Question

我捕获了视频，并在captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer委托中对其进行了一些分析。但过一会儿就不会调用此方法。然后调用captureOutput:(AVCaptureOutput *)output didDropSampleBuffer委托。

当我在didOutputSampleBuffer中什么也不做时，一切都很好。
我在此委托中运行张量流模型。这会导致问题。

问题：
问题在于，当调用didDropSampleBuffer时，didOutputSampleBuffer不会再次调用。

我的解决方案：
我的解决方案是停止并启动avCaptureSession。但这导致额外的内存使用！最终导致我的应用崩溃。

 - (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
    {
        // ******  do heavy work in this delegate *********
        graph = [TensorflowGraph new];
        predictions = [graph runModelOnPixelBuffer:pixelBuffer orientation: UIDeviceOrientationPortrait CardRect: _vwRect];
    }

    - (void)captureOutput:(AVCaptureOutput *)output didDropSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
    {
                CFTypeRef droppedFrameReason = CMGetAttachment(sampleBuffer, kCMSampleBufferAttachmentKey_DroppedFrameReason, NULL);
                NSLog(@"dropped frame, reason: %@", droppedFrameReason);
    }

---->丢帧，原因：OutOfBuffers

根据[https://developer.apple.com/library/archive/technotes/tn2445/_index.html]：

此情况通常是由客户端保留缓冲区导致的时间过长，可以通过将缓冲区返回到提供者。

如何将缓冲区退还给提供者？

已编辑

执行CGImageRef cgImage = [context createCGImage:resized fromRect:resized.extent];行11次后，将调用didDropSampleBuffer。评论CFRelease(pixelBuffer)的结果没有差异。这是否意味着不释放pixelBuffer？

CFRetain(pixelBuffer);
CVPixelBufferLockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);

CIImage* ciImage = [[CIImage alloc] initWithCVPixelBuffer:pixelBuffer];
ciImage = [ciImage imageByCroppingToRect:cropRect];

CGAffineTransform transform = CGAffineTransformIdentity;
CGFloat angle = 0.0;

transform = CGAffineTransformRotate(transform, angle);
CIImage* resized = [ciImage imageByApplyingTransform:transform];

CIContext *context = [CIContext contextWithOptions:nil];

CGImageRef cgImage = [context createCGImage:resized fromRect:resized.extent]; // *********************************

UIImage* _res = [[UIImage alloc] initWithCGImage:cgImage];


CFRelease(pixelBuffer);

1

didDropSampleBuffer在iOS中经常被调用

0 个答案: