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I'm doing live video processing on iOS using OpenCV, without using CvVideoCamera. My app is crashing due to Memory Pressure.

The native iOS camera calls this function every time a frame is captured:

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection
{
    //convert the frame to a UIImage:
    UIImage *image = [self imageFromSampleBuffer:sampleBuffer];

    //convert the UIImage to a Mat:
    Mat srcMat = [self cvMatFromUIImage:image];

    //Process the Mat:
    Mat dst, cdst;
    Canny(srcMat, dst, 50, 200, 3);
    cvtColor(dst, cdst, COLOR_GRAY2BGR);

    std::vector<Vec4i> lines;
    HoughLinesP(dst, lines, 1, CV_PI/180, 50, 50, 10 );
    for( size_t i = 0; i < lines.size(); i++ )
    {
        Vec4i l = lines[i];
        cv::line( cdst, cv::Point(l[0], l[1]), cv::Point(l[2], l[3]), Scalar(0,0,255), 3, LINE_AA);
    }
}

The app crashes about 15 seconds later due to memory pressure.

The calls to imageFromSampleBuffer and cvMatFromUIImage don't cause any memory leaks, it's the processing I do after //Process the Mat: that's responsible for it. But I can't figure out why...

It looks like the Mat objects are staying in memory, but aren't Mat objects released automatically?

I'm doing live video processing on iOS using OpenCV, without using CvVideoCamera. My app is crashing due to Memory Pressure.

The native iOS camera calls this function every time a frame is captured:

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection
{
    //convert the frame to a UIImage:
    UIImage *image = [self imageFromSampleBuffer:sampleBuffer];

    //convert the UIImage to a Mat:
    Mat srcMat = [self cvMatFromUIImage:image];

    //Process the Mat:
    Mat dst, cdst;
    Canny(srcMat, dst, 50, 200, 3);
    cvtColor(dst, cdst, COLOR_GRAY2BGR);

    std::vector<Vec4i> lines;
    HoughLinesP(dst, lines, 1, CV_PI/180, 50, 50, 10 );
    for( size_t i = 0; i < lines.size(); i++ )
    {
        Vec4i l = lines[i];
        cv::line( cdst, cv::Point(l[0], l[1]), cv::Point(l[2], l[3]), Scalar(0,0,255), 3, LINE_AA);
    }
}

The app crashes about 15 seconds later due to memory pressure.

The calls to imageFromSampleBuffer and cvMatFromUIImage don't cause any memory leaks, it's the processing After some investigation, I do after //Process the Mat: that's responsible for it. But found that the call to Canny() is responsible, but I can't figure out why...

It looks like the Mat objects are staying in memory, but aren't Mat objects released automatically?

I'm doing live video processing on iOS using OpenCV, without using CvVideoCamera. My app is crashing due to Memory Pressure.

The native iOS camera calls this function every time a frame is captured:

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection
{
    //convert the frame to a UIImage:
    UIImage *image = [self imageFromSampleBuffer:sampleBuffer];

    //convert the UIImage to a Mat:
    Mat srcMat = [self cvMatFromUIImage:image];

    //Process the Mat:
    Mat dst, cdst;
    Canny(srcMat, dst, 50, 200, 3);
    cvtColor(dst, cdst, COLOR_GRAY2BGR);
}

The app crashes about 15 seconds later due to memory pressure.

After some investigation, I found that the call to Canny() is responsible, but I can't figure out why...

It looks like the Mat objects are staying in memory, but aren't Mat objects released automatically?