PCAM_FREE_BW_ROUTINE callback function (usbcamdi.h)

Article
02/22/2024

[CamFreeBandwidth is not supported and may be altered or unavailable in the future. Instead, use CamFreeBandwidthEx. ]

A camera minidriver's CamFreeBandwidth callback function selects an alternate setting within the USB video streaming interface that uses no bandwidth.

Syntax

PCAM_FREE_BW_ROUTINE PcamFreeBwRoutine;

NTSTATUS PcamFreeBwRoutine(
  PDEVICE_OBJECT BusDeviceObject,
  PVOID DeviceContext
)
{...}

Parameters

BusDeviceObject

Pointer to the camera minidriver's device object created by the USB hub.

DeviceContext

Pointer to the camera minidriver's device context.

Return value

CamFreeBandwidth returns STATUS_SUCCESS or an appropriate error code.

Remarks

Camera minidrivers that must maintain backward compatibility with the original USBCAMD must use the USBCAMD_DEVICE_DATA structure and its associated callback functions (that is, callback functions that do not contain the "Ex" suffix).

USBCAMD calls the camera minidriver's CamFreeBandwidth callback function after the isochronous video stream has stopped.

Typically, this function calls the USBCAMD_SelectAlternateInterface service to select the correct alternate interface and prepare for streaming video.

This function is required.

Requirements

Requirement	Value
Target Platform	Desktop
Header	usbcamdi.h (include Usbcamdi.h)