Reworked ImageResampler

[Thinner77]

Summary

Hi,

this is a reworked version of ImageResampler. IMHO there is no need to check pixelformat and flipmode for every pixel.

Benchmark was done with 1920x1080@30FPS/YUYV input, cropping 10/10/5/5, signal detection disabled, on Raspberry Pi Zero 2W, cpu usage from htop, for different pixeldecimations (pixeldecimation=frametime in ms/cpu usage in %)

org: 1=223ms/103%, 2=67ms/105%, 3=37ms/109%, 4=33ms/78%, 5=33ms/64%, 6=33ms/56%, 7=33ms/51%, 8=33ms/48%, 16=33ms/43%
new: 1=153ms/103%, 2=49ms/105%, 3=33ms/89% , 4=33ms/66%, 5=33ms/55%, 6=33ms/49%, 7=33ms/47%, 8=33ms/45%, 16=33ms/43%

Benchmark code was added for V4L2-grabber. For 30 FPS minimal frametime is 33ms.

wbr

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• Bugfix
• Feature
• Code style update
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[Lord-Grey]

@Thinner77 Thanks you for your contribution.
The refactoring makes sense.
I assume you tested the different Pixelformats?

[Thinner77]

@Lord-Grey Hi, i couldn't check all pixelformats, because i don't have input devices for all. I have double-checked code for NV12 and I420 for uOffset/vOffset code. And i have tested flipmode (BGR24 is still flipped 😉). As i have only rearranged code to move the case switches outside the nested for loops i don't expect any problems for the untested ones. I have no doubt that it will work, otherwise i wouldn't have created the PR. Feel free to refute me. 😄 Review and test the code, tell me if there is something wrong, i will check. wbr

[Lord-Grey]

Thank you!

[Thinner77]

@Lord-Grey Hi, are you aware that the benchmarking code is still in there? It shouldn't be a problem since the output is only in debug mode. But it could fill the logs. I just wanted to point that out. wbr

[Lord-Grey]

Hi @Thinner77 ohhh. Thanks for pointing out.
I assumed that the benchmark code was left in, but disabled.
I should have checked 😄

[Lord-Grey]

Disabled the benchmark code