ViewCast Comprehensive Guide to Osprey 240e: Understanding the Recalc Feature and Video Cropping

Osprey 240e/450e User Guide

Recalc button

The Recalc button recalculates whichever of the six crop edit boxes you have not filled in. For example, if you set Top, Left, Width, and Height, Recalc calculates Right and Bottom. If you set Top, Left, Right, and Bottom, Recalc calculates Width and Height. Whichever of the vertical group was least recently touched, is the item that is recalculated; similarly with the horizontal group. If you have only changed one box of the group, you can force the order of recalculation by clicking one of the other two boxes. For example: If you have changed Left, and you want to preserve Width (but alter Right), then click on Width before Recalc. If you have changed Left, and want to preserve Right (but alter Width), then click on Right before Recalc.

If your specification results in a crop rectangle that is too large or too small, Recalc adjusts it appropriately. If it can’t set up an allowed size by changing just the third most recently clicked setting, then it tries to change the second most recently clicked setting instead or as well. If it has to, it changes your most recently changed setting.

Recalc also factors in granularity and positioning requirements as required.

In the Default Output Size group, Recalc changes the default output size if Auto Size is checked. If Auto Size is not checked, Recalc leaves the output size alone.

Note: The crop width and height are subject to the granularity requirements of the selected video format, as explained in the previous section. For example, if your video format is I420 and you try to set a crop width of 360, it gets adjusted down to 352.

If you enable cropping, enter in some custom settings, and then disable cropping, an uncropped specification is displayed and your settings disappear from view. However, the driver does remember your custom settings, and if you enable cropping again, they reappear.

Versions 4.2.0 and later of the Osprey AVStream driver can upscale cropped video, up to the reference size.

Cropping rectangles are frame-based rather than field-based. Thus if a crop rectangle is set up defining a 320 x 240 area, then a capture of video sized at 320 x 240 results in video being captured from two fields. You may therefore see interlacing artifacts in the captured video, unless a deinterlacing filter is applied. This may be initially confusing since most users typically think of 320 x 240 video captures only coming from a single field and thus would not have interlaced artifacts. However, in this case, the source video is only 320 x 240 in size (i.e. the crop rectangle) and thus any captured video that is greater than the field height within the crop rectangle (equal to ½ cropped ROI height) results in a scaled capture of multiple fields. Also, the driver uses both fields whenever they are needed to interpolatively scale the output with best possible accuracy.

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