optimization - direct-show web camera - rPI4 server and Windows10/64b client

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optimization - direct-show web camera - rPI4 server and Windows10/64b client

We have some purchased VH licences for rPI4 - recent server version and recent Raspbian(<14days) and latest client.
The application has two direct-show cameras (640x512) plus USB-6009 (National Instruments). The latter is low data volume DAQ.
Ehernet is a peer-peer cable. VH installed as service both places.

We see that the video is slower than with direct USB cables into the client which is probably to expect, but worse we see a fairly frequent freeze and lagging of the images. Freeze is now and then fatal and the application need to be restarted.

We tried to tweek the compression threshold but found no evidently better setting - probably a threshold of 584 is slightly better than default 384, but it is hard to tell.

Are there other handles we can try to turn to improve the smoothness and stability.

br henning


The pi4 should easily be able to handle that video camera. Im assuming its 30 frames per second?

What about if you dont use the USB-6009 at the same time? Is the video ok then?

You can leave the compression at 384 as it wont make much difference.

Another thing to check, bring up the latency graph when the video is running and see what it looks like.

Right click USB Hubs->Raspberry Hub->Properties->Latency

thanks for the useful hints.

thanks for the useful hints. I am suspecting the USB-6009. Yes frame rate is about 30/s.

Latency: Right click USB Hubs->Raspberry Hub->Properties->Latency
this is on the windows VH client (Right?) - but there is no field labeled Latency in properties.
It has:
Version: 4.08,
Connected for,
max devices,
Connecton ID,
Serial number,
Ignored dev,

No latency field. ,,,
Can it be because I access the Win10 client via remote desktop?


Next to Address there is (Latency)

If the USB-6009 is the problem you will need to use a separate virtualhere usbserver just for it. It might be because its senting lots of little packets while the camera is streaming

This is strange: "Next to

This is strange: "Next to Address there is (Latency)".
There is no "latency" on the dialog I have
Are there any way to attach a picture (of the Server Properties Dialog)?

I see the latency link to

I see the latency link to Server A - on client 1 (PC1) - local login.
I dont see the latency link to Server A - on client 2 (PC2) - local login.
I dont see the latency link to Server A - on client 2 (PC2) - remote desktop login from PC1.
Both clients are win 10.
So PC2 never shows latency link. Is that weird? Anyway not too important.


Actually i just remembered, if the client is running as a service the "Latency" link will not be shown. Uninstall the client as a service by right clicking USB Hubs->Uninstalll Service and just run the client again normally


Dont think it is the USB-6009 which is the (main) culprit.
With one camera on VH server it works fine and steady frame rate (only with camera on VH). With two camera's (only with cameras on VH) the frame rate drops and gets erratic - like if they share the same bandwidth of data (which they do of course) but the sharing ratio is erratic. Removing one brings it back on steady rate.


OK yes i misread your original post, and thought you were using one camera all the time, so yes two will not work well because of the bandwidth sharing issue. With two isochronous devices sending a lot of data the bandwidth wont be shared equally because linux is non-deterministic and the cpu is processing execution threads in a non-predictable manner.

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