[iOS] Camera

AVCaptureVideoDataOutputSampleBufferDelegate

새로운 video frame 객체를 만들때 불린다.

(void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection;

 

CMSampleBufferRef -> CVImageBufferRef -> MLRImage

- (MLRImage *)convertToMLImage {
    UIImageOrientation imageOrientation = [self imageOrientationFromSampleBuffer];
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(self.sampleBuffer);

    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);
    size_t padding = bytesPerRow - width * 4;

    Byte *bytes = (Byte *)malloc(sizeof(Byte) * width * height * 4);
    if (!bytes)
        return nil;

    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
    size_t offset = 0;
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            size_t rgbPixelOffset  = (i * width + j) * 4;
            size_t rgbaPixelOffset = (i * width + j) * 4 + offset;

            bytes[rgbPixelOffset + 0] = baseAddress[rgbaPixelOffset + 2];
            bytes[rgbPixelOffset + 1] = baseAddress[rgbaPixelOffset + 1];
            bytes[rgbPixelOffset + 2] = baseAddress[rgbaPixelOffset + 0];
            bytes[rgbPixelOffset + 3] = baseAddress[rgbaPixelOffset + 3];
        }
        offset += padding;
    }

    NSMutableData *rgbaData = [NSMutableData dataWithBytesNoCopy:bytes length:width * height * 4];
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
    
    return [MLRImage createImageWithRawData:rgbaData rawImageSize:CGSizeMake(width, height) imageOrientation:imageOrientation];
}