PCAM_ALLOCATE_BW_ROUTINE_EX callback function (usbcamdi.h)
A camera minidriver's CamAllocateBandwidthEx callback function selects the appropriate alternate setting within the USB video streaming interface and prepares the device to stream.
Syntax
PCAM_ALLOCATE_BW_ROUTINE_EX PcamAllocateBwRoutineEx;
NTSTATUS PcamAllocateBwRoutineEx(
PDEVICE_OBJECT BusDeviceObject,
PVOID DeviceContext,
PULONG RawFrameLength,
PVOID Format,
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.
RawFrameLength
Specifies the size, in bytes, of the raw frame data from the packet stream.
Format
Pointer to a KS_DATAFORMAT_VIDEOINFOHEADER structure associated with this stream.
StreamNumber
Specifies the stream number.
Return value
CamAllocateBandwidthEx returns STATUS_SUCCESS or an appropriate error code.
Remarks
USBCAMD calls the camera minidriver's CamAllocateBandwidthEx callback function immediately before the isochronous video capture stream is started. It is called in connection with a Run command.
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 CamAllocateBandwidthEx.
This function is required.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | usbcamdi.h (include Usbcamdi.h) |