ViewCast Osprey PCI, User Manual

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Setting Driver Properties
68 ViewCast
The Granularity controls show you the granularity restrictions for the selected video format, as assist
you in choosing crop and output size that observe those restrictions.
Since the preview and capture pins may be set to different color formats, they may have different
granularities. When the Crop tab is opened, the two drop boxes titled Capture and Preview are
initialized to the current or most recently used format for the selected pin.
If the Pin Select setting is Capture , only the Capture granularity box will be enabled; similarly for
Preview. The two small read-only edit boxes to the right of the group show the horizontal and
vertical granularities for the selected color format for the selected pin type.
If the Pin Select setting is Both , both the Capture and Preview drop boxes are enabled, and the two
boxes to the right of the group show the worst-case granularity that works for both the Capture and
Preview color formats. For example, if the Capture color format is I420 and the Preview color format
is YUY2, the resultant granularity is I420’s more stringent 16 x 2 requirement.
The granularity and alignment settings affect values you subsequently enter for crop width, crop
height, and default output width and height – they will be adjusted to these granularities.
Adjustments are made when you click
Recalc , Apply , or OK .
You can change the video format in the drop-down list, so that granularities are set for a different
format.
Note: This does not automatically cause the pin to have this format – you still have to select that
format using the Pin Properties dialog or via your application. It just ensures that the sizes you
select will work correctly when you do select this color format in the application.
If you set up your crops with a less restrictive granularity (for example, YUY2) and then capture with
a more restricted granularity (for example, I420), the driver may automatically adjust the video crop
and/or output size without notifying you. Or, the capture may fail. You may also find that in the Pin
Properties dialog the default size you wanted is not listed – because it is not a legal size for this
format.
If you click none as the color format(s), the minimum granularity and alignment adjustments are
applied to your crop and size data.
If you click any as the video format, the coarsest granularity required by any of the available formats
is applied to your crop and size data. In practice, any is the same as YVU9, that is, 16 x 4. You are
guaranteed that your crop and output sizes will never be adjusted, regardless of what video format
you select now or in the future.
Enable Cropping
If you uncheck Enable Cropping , your video will not be cropped regardless of any crop settings you
might previously have made. The edit boxes showing the edges, height, and width of your crop will
be read-only and will show settings for full-frame, uncropped video.