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YUV 420画像の小さな領域を抽出したいだけです。つまり、元の画像の矩形部分のみを含むCVImageBufferRefからCVImageBufferRefを作成します。ここでCVImageBufferRefのサブ画像の抽出
は、私がこれまで試したものです：
上記のコードで- (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBufferRef fromConnection:(AVCaptureConnection *)connection
{
// callback from AVCaptureOutput
//
CVImageBufferRef imageBufferRef = CMSampleBufferGetImageBuffer(sampleBufferRef);
if (imageBufferRef)
{
// Take a subset of buffer to create a smaller image
CVPixelBufferLockBaseAddress(imageBufferRef, 0);
size_t widthY = CVPixelBufferGetWidthOfPlane(imageBufferRef, 0);
size_t widthUV = CVPixelBufferGetWidthOfPlane(imageBufferRef, 1);
size_t heightY = CVPixelBufferGetHeightOfPlane(imageBufferRef, 0);
size_t heightUV = CVPixelBufferGetHeightOfPlane(imageBufferRef, 1);
size_t cropHeightY = 320;
size_t cropWidthY = 320;
size_t cropHeightUV = cropHeightY/2;
size_t cropWidthUV = cropWidthY;
size_t cropY_X0 = widthY/2 - (cropWidthY/2);
size_t cropY_Y0 = heightY/2 - (cropHeightY/2);
size_t cropUV_X0 = widthUV/2 - (cropWidthUV/2);
size_t cropUV_Y0 = heightUV/2 - (cropHeightUV/2);
void *baseAddressY = CVPixelBufferGetBaseAddressOfPlane(imageBufferRef, 0);
void *baseAddressUV = CVPixelBufferGetBaseAddressOfPlane(imageBufferRef, 1);
size_t bytesPerRowY = CVPixelBufferGetBytesPerRowOfPlane(imageBufferRef, 0);
size_t bytesPerRowUV = CVPixelBufferGetBytesPerRowOfPlane(imageBufferRef, 1);
size_t pixelBytesY = bytesPerRowY/widthY;
size_t pixelBytesUV = bytesPerRowUV/widthUV;
void *startPosY = baseAddressY + (cropY_Y0 * bytesPerRowY + cropY_X0 * pixelBytesY);
void *startPosUV = baseAddressUV + (cropUV_Y0 * bytesPerRowUV + cropUV_X0 * pixelBytesUV);
size_t bytesPerRowOut = cropWidthY * pixelBytesY;
size_t sizeY = bytesPerRowOut * cropHeightY;
size_t sizeUV = bytesPerRowOut * cropHeightUV;
unsigned char * pixelY = (unsigned char *)malloc(sizeY);
unsigned char * pixelUV = (unsigned char *)malloc(sizeUV);
for (int i = 0; i < cropHeightY; ++i) {
memcpy(pixelY + i * bytesPerRowOut, startPosY + i * bytesPerRowY, bytesPerRowOut);
}
for (int i = 0; i < cropHeightUV; ++i) {
memcpy(pixelUV + i * bytesPerRowOut, startPosUV + i * bytesPerRowUV, bytesPerRowOut);
}
void *baseAddresses[2] = {pixelY, pixelUV};
size_t planeWidths[2] = {cropWidthY, cropWidthUV};
size_t planeHeights[2] = {cropHeightY, cropHeightUV};
size_t planeBytesPerRow[2] = {bytesPerRowOut, bytesPerRowOut};
// create a new CVImageBufferRef from pixelY and pixelUV
CVPixelBufferRef outBuff;
CVPixelBufferCreateWithPlanarBytes(NULL, cropWidthY, cropHeightY, '420v', NULL, 0, 2, baseAddresses, planeWidths, planeHeights, planeBytesPerRow, NULL, NULL, NULL, &outBuff);
if(logCameraSettings) {
NSLog(@"Original Image Size:\n width:%zu\n height:%zu\n", widthY, heightY);
size_t outWidthY = CVPixelBufferGetWidthOfPlane(outBuff, 0);
size_t outHeightY = CVPixelBufferGetHeightOfPlane(outBuff, 0);
NSLog(@"Modified Image Size:\n width:%zu\n height:%zu\n", outWidthY, outHeightY);
}
// Here would be the place where I actually want to do something with the image
// TEST: show image (in debugger in following method)
[self convertToUIImage:imageBufferRef]; // --> works
[self convertToUIImage:outBuff]; // --> only gray, does not work
// Release the allocated memory
CVPixelBufferUnlockBaseAddress(imageBufferRef,0);
free(pixelY);
free(pixelUV);
}
}
-(void) convertToUIImage:(CVImageBufferRef)imageBuffer
{
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:imageBuffer];
CIContext *temporaryContext = [CIContext contextWithOptions:nil];
CGImageRef videoImage = [temporaryContext
createCGImage:ciImage
fromRect:CGRectMake(0, 0,
CVPixelBufferGetWidth(imageBuffer),
CVPixelBufferGetHeight(imageBuffer))];
// Inspect the following UIImage in debugger.
UIImage *image = [[UIImage alloc] initWithCGImage:videoImage];
CGImageRelease(videoImage);
}
私は私は、デバッガでUIImageとして作成CVImageBufferRefを検査できるようにする以外に目的を持っていない小さな関数convertToUIImageを作成しました。
imageBufferRefを調べると、正しいカメラフィードが表示されます。
しかし、outBuffの検査では、そのカメラのフィードの小さな領域は表示されませんが、正しいサイズのすべてのグレーのパッチが表示されます。
だから私の質問は次のとおりです。
私はここで間違って何をしているのですか？
これは私の目標を達成するための正しい方法ですか？
本当にありがとうございます。前もって感謝します。ここで