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Epiphan Systems Inc.


Configuring DirectShow options

From the Capture menu you can select Configure Device and then select the DirectShow tab to configure DirectShow options.

You can also configure DirectShow options from the VGA2USB control panel application.

Figure 42: Configuring DirectShow options

Fix Resolution
Control the image resolution reported to DirectShow and so used by DirectShow-compatible applications. You can use this option to cause DirectShow to expand or shrink the image recorded by DirectShow-compatible video capture applications. The available resolutions range from 640 x 480 to 2560 x 1600.
Default Image
Select an image to be sent to DirectShow if the Frame Grabber is not sending images to the video capture workstation. This option replaces what would otherwise be a blank screen with a static image that would be captured by DirectShow-compatible image capture applications.
Scaling
If Fix Resolution is set to a resolution that does not match the actual resolution of the video signal you can select Pixel Resize to have the Epiphan USB device driver resize the image (either shrink or expand it) to match the fixed resolution. Pixel Resize is a simple resizing method that adds or removes pixels as required to resize an image.
If you set scaling to No Resizing the Epiphan USB device driver does not resize the image sent to DirectShow. If the actual resolution of the video signal is smaller than the fixed resolution, the image appears in DirectShow compatible video capture applications with a border around it. If the actual resolution is larger than the fixed resolution, the image appears cropped in DirectShow compatible video capture applications.
Flip image vertically
Select this option to turn the captured image displayed on the video capture application upside down. If you select this option, the image in recorded videos, the image that is copied when you select Copy from the Edit menu, printed images, and broadcasted images are also upside down. Images saved by selecting Save from the File menu and recorded image files are not affected by this option.
Limit frame rate to
Select Limit frame rate to and set a frame rate that is lower than the frame rate at which your Frame Grabber can capture images. You can reduce the frame rate to reduce the number of images captured by the Frame Grabber. You may want to reduce the frame rate to reduce the load on the video capture workstation or to reduce the size of recorded video files.
For example, if the Frame Grabber can capture up to 60 frames a second (fps), this frame rate may use close to 100% CPU usage on some video capture workstations. To reduce load on the video capture workstation you can limit the frame rate to 30 fps without loosing very much useful data.
The valid frame rate range is from 0.01 to 60 fps. The default frame rate is 30 fps.
Fix frame rate
Select fix frame rate to force the frame rate to always be the same as the limited frame rate. If the limited frame rate is less than the actual frame rate some frames will be missed. If the limited frame rate is higher than the actual frame rate some frames will be duplicated.


Epiphan Systems Inc.
Frame Grabber User Guide, 1 February 2009
www.Epiphan.com
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