Linux / OBS / USB strangeness

Hi All,

I have a HP PC running ubuntu 20.10 with OBS installed.

Connected via USB I have a Logitech Webcam, a Blue Yetti Microphone, Cheap action cam and a HDMI capture device. I also have a wireless keyboard and mouse combo but I think that’s out of scope.

When I start OBS it seems that I only get either the actioncam OR the HDMI capture but not both. When I open the video capture (v4L2) source and check the device dropdown I only see the Webcam and one of them. I am fairly sure that it only shows the most recently connected device (so unplugging and re-plugging makes it switch).

If I unplug and re-plug things then sometimes I do manage to get both working at the same time but more by luck than judgement I fear.

Does anyone have any idea what’s going on or suggestions for ways to start working this out? I guess a starting place might be something else that is capable of looking for and opening USB video input devices might be a start to rule out an OBS issue but I’m not really sure what to look for.

In case it helps any if I lsubs I get;
Bus 002 Device 004: ID 1bcf:2c99 Sunplus Innovation Technology Inc. FHD Capture
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 046d:c52e Logitech, Inc. MK260 Wireless Combo Receiver
Bus 001 Device 003: ID b58e:9e84 Blue Microphones Yeti Stereo Microphone
Bus 001 Device 010: ID 1b3f:2002 Generalplus Technology Inc. 808 Camera
Bus 001 Device 005: ID 046d:082d Logitech, Inc. HD Pro Webcam C920
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

each time I unplug and replug the device 00x number goes up by 2 for the Generalplus actioncam and by 1 for the Sunplus (which is the HDMI Cap)

I have similar issues with Windows, it’s mostly a USB oddity from what I can tell. Gets even harder if you have something like 3 of the same webcams, which Lifecam Studio am I looking for??? Even my “good” Vaddio USB 3 cameras can have issues after a reboot (camera or computer).

As far as I can tell, it is down to USB enumeration and things may not ever come up as “the same device” after disconnect or power cycle.

Interestingly I have at various points been using 3 of the same camera and whilst they did all seem to move around they did at least all show up ( all the right notes just not necessarily in the right order). This seems to be a slightly different issue although I agree that’s it sounds like some sort of USB enumeration type issue.

I should also mention that audio interfaces may or may not face the same issue, I had a lot of trouble with an old MOTU 4pre not behaving the same after a power cycle. I went with the cheapest XLR input audio mixer I could find on Amazon and it seems to use simple enough drivers that OBS finds it every time now.

Lots of work for a project that is likely to be abandoned again. Trying to move people from the “proper” TV studio mindset to “common” smaller setups is proving aggravating. Again. We need our student to be fluent in both types of productions, studio requires about 8 crew people, OBS requires 1 or 2 crew people. Each has their place ad I know people making money covering business board meetings with a few PTZ cameras and a software based switcher. They are all using a paid product, the paid software/hardware really is better for almost everything. Wirecast, Tricaster, etc. And with NDI the connections are so much more simple!

@Greg_E Have you tried NDI inside OBS?

Not yet. I don’t have any NDI devices, but I might put together a test machine with demo software of NewBlue Titler Live and see how it works. Tricaster is using NDI very effectively (they “developed” it?). You can also run Powerpoint output over network/NDI, again a couple of plugins are needed and people are mostly using it for titles.

I do know that OBS requires a free openNDI plugin to receive the streams.

I have tried RTMP streams from cameras into OBS, and they work fine within the limitations of the streams. Those limitations are that you “can’t” get much less than 2 seconds with most sources. After messing around enough I got my Vaddio cameras from 8 seconds down to 2 seconds, but that isn’t good enough for what I needed to do, went back to the USB3 connections and basically zero latency. I have three older ConferenceShot10 cameras that I picked up like 18 months ago or $40 each, wishing I had bought more of them back then to sell now that the price went way back up for used cameras.

Never thought about RTSP straight into OBS. Does that work with Unifi cameras? I’ve got quite a few of them kicking around.

Not sure about those cameras, but probably. The lag is the real issue, I was never able to get better than 2 second delay and that’s too much for any real work in a studio or live setting. But something to test and see, half a second might be OK for a lot of things.

I do some work with a charity that does a 24hour gaming event and we need loads of cameras there just to cover the site. Any “to camera” pieces would be via something a bit more proper…

Definitely worth a look then

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