PCAM_FREE_BW_ROUTINE_EX callback function (usbcamdi.h)

Article
04/21/2022

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

Syntax

PCAM_FREE_BW_ROUTINE_EX PcamFreeBwRoutineEx;

NTSTATUS PcamFreeBwRoutineEx(
  PDEVICE_OBJECT BusDeviceObject,
  PVOID DeviceContext,
  ULONG STreamNumber
)
{...}

Parameters

BusDeviceObject

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

DeviceContext

Pointer to the camera minidriver's device context.

STreamNumber

Indicates stream number.

Return value

CamFreeBandwidthEx returns STATUS_SUCCESS or an appropriate error code.

Remarks

USBCAMD calls the camera minidriver's CamFreeBandwidthEx 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.

The original USBCAMD does not call CamFreeBandwidthEx.

This function is required.

Requirements

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