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Unread 11-04-2016, 21:41
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RobotPy Guy
AKA: Dustin Spicuzza
FRC #1418 (), FRC #1973, FRC #4796, FRC #6367 ()
Team Role: Mentor
 
Join Date: Dec 2008
Rookie Year: 2003
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Re: Problems with three cameras

Quote:
Originally Posted by techhelpbb View Post
Hm, so it definitely looks like the lifecam devices don't have serial numbers or unique identifiers of any kind on them. There are symlinks setup at /dev/v4l/by-id and /dev/v4l/by-path. As you might imagine, the by-id symlinks are useless (only one appears even with multiple devices plugged in), but the by-path symlinks appear to be related to the position on the USB hub, and the information I've found appears to indicate that it should be a stable path.

Initial experiments on a roborio with a hub indicate that the by-path positions are indeed stable across device insert/removals and reboots. I'm not 100% sure of the best way to test this, but I'll add the information to mjpg-streamer's documentation anyways.
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Maintainer of RobotPy - Python for FRC
Creator of pyfrc (Robot Simulator + utilities for Python) and pynetworktables/pynetworktables2js (NetworkTables for Python & Javascript)

2017 Season: Teams #1973, #4796, #6369
Team #1418 (remote mentor): Newton Quarterfinalists, 2016 Chesapeake District Champion, 2x Innovation in Control award, 2x district event winner
Team #1418: 2015 DC Regional Innovation In Control Award, #2 seed; 2014 VA Industrial Design Award; 2014 Finalists in DC & VA
Team #2423: 2012 & 2013 Boston Regional Innovation in Control Award


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