How to set frame rates of DirectShow video devices?

[TIS Stefan]

Hi Using USB cameras with WDM DirectShow drivers in MAX does not allow to set frame rates. Only one frame rate is given, e.g. 30 fps. Worse: 60 fps is possible with the specific camera, but can not be set in MAX. Also if it is not possible to set frame rates, it is not possible to run two cameras in parallel on one USB controller, because the bandwidth exceeds. Is there a solution? Stefan

[Christian Mergl]

Our IMAQdx driver is capable in changing settings of USB cameras, which are provided through DirectShow. So if it's not settable in MAX, it's simply not available through DirectShow.

Does Winnov provide a tool to change the settings of the camera?

You could also contact support@winnov.de

Christian

[TIS Stefan]

Hello Christian, Thank you for your reply. I must admit, I do not understand your answer and I also do not understand, what relation a third party company has to my USB cameras. Stefan

[Christian Mergl]

Isn't WDM DirectShow you mentioned in your first post from Winnov?

Anyhow, if the attribute is not settable in MAX, it's not available via DirectShow.

Christian

[TIS Stefan]

Christian >Isn't WDM DirectShow you mentioned in your first post from Winnov? No. >Anyhow, if the attribute is not settable in MAX, it's not available via DirectShow. Ok, I have to accept this fact. I suppose, even in future version, this will be not possible, right?

[Christian Mergl]

Well, unlike using Firewire and Gigabit Ethernet cameras which have standards like GeniCam or GigEVision, there is no standard for USB image acquisition right now. That's why we use DirectShow as common interface for USB cameras. There are efforts to create a standard for USB cameras too but there are not very much big vendors right now to promote it. Most of the big and well known vendors choose GigE, and the difference in pricing between USB and GigE is not that much anymore.

Christian

[TIS Stefan]

Christian, I know that GigE and FireWire are supported much better in LabVIEW. I work for a camera manufacturer and we sell all of these camera types. Unfortunately many of our LabVIEW using customers want to use USB cameras too. Sometime quite more than one camera in one system. This is the reason, why I asked.

[BlueCheese]

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@TIS Stefan wrote:
Hi Using USB cameras with WDM DirectShow drivers in MAX does not allow to set frame rates. Only one frame rate is given, e.g. 30 fps. Worse: 60 fps is possible with the specific camera, but can not be set in MAX. Also if it is not possible to set frame rates, it is not possible to run two cameras in parallel on one USB controller, because the bandwidth exceeds. Is there a solution? Stefan

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Hi Stefan,

IMAQdx supports changing the framerate if the camera driver implements it in the standard DirectShow mechanism. The way it is defined, the camera provides a list of video modes that each include an image format, an image size, and a range of possible frame rates. IMAQdx enumerates these and expands out the possible combinations as different video modes available. You should see these available as a Video Mode drop-down box on the Acquisition tab in MAX. You can also of course access these programatically via the API in LabVIEW.

Eric

[TIS Stefan]

Hi Eric, I thought the same, when I first saw this image. But: different frame rates mean 1 resolution e.g. 320x240 and *different* frame rates. The list in the image shows for each frame rate only *one* resolution. Stefan

[TIS Stefan]

I would excpect: 640x480 RGB24 60fps 640x480 RGB24 30fps 640x480 RGB24 15fps 640x480 RGB24 7.50fps and so on.