ktemby
Posts: 11
Joined: Mon Dec 01, 2014 3:46 am

Purple artifacts in Pi Camera Module Raspivid

Sun Jan 03, 2016 3:09 pm

Experiencing an intermittent purple artifact in video taken by raspivid on this camera module.
Image

Module was working perfectly for around one month before this occurred. I'm presently attempting to remotely debug.

Attempted power cycle, no effect.
Attempted replacing power module no effect.
No other observed issues with the pi module.
No complaints from raspivid.
Next step will be to reconfirm connector cable, but presently remote.

Curious whether anyone has come across this failure mode, and whether there's a flag that's set somewhere that allows us to detect it.

Cheers

d4n14l
Posts: 3
Joined: Sun Jan 24, 2016 10:40 pm

Re: Purple artifacts in Pi Camera Module Raspivid

Mon Jan 25, 2016 1:15 am

I have this same issue! I will be running some tests later on this week to see if I can nail down the root of it, but I have a feeling that it's related to the input power on the pi camera. However, it would be nice if someone else having the issue could chime in!

6by9
Raspberry Pi Engineer & Forum Moderator
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Re: Purple artifacts in Pi Camera Module Raspivid

Mon Jan 25, 2016 10:06 am

The CSI protocol layer has per line checksums. I suspect that you are getting errors on some lines and not on others, either due to power supply or external interference.

There is a layer of GPU logging that you should be able to turn on to confirm that we're getting errors detected. A quick looks says "vcgencmd set_logging level=0xc00" before the run, and "sudo vcdbg log msg" to show the log AFTER the run. There is so much logging under that level that often vcdbg log msg can't read it out fast enough before the circular buffer has wrapped, hence doing it after the run.
The lines you'll be looking for will include "unicam_int_callback error [0]: <something>".
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I'm not interested in doing contracts for bespoke functionality - please don't ask.

jamesh
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Re: Purple artifacts in Pi Camera Module Raspivid

Mon Jan 25, 2016 10:37 am

I'd also double check all the connections - including the sunny connector on the camera board itself.
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d4n14l
Posts: 3
Joined: Sun Jan 24, 2016 10:40 pm

Re: Purple artifacts in Pi Camera Module Raspivid

Mon Feb 29, 2016 10:24 pm

Just to update: this seems to be cause by a large amount of EMI running near either the Pi or the Pi Cam cable, not the power supply to the pi itself (though that would also be a likely culprit, we were able to eliminate that possibility through the creation of a variety of input power filters).

As the pi cam cable is so uniquely shaped, there is not much choice other than to A) shield your pi cam cable and pi or B) shield the source of the noise, as the use of ferrite beads is not possible with the ribbon cable.

Good luck and if I have any updates I will report back.

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 11246
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Purple artifacts in Pi Camera Module Raspivid

Mon Feb 29, 2016 11:06 pm

You don't say if you're using the standard Pi camera flex or a longer one. If you need the length, then there are adapter boards around that have very short ribbon cables and use an hdmi lead between. You may get better screening from an hdmi lead.
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

d4n14l
Posts: 3
Joined: Sun Jan 24, 2016 10:40 pm

Re: Purple artifacts in Pi Camera Module Raspivid

Mon Feb 29, 2016 11:38 pm

While I would get better screening from an HDMI cable, this is unfortunately not possible due to the fact that the Pi I am using has a third-party Pi Cam multiplexer being used to connect more than 1 camera. Unfortunately, the complex setup leaves only enough room to use the ribbon cables without the HDMI adaptor.

But yes, an HDMI adaptor would most likely provide far better shielding. :)

JimColvin
Posts: 3
Joined: Fri Jul 19, 2019 6:50 pm

Re: Purple artifacts in Pi Camera Module Raspivid

Fri Oct 09, 2020 3:27 am

a ferrite ribbon cable filter slipped on the cable near the pi csi port will solve the problem such as 28R0898-100. 2nd option is to standoff the cable away from other conductors/chassis.

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