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[15:58] <pistache> hi ! i'm having some trouble in finding the cause of image corruption on UVC webcams, both with USB 2.0 and USB 3.0 (and two different models of cameras)
[16:01] <pistache> it looks like decoding errors, doesn't seem related to the power line frequency, happens a lot with YUYV and less with YV12 or MJPEG
[16:02] <pistache> I thought it was related to the camera model (an USB3 8MP webcam), unable to properly encode images at 3264x2448, but we are now experiencing it with an USB2 8MP webcam
[16:02] <pistache> I forgot to say that corruption only happens on some frames, depending on many factors
[16:04] <pistache> with the USB 3.0 webcam, corruption can be triggered by enabling wifi and sending/receiving data
[16:04] <pistache> but this does not happen with the USB 2.0 webcam
[16:05] <pistache> we experienced this problem with 2 different cameras, with 2 different laptops (Asus and Toshiba, both with Intel Broadwell)
[16:07] <pistache> it only happens at 3264x2449 (here is an example of such glitch: http://pix.toile-libre.org/upload/original/1475251587.jpg)
[16:08] <pistache> I tried to enable quirks=0x80 and quirks=0x128, but it did not change anything
[16:09] <pistache> some environmental conditions that I don't understand seem make the corrupt frames more frequent in some places that other
[16:10] <pistache> I strongly suspected the eletrical grid frequency, but using an UPS did not make them away
[16:12] <pistache> I can observe that switching from YUYV to YV12 really reduces the glitches, so I deduce that I can lower their probability by lowering the bitrate
[16:15] <pistache> the laptops are low-end (asus eeebook E502MA), we did not experience these problems with higher end laptops
[16:15] <pistache> would anyone have an idea of how to investigate the cause of these glitches ?
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[18:46] <andrey_utkin> pistache, do these cameras work flawlessly on windows?
[18:46] <andrey_utkin> pistache, have you tried complaining to manufacturer?
[19:19] <pistache> andrey_utkin: they come from two different manufacturers
[19:20] <pistache> the pro
[19:20] <pistache> the problem happens with two different cameras, and two different laptops, but only at the highest resolution
[19:21] <pistache> they are both cheap cameras and both cheap laptops
[19:22] <pistache> the glitches happen a LOT in hospitals, so I suspect EMIs have something to do with this
[19:29] <andrey_utkin> anyway, complaining to manufacturer is legit action. Not very useful, but...
[19:30] <andrey_utkin> if that's EMI... then asking here is futile :) Test it outside of hostpitals :)
[19:31] <andrey_utkin> Also test it in Faraday cage :)
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