I'm just buffled because OpenCV uses the same code (in fact I copied the retrieveFrame funtion from the videoio module 1:1) 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.
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.
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.
But maybe someone else has noticed a similar issue with sws_scale in FFMPEG 4.1 before.
Lukas
On 1 Jun 2019 7:04 pm, Carl Eugen Hoyos <[email protected]> wrote:
Am Do., 30. Mai 2019 um 11:59 Uhr schrieb lukas <[email protected]>:
> I wrote a program which extracts motion vectors from a video stream and
> encountered the problem that the runtime of sws_scale changes depending
> on whether I put a sleep command in the main loop of the caller.Shouldn't you ask this your CPU provider?
Carl Eugen
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