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KSPROPERTY_CAMERACONTROL_EXTENDED_PHOTOMAXFRAMERATE

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This property provides the maximum capture frame rate for a camera when it is in photo sequence mode.

Usage Summary Table

Get Set Target Property descriptor type Property value type

Yes

Yes

Pin

KSPROPERTY

KSCAMERA_EXTENDEDPROP_HEADER

The property value (operation data) contains a KSCAMERA_EXTENDEDPROP_HEADER structure and a KSCAMERA_EXTENDEDPROP_VALUE structure. The maximum photo frame rate in frames per second is set or returned as value in KSCAMERA_EXTENDEDPROP_VALUE.

There are no flags set in the Flags member of KSCAMERA_EXTENDEDPROP_HEADER for this property.

The total property data size is sizeof(KSCAMERA_EXTENDEDPROP_HEADER) + sizeof(KSCAMERA_EXTENDEDPROP_VALUE). The Size member of KSCAMERA_EXTENDEDPROP_HEADER is set to this total property data size.

This property control is asynchronous and not cancelable.

Remarks

When responding to a KSPROPERTY_TYPE_GET request, the driver sets the members of the KSCAMERA_EXTENDEDPROP_HEADER to the following.

Member Value
Version 1
PinId The pin ID for the photo pin.
Size

sizeof(KSCAMERA_EXTENDEDPROP_HEADER) +

sizeof(KSCAMERA_EXTENDEDPROP_VALUE)
Result

An error value resulting from the attempt to read the max frame rate.

Otherwise, 0.
Capability KSCAMERA_EXTENDEDPROP_CAPS_ASYNCCONTROL
Flags 0

The frame rate value is set in the Ratio member of KSCAMERA_EXTENDEDPROP_VALUE. Ratio.HighPart contains the numerator of the frame rate and Ratio.LowPart contains the denominator of the frame rate.

When the driver is in photo sequence mode, it may be necessary to limit the maximum frame rate of the photo capture. This is to ensure that “moment in time” capture scenarios, with a certain number of history frames, are contained within a configured time span. For example, based on memory constraints, if the application wishes to capture 1 second worth of past history, it’s necessary to cap the capture rate so only N number of frames are needed.

When set, the driver must use the frame rate provided even if the camera can capture frames fast then the requested rate. If necessary, the driver can drop extra frames to accommodate the requested rate.

Setting the maximum frame rate value to 0 (0 for the HighPart and 0 for the LowPart of the Ratio) clears the maximum frame rate setting in the driver and has the same effect as asking the driver to provide frames as fast as possible. Once the frame rate is set to 0, any subsequent query will return the value of the maximum frame rate possible for the camera driver.

Requirements

Version

Available starting with Windows 8.1.

Header

 Ksmedia.h (include Ksmedia.h)