrPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, );

    int bytesPerPixel = ;
    uint8_t *rgbBuffer = malloc(width * height * bytesPerPixel);

    for(int y = ; y < height; y++) {
        uint8_t *rgbBufferLine = &rgbBuffer[y * width * bytesPerPixel];
        uint8_t *yBufferLine = &yBuffer[y * yPitch];
        uint8_t *cbCrBufferLine = &cbCrBuffer[(y >> ) * cbCrPitch];

        for(int x = ; x < width; x++) {
            int16_t y = yBufferLine[x];
            int16_t cb = cbCrBufferLine[x & ~] - ;
            int16_t cr = cbCrBufferLine[x | ] - ;

            uint8_t *rgbOutput = &rgbBufferLine[x*bytesPerPixel];

            int16_t r = (int16_t)roundf( y + cr *  1.4 );
            int16_t g = (int16_t)roundf( y + cb * -0.343 + cr * -0.711 );
            int16_t b = (int16_t)roundf( y + cb *  1.765);

            rgbOutput[] = 0xff;
            rgbOutput[] = clamp(b);
            rgbOutput[] = clamp(g);
            rgbOutput[] = clamp(r);
        }
    }

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(rgbBuffer, width, height, , width * bytesPerPixel, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    UIImage *image = [UIImage imageWithCGImage:quartzImage];

    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    CGImageRelease(quartzImage);
    free(rgbBuffer);

    CVPixelBufferUnlockBaseAddress(imageBuffer, );

    return image;
}