我正在尝试根据用户的输入裁剪CMSampleBufferRef
ratio
,下面的代码采用CMSampleBufferRef,将其转换为CVImageBufferRef并使用CVPixelBuffer基于以下方式裁剪内部图像它的字节。此过程的目标是使用裁剪和缩放的CVPixelBufferRef写入视频
- (CVPixelBufferRef)modifyImage:(CMSampleBufferRef) sampleBuffer {
@synchronized (self) {
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// Lock the image buffer
CVPixelBufferLockBaseAddress(imageBuffer,0);
// Get information about the image
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
CVPixelBufferRef pxbuffer;
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
[NSNumber numberWithInt:720], kCVPixelBufferWidthKey,
[NSNumber numberWithInt:1280], kCVPixelBufferHeightKey,
nil];
NSInteger tempWidth = (NSInteger) (width / ratio);
NSInteger tempHeight = (NSInteger) (height / ratio);
NSInteger baseAddressStart = 100 + 100 * bytesPerRow;
CVReturn status = CVPixelBufferCreateWithBytes(kCFAllocatorDefault, tempWidth, tempHeight, kCVPixelFormatType_32BGRA, &baseAddress[baseAddressStart], bytesPerRow, MyPixelBufferReleaseCallback, NULL, (CFDictionaryRef)options, &pxbuffer);
if (status != 0) {
CKLog(@"%d", status);
return NULL;
}
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
return pxbuffer;
}
}
一切正常,但是当我尝试使用此方法将其写入视频的输出时,它会一直接收内存警告。如果我保持相同的比例,那就好了
- (void)writeBufferFrame:(CMSampleBufferRef)sampleBuffer pixelBuffer:(CVPixelBufferRef)pixelBuffer {
CMTime lastSampleTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
if(self.videoWriter.status != AVAssetWriterStatusWriting)
{
CKLog(@"%d", self.videoWriter.status);
[self.videoWriter startWriting];
[self.videoWriter startSessionAtSourceTime:lastSampleTime];
}
CVPixelBufferRef pxbuffer = [self modifyImage:sampleBuffer];
BOOL success = [self.avAdaptor appendPixelBuffer:pxbuffer withPresentationTime:lastSampleTime];
if (!success)
NSLog(@"Warning: Unable to write buffer to video");
}
我还尝试了使用CMSampleBufferRef和CGContext的不同方法。如果你能为这里的任何方法提供解决方案,我可以给你全部分数
答案 0 :(得分:1)
尝试在对-CVPixelBufferLockBaseAddress和-CVPixelBufferUnlockBaseAddress的两次调用中使用kCVPixelBufferLock_ReadOnly标志。 有时这个问题可以通过复制像素缓冲区来解决。执行一次分配:
unsigned char *data = (unsigned char*)malloc(ySize * sizeof(unsigned char));
之后,将数据从pixelBuffer复制到数据
size_t size = height * bytesPerRow;
memcpy(data,baseAddress,size);
之后,使用数据。希望,这会有所帮助。