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I think Carl’s point is interesting. It could be something funky with sleep which if I remember right is a Linux/ Debian based call. Maybe try a different method of making your program hang and see if the problem persists.
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<div>All my best,</div>
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<div>Paul <br>
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<div id="AppleMailSignature" dir="ltr">Sent from the top a castle using a moderately sized European swallow </div>
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On 1 Jun 2019, at 16:17, Lukas Bommes <<a href="mailto:lukas.bommes@gmx.de">lukas.bommes@gmx.de</a>> wrote:<br>
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<div>I'm just buffled because OpenCV uses the same code <span style="font-family: sans-serif;"> (in fact I copied the retrieveFrame funtion from the videoio module 1:1)</span> and it does not show this weird behaviour. There, the runtime of sws_scale is constant
regardless of the calling frequency and retrieving one frame takes always around 1.3 ms.</div>
<div dir="auto">However, my OpenCV build (version 4.1) uses FFMPEG 3.4.6, not 4.1. So, I'm gonna try building my code with FFMPEG 3.4.6 and see if the problem persists. </div>
<div dir="auto">Alternatively, I add a function to the OpenCV videoio module which retrieves frame + motion vectors. However, altering the OpenCV API brings a lot of other challenges.</div>
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<div dir="auto">But maybe someone else has noticed a similar issue with sws_scale in FFMPEG 4.1 before.</div>
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<div class="gmail_extra" dir="auto">Lukas</div>
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<div class="gmail_quote">On 1 Jun 2019 7:04 pm, Carl Eugen Hoyos <<a href="mailto:ceffmpeg@gmail.com">ceffmpeg@gmail.com</a>> wrote:<br type="attribution">
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<p dir="ltr">Am Do., 30. Mai 2019 um 11:59 Uhr schrieb lukas <<a href="mailto:lukas.bommes@gmx.de">lukas.bommes@gmx.de</a>>:</p>
<p dir="ltr">> I wrote a program which extracts motion vectors from a video stream and<br>
> encountered the problem that the runtime of sws_scale changes depending<br>
> on whether I put a sleep command in the main loop of the caller.</p>
<p dir="ltr">Shouldn't you ask this your CPU provider?</p>
<p dir="ltr">Carl Eugen<br>
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