方法1不是根據Apple's documentation(「物理旋轉緩衝區確實帶有性能成本,因此只有在需要時才請求旋轉」)的優選方法。方法2適用於我,但如果我在不支持轉換「元數據」的應用程序上播放視頻,則視頻無法正確旋轉。方法3是我所做的。
我認爲在您試圖將圖像數據從vImageRotate...
直接傳遞到AVAssetWriterInputPixelBufferAdaptor
之前它會崩潰。您必須先創建CVPixelBufferRef
。這裏是我的代碼:
if ([self.videoWriterInput isReadyForMoreMediaData])
{
// Rotate buffer first and then write to adaptor
CMTime sampleTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
CVPixelBufferRef rotatedBuffer = [self correctBufferOrientation:sampleBuffer];
[self.videoWriterInputAdaptor appendPixelBuffer:rotatedBuffer withPresentationTime:sampleTime];
CVBufferRelease(rotatedBuffer);
}
執行的VIMAGE旋轉引用的功能是::
/* rotationConstant:
* 0 -- rotate 0 degrees (simply copy the data from src to dest)
* 1 -- rotate 90 degrees counterclockwise
* 2 -- rotate 180 degress
* 3 -- rotate 270 degrees counterclockwise
*/
- (CVPixelBufferRef)rotateBuffer:(CMSampleBufferRef)sampleBuffer withConstant:(uint8_t)rotationConstant
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer, 0);
OSType pixelFormatType = CVPixelBufferGetPixelFormatType(imageBuffer);
NSAssert(pixelFormatType == kCVPixelFormatType_32ARGB, @"Code works only with 32ARGB format. Test/adapt for other formats!");
const size_t kAlignment_32ARGB = 32;
const size_t kBytesPerPixel_32ARGB = 4;
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
BOOL rotatePerpendicular = (rotateDirection == 1) || (rotateDirection == 3); // Use enumeration values here
const size_t outWidth = rotatePerpendicular ? height : width;
const size_t outHeight = rotatePerpendicular ? width : height;
size_t bytesPerRowOut = kBytesPerPixel_32ARGB * ceil(outWidth * 1.0/kAlignment_32ARGB) * kAlignment_32ARGB;
const size_t dstSize = bytesPerRowOut * outHeight * sizeof(unsigned char);
void *srcBuff = CVPixelBufferGetBaseAddress(imageBuffer);
unsigned char *dstBuff = (unsigned char *)malloc(dstSize);
vImage_Buffer inbuff = {srcBuff, height, width, bytesPerRow};
vImage_Buffer outbuff = {dstBuff, outHeight, outWidth, bytesPerRowOut};
uint8_t bgColor[4] = {0, 0, 0, 0};
vImage_Error err = vImageRotate90_ARGB8888(&inbuff, &outbuff, rotationConstant, bgColor, 0);
if (err != kvImageNoError)
{
NSLog(@"%ld", err);
}
CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
CVPixelBufferRef rotatedBuffer = NULL;
CVPixelBufferCreateWithBytes(NULL,
outWidth,
outHeight,
pixelFormatType,
outbuff.data,
bytesPerRowOut,
freePixelBufferDataAfterRelease,
NULL,
NULL,
&rotatedBuffer);
return rotatedBuffer;
}
void freePixelBufferDataAfterRelease(void *releaseRefCon, const void *baseAddress)
{
// Free the memory we malloced for the vImage rotation
free((void *)baseAddress);
}
注:
裏面的captureOutput:didOutputSampleBuffer:fromConnection:
我寫它插入適配器前旋轉框架您可能喜歡使用枚舉爲rotationConstant
。類似的東西(不調用MOVRotateDirectionUnknown
此功能):
typedef NS_ENUM(uint8_t, MOVRotateDirection)
{
MOVRotateDirectionNone = 0,
MOVRotateDirectionCounterclockwise90,
MOVRotateDirectionCounterclockwise180,
MOVRotateDirectionCounterclockwise270,
MOVRotateDirectionUnknown
};
注意:如果你需要IOSurface
的支持,你應該使用CVPixelBufferCreate
代替CVPixelBufferCreateWithBytes
和字節的數據直接傳遞到它:
NSDictionary *pixelBufferAttributes = @{ (NSString *)kCVPixelBufferIOSurfacePropertiesKey : @{} };
CVPixelBufferCreate(kCFAllocatorDefault,
outWidth,
outHeight,
pixelFormatType,
(__bridge CFDictionaryRef)(pixelBufferAttributes),
&rotatedBuffer);
CVPixelBufferLockBaseAddress(rotatedBuffer, 0);
uint8_t *dest = CVPixelBufferGetBaseAddress(rotatedBuffer);
memcpy(dest, outbuff.data, bytesPerRowOut * outHeight);
CVPixelBufferUnlockBaseAddress(rotatedBuffer, 0);
嗨,你有沒有找到解決方案? – DaNLtR