Re: [linux-uvc-devel] select-timeout errors OpenCV

[Jason P. <jn...@uw...>]

Lovely, thanks!  Is there an easy way to get OpenCV or an application to
detect the select-timeout error specifically, other than just detecting
that the frames weren't acquired?

-J

On Thu, Oct 24, 2019 at 12:09 PM Dmitry Mikushin <dm...@ke...>
wrote:

> Sure, I use this nice code: https://github.com/ralight/usb-reset
>
> The error means the camera chip is out of the game due to various reasons.
> It could be a bug in firmware, voltage deviation, on-chip logic failure,
> etc. Select is just a system call, which does resource polling. Resource
> has not delivered data in time, hence the timeout message. The host system
> cannot tell what exactly has happened - the resource just went offline,
> it's all it knows.
>
> Kind regards,
> - Dmitry.
>
>
> чт, 24 окт. 2019 г. в 20:48, Jason Pitt <jn...@uw...>:
>
>> Is there a way to do a reset in software?  I guess I could wire the USB
>> through a relay and trip it occasionally, but that seems a rather inelegant
>> solution.
>>
>> What would the issue be with the cabling? The camera is on a gantry robot
>> and an ~3-4 meter USB cable in a drag chain.  Does this error mean packets
>> are getting lost/garbled?  What does this error actually represent?
>>
>> -J
>>
>> On Thu, Oct 24, 2019 at 11:27 AM Dmitry Mikushin <dm...@ke...>
>> wrote:
>>
>>> To my experience, many cameras run into select error sooner or later.
>>> Here we must elaborate that by "camera" we really mean "camera sensor +
>>> postprocessing chip". This postprocessing chip comes in a single package
>>> within the webcam. A small PCB has its own circuits (transceiver, FPGA, USB
>>> interface, etc.) and firmware, which is often unavailable for user
>>> inspection. Select error likely means that the chip/firmware has failed,
>>> and the webcam is put into unresponsive state. Several possible workarounds:
>>>
>>> 1) Reset the camera periodically
>>> 2) Ensure the USB cable is good, not affected by strong electromagnetic
>>> noise or intensive physical movement
>>> 3) Do not use USB cameras with separate postprocessing chip - instead,
>>> use MIPI/CSI2 cameras such as in cell phones, write your own
>>> postprocessing software and be fully responsible for its failures (see e.g.
>>> camera/driver for Raspberry Pi).
>>>
>>> Kind regards,
>>> - Dmitry Mikushin.
>>>
>>>
>>> чт, 24 окт. 2019 г. в 20:11, Jason Pitt <jn...@uw...>:
>>>
>>>> Hi-
>>>>
>>>> I'm having issues with a webcam throwing select-timeout errors after
>>>> several days of image acquisition.
>>>>
>>>> dmesg yields: [251952.411582] uvcvideo: Non-zero status (-71) in video
>>>> completion handler.
>>>>
>>>> over and over and over
>>>>
>>>> Would appreciate any help in getting this camera working more stably as
>>>> it's on a robotic system that needs to run for months at a time.
>>>>
>>>> thanks
>>>> -J
>>>>
>>>>
>>>> --
>>>> /*
>>>> Jason Pitt PhD                                   206.616.1193
>>>> Kaeberlein Lab                                   jn...@uw...
>>>> University of Washington
>>>> Department of Pathology
>>>> Health Sciences Building                    Box 357470
>>>> 1989 NE Pacific Street
>>>> Seattle, WA 98195
>>>> */
>>>> _______________________________________________
>>>> Linux-uvc-devel mailing list
>>>> Lin...@li...
>>>> https://lists.sourceforge.net/lists/listinfo/linux-uvc-devel
>>>>
>>>
>>
>> --
>> /*
>> Jason Pitt PhD                                   206.616.1193
>> Kaeberlein Lab                                   jn...@uw...
>> University of Washington
>> Department of Pathology
>> Health Sciences Building                    Box 357470
>> 1989 NE Pacific Street
>> Seattle, WA 98195
>> */
>>
>

-- 
/*
Jason Pitt PhD                                   206.616.1193
Kaeberlein Lab                                   jn...@uw...
University of Washington
Department of Pathology
Health Sciences Building                    Box 357470
1989 NE Pacific Street
Seattle, WA 98195
*/