Webcam bars when setting exposure | Mainsail | Page 1

gray ether Jan 20, 2023, 9:56 PM

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Hey all. Trying to set up my webcam with v4l2 settings to throw into crowsnest to stop swinging the exposure so aggressively when my LEDs turn on and off just for nicer stuff on startup. However whenever I set exposure_auto=1 and exposure_absoulte=X (x=any number I was using 99 for my use case but any number does it) I get what looks like a conflict between the FPS and the webcam's refresh cycle as shown in this GIF. Is there something I configured wrong? I have also included the -l output as a screenshot because neither CMD or Powershell handle whitespace on copy well thanks Winblows.

hearty wharf Jan 20, 2023, 9:58 PM

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you can set your power line frequenz. you just see your light...

gray ether Jan 20, 2023, 10:01 PM

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I figured since this only started happening when I tried to manually set exposure that that wasnt what was going on.
Like if I swap it back to auto exposure 3 it goes away. And changing power line freq to 2 for USA's 60hz does not change the video output.

opaque gorge Jan 20, 2023, 10:04 PM

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I am sure you using led and use pwm for them so you need to match these both. It could be that 50Hz work better

gray ether Jan 20, 2023, 10:05 PM

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Okay but if that was the case my initial post shows that the settings were using Freq=1 which is 50

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what do you mean by PWM affecting it? i am running these LEDs at 50% because 100 is just way too much light

opaque gorge Jan 20, 2023, 10:10 PM

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As an example my definition 0.0001sec would be 10kHz

gray ether Jan 20, 2023, 10:11 PM

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my cycle_time is currently 0.01

opaque gorge Jan 20, 2023, 10:12 PM

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That would be 100Hz

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So 60Hz would be worse but 50Hz is also not optimal

gray ether Jan 20, 2023, 10:12 PM

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opaque gorge Jan 20, 2023, 10:14 PM

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That flickering is quite normal especially if you start playing around with exposure. And as your led have there own frequency it does not matter where you live

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So you could try to change that to 0.02 (50Hz) or 0.01667 (60Hz) and see if it gets better

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You can not go faster for a software based pwm pin

gray ether Jan 20, 2023, 10:22 PM

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well........ that did solve the flickering problem I set both the LED and the Camera to 60Hz but it seems like it isnt properly taking the values I set in the config for the exposure_absolute. I tried setting it to 99 and I just keep getting different random values when I restart crowsnest.

v4l2ctl: focus_auto=0,focus_absolute=50,power_line_frequency=2,exposure_auto=1,exposure_absolute=99

                  exposure_auto 0x009a0901 (menu)   : min=0 max=3 default=3 value=1
                1: Manual Mode
                3: Aperture Priority Mode
              exposure_absolute 0x009a0902 (int)    : min=3 max=2047 step=1 default=250 value=312

opaque gorge Jan 20, 2023, 10:22 PM

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Let’s bet it’s a Logitech C9xx cam?

gray ether Jan 20, 2023, 10:23 PM

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920 yeah

opaque gorge Jan 20, 2023, 10:24 PM

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We still debugging it https://discord.com/channels/758059413700345988/1064030033552867358

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It seams that Logitech cams have problem with that and need special treatment. There are also reports in the internet about that

gray ether Jan 20, 2023, 10:26 PM

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well thats weird since doing it manually through the CLI works seemingly without issue

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although

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if I try doing it through the CLI the bars return

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just very slowly moving down the image instead of quickly

opaque gorge Jan 20, 2023, 10:26 PM

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Yes we know 🙈. It seams to have to do when you do it relative to starting the stream

gray ether Jan 20, 2023, 10:27 PM

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so long story short better off just sucking it up and using auto exposure and dealing with that

opaque gorge Jan 20, 2023, 10:27 PM

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Currently yes

gray ether Jan 20, 2023, 10:28 PM

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😦 ok

#Webcam bars when setting exposure