<p dir="auto">[x] Request</p>
<p dir="auto">Request to FIX OpenCv 2.4.13.6 cmake source to build OpenCv_World24136.DLL</p>
<p dir="auto">minimum build x86 vc12,</p>
<p dir="auto">because I can only build opencv_world with 3.x in vc14,vc15</p>
<h5 dir="auto">System information (version)</h5>

<ul dir="auto">
<li>OpenCV =&gt; 3.4.3 and 4.0.1</li>
<li>Operating System / Platform =&gt;Snapdragon 845</li>
<li>Compiler =&gt; Android NDK 18.1.5063045</li>
</ul>
<h5 dir="auto">Detailed description</h5>

<p dir="auto">I have a face recognition algorithm running on snapdragon 845 platform. This code was compiled by using the official release OpenCV 3.4.3 Android package (see here <a href="https://sourceforge.net/projects/opencvlibrary/files/opencv-android/3.4.3/opencv-3.4.3-android-sdk.zip/download" rel="nofollow">https://sourceforge.net/projects/opencvlibrary/files/opencv-android/3.4.3/opencv-3.4.3-android-sdk.zip/download</a>). It takes around <strong>500ms</strong> to recognize a face.<br>
I don't specify any PreferableTarget and PreferableBackend then I guess by default, the code runs on CPU of snapdragon 845.</p>
<p dir="auto">Today, I upgrade to OpenCV 4.0.1 (the official Android package can be found here <a href="https://sourceforge.net/projects/opencvlibrary/files/4.0.1/opencv-4.0.1-android-sdk.zip/download" rel="nofollow">https://sourceforge.net/projects/opencvlibrary/files/4.0.1/opencv-4.0.1-android-sdk.zip/download</a>). I don't change anything in my Android studio. In low level of my C++ code, I have to change only an enum from CV_YUV2RGB_NV21 to cv::COLOR_YUV2RGB_NV21. (I think this change cannot be the cause of the problem). Now, it takes around <strong>650ms</strong> to recognize a face.</p>
<p dir="auto">Bref: the same Android studio configuration, the same NDK, 99% the same code, the same tested platform but there is a huge regression in terms of processing time between OpenCV 3.4.3 and OpenCV 4.0.1 !!</p>
<p dir="auto">The network that I use to do face recognition is ArcFace (see here <a href="https://github.com/deepinsight/insightface">https://github.com/deepinsight/insightface</a>). The authors provide a trained network under Caffe form.</p>
<p dir="auto">Does anyone observe similar regression ?<br>
Thanks</p>