KSPROPERTY_CAMERACONTROL_EXTENDED_OPTIMIZATIONHINT (application performance strategy)

Article
02/27/2023

Camera drivers may optimize their capture operation based on hints provided by the application. This property informs the driver to set its performance strategy based on what operation is likely used the most. For example, when optimized for photo, the camera driver may program the sensor to optimize sensor exposure speed and resolution for lower latency from photo capture trigger to image capture. Similarly, when optimized for video, the camera driver may program the sensor for higher frame rate but at a lower resolution.

Usage summary table

Get	Set	Target	Property descriptor type	Property value type
Yes	Yes	Filter	KSPROPERTY	KSCAMERA_EXTENDEDPROP_HEADER

The property value (operation data) contains a KSCAMERA_EXTENDEDPROP_HEADER structure and a KSCAMERA_EXTENDEDPROP_VALUE structure.

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.

The Capability member of KSCAMERA_EXTENDEDPROP_HEADER contains a bitwise OR combination of one or more of the following optimization hints.

Optimization hint	Description
KSCAMERA_EXTENDEDPROP_OPTIMIZATION_PHOTO	Camera operation is optimized for photos
KSCAMERA_EXTENDEDPROP_OPTIMIZATION_VIDEO	Camera operation is optimized for video

The Flags member of KSCAMERA_EXTENDEDPROP_HEADER contains the optimization currently set for the camera (one value).

The default optimization type is KSCAMERA_EXTENDEDPROP_OPTIMIZATION_PHOTO. If this property is supported by the camera driver, then both optimization types must be supported.

This property control is synchronous and not cancelable.

Remarks

Optimization modes

KSCAMERA_EXTENDEDPROP_OPTIMIZATION_PHOTO

All camera drivers must be in this mode until explicitly informed to use the KSCAMERA_EXTENDEDPROP_OPTIMIZATION_VIDEO mode. The purpose of this mode is to optimize the camera hardware for photo operations. Video operations must still be functional in this mode.

KSCAMERA_EXTENDEDPROP_OPTIMIZATION_VIDEO

This mode indicates that the camera will likely be used for video operations. The camera driver should optimize the hardware for video operations for this mode. Photo operations must be functional, but there resource usage priority is for video operations.

Getting the property

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	KSCAMERA_EXTENDEDPROP_FILTERSCOPE (0xFFFFFFFF)
Size	sizeof(KSCAMERA_EXTENDEDPROP_HEADER) + sizeof(KSCAMERA_EXTENDEDPROP_VALUE)
Result	0
Capability	Optimization values supported
Flags	The current optimization value setting

If no optimization mode was previously set, then the driver sets Flags to KSCAMERA_EXTENDEDPROP_OPTIMIZATION_PHOTO (default).

Setting the property

When the property is set, a KSPROPERTY_TYPE_SET request, the Flags member of KSCAMERA_EXTENDEDPROP_HEADER will contain the optimization mode to set.

Requirements

Version: Available starting with Windows 8.1

Header: Ksmedia.h (include Ksmedia.h)