Bug Report Multiple >1 webcams from same vendor, same model. only 1 works

[exoloner]

This is a video capture device issue, bug.
Using Windows version 22.0.2 64bits (last version 09/2018 )
Just got a bunch of same HD 720P webcam model from same vendor, same model, and distributed them nicely around the reharsal studio.
They are visible in the listbox :

The thing is that just 1 of them is working ok.
The rest are shown in the Listbox, with same name, but selecting renders a black rectangle.

I've double checked myself, with a .NET client, that there's no trouble in getting surfaces from various devices with same name but diferent guid.
So I assume is a issue in OBS. So solution is purchase diferent vendor/model for each webcam you want to use?
Thanks for reading team!

 

[Tomasz Góral]

To test use VLC, run 2x VLC and connect to first and second webcam.
If you see picture, is the OBS problem, but if you not see picture, is the problem in your computer (like USB insufficient bandwidth) or webcam driver.

 

[exoloner]

Hi! Thanks for reading and giving me a test.
VLC Works fine with the 3 webcams, as seen here:

...VLC lists the second identical webcams adding a "#1" substring to the name:

Can you check it for yourself: pick 2 or more webcams same brand/model and try to reproduce VLC test and use them in OBS.
Is this "feature" checked?

Thanks Tomasz!

 

[Tomasz Góral]

Some times if you choice on list camera, list changed position, if choice first camera, in next time select other position.
You use 32bit or 64bit version ?
Some drivers have trouble (32bit driver with OBS 64bit).
VLC is in version 32 or 64bit?

 

[exoloner]

I've tested both OBS builds : 32 and 64 bits
I've tested both VLC (32 and 64 bits)
Windows 7 Pro 64 bits

I've cleared all scenes and created the capture devices from scratch [*] :

• First created a capture device with a crap webcam named "cam SD"
• then created a second "cam HD 1" with a modern webcam listed by OBS as "HD 720p webcam"
• ...finally, any attempt to create a third capture device fails. I assume the first 2 webcam are already being used, and unusable. Choosing the second "HD 720p webcam" results in blank preview and nothing but a tiny red dot pretending to be the rectangle, like this :

This is[*] how I try to create the third capture device with a "same name" webcam device (becaus it's same model/vendor).

My theory is that OBS does not manage devices Listbox control selection event, in a proper way.

I assume the source code is in here > https://github.com/obsproject/obs-studio
Maybe in obs-studio/UI/window-basic-source-select.cpp ¿?!
I'm not familiarized with OBS source code, and could take me ages to check the right lines of codes and files where this happens and check this issue, (or is not an issue)

The selected capture device using the Listbox's SelectedItem, must be by the index number, not by the name, because device name may not be unique.
[*]

 

[Harold]

The only brand cameras I know of that play nice in this sort of setup is logitech. The problem is most likely a limitation of the driver.

 

[exoloner]

The only brand cameras I know of that play nice in this sort of setup is logitech. The problem is most likely a limitation of the driver.

Not sure, but is not a driver limitation. Myself modified this dshow webcam app(C#.NET+cpp) an it's running both cameras from same vendor and same device name, yet diferent guid resource
https://www.codeproject.com/Articles/10248/Motion-Detection-Algorithms

If someone expertised in OBS internals could take a look at here /obs-studio/blob/master/UI/window-basic-source-select.cpp
maybe the ListBox click event is taking the same system resource id's already taken, thus provoking a ...NULL render. makes sense.
In other words : Behind the

names, OBS is using the same exact device driver id

So: Nobody ever at OBS team tested 2,3,4... webcams exactly the same model and vendor?
:o

 

[kimbrasil]

I recommend to add your problem in the GitHub discussions https://github.com/obsproject/obs-studio/pulls
and circumvent using many of VCam softwares available. Hope this help you.

 

[exoloner]

I recommend to add your problem in the GitHub discussions https://github.com/obsproject/obs-studio/pulls
and circumvent using many of VCam softwares available. Hope this help you.

Nice idea! thanks! seems a bit technical here, and maybe I can help myself the project.

 

[Harold]

So: Nobody ever at OBS team tested 2,3,4... webcams exactly the same model and vendor?
:o

Logitech C920s play nice and yes. up to 5.

 

[AlexanderHarizanov]

Same issue here...
When i run 2 logitech 922 pro stream cams only 1 Can run at 720 or 1080p And 2nd runs only at 800x600 or 640...
This needs to be fixed...
Also not usb bandwith issue cause i even tried it on a usb 2 And 3 port that are on different controlers

 

[Harold]

And yet I got FIVE C920s running at 1080p on one computer.

 

[AlexanderHarizanov]

And yet I got FIVE C920s running at 1080p on one computer.

and yet I cant only run the 2 at once at 1080p/720p 1 and below 800x600 the 2nd...
let me guess ...
somehow the issue is on my side...

 

[carlmmii]

Yes. 3 c922's here (w/ other cams/capture devices), 2 running at 720p60 and 1 at 1080p30 with no issue.

Make absolutely sure your host controller balancing is as you expect it to be (use a usb monitoring program to verify host controller trees), don't try to extend the usb cables past their rated lengths for passive/active extenders, and don't use your front panel ports if at all possible.

 

[Harold]

And definitely don't use usb hubs.

 

[Suslik V]

@exoloner Please post a log with your issue! Here's how...

 

[AlexanderHarizanov]

Yes. 3 c922's here (w/ other cams/capture devices), 2 running at 720p60 and 1 at 1080p30 with no issue.

Make absolutely sure your host controller balancing is as you expect it to be (use a usb monitoring program to verify host controller trees), don't try to extend the usb cables past their rated lengths for passive/active extenders, and don't use your front panel ports if at all possible.

scratch that...
after the last update of OBS that I got now both work fine even with cable extenders (previous version they didn't (and that was with no extender cables at all)
same ports no windows updates no changes at all beside OBS updated

 

[Suslik V]

@AlexanderHarizanov , the last change to module that handles the DirectShow input of OBS Studio is dated Nov 27, 2017. The last significant change to source is about 5 month as was implemented and its more like special use ("synchronous_activate") that cannot be enabled from UI. So, you just missed something in your PC.

 

[AlexanderHarizanov]

@AlexanderHarizanov , the last change to module that handles the DirectShow input of OBS Studio is dated Nov 27, 2017. The last significant change to source is about 5 month as was implemented and its more like special use ("synchronous_activate") that cannot be enabled from UI. So, you just missed something in your PC.

well...
pc windows or settings haven't been touched in 6+ months...

 

[philipPF]

Hi, exact same problem than the OP for me, I solved it by forcing two distinct names for my devices (generic name "HD USB Camera").

It was a real pain to do on windows, I had to change values in the registry to have distinct devices naming ! I'll post soon some screenshots, I followed this tutorial but in reality the change to do was in another registry path https://www.avoiderrors.com/rename-devices-device-manager/

I'll post some details asap !
Cheers