GET_INFO request shall report such control as an Autoupdate Control (for example, D3 bit shall be set to 1) but not as an Asynchronous control (for example, D4 bit shall be set to 0).įor such control, a SET_CUR request can be issued to set a new value (a SET_CUR(NORMAL) request wherein bmOperationFlags:D0 bit is set to 0) or cancel a previous SET_CUR(NORMAL) request (a SET_CUR(CANCEL) request wherein bmOperationFlags:D0 bit is set to 1). The following table maps the control selectors for Microsoft-XU to their respective values and the bit position for the bmControls field in Extension Unit Descriptor:Ī Cancelable control is defined here by leveraging the Autoupdate capability. All other fields shall be set to 0.Ī SET_CUR request is issued by host after setting all fields. GET_DEF and GET_CUR requests shall report the default and current settings respectively for the fields qwValue/dwValue and bmControlFlags. In addition, all supported flags shall be set to 1 in bmControlFlags. GET_MAX request shall report the maximum supported value for qwValue/dwValue. GET_MIN request shall report the minimum supported value for qwValue/dwValue. GET_RES request shall report the resolution (step-size) for qwValue/dwValue. GET_LEN request shall report the maximum length of the payload for this control ( wLength). GET_INFO request shall report the control without AutoUpdate and Asynchronous capabilities (for example, D3 and D4 bits shall be set to 0). Refer to UVC 1.5 Class specification.pdf for definitions of D3, D4, GET_INFO, and so on. The following request definitions apply to all these controls unless an overriding definition is specified explicitly for that control. Ġxf3f95dc, 0x2632, 0x4c4e, 0x92, 0xc9, 0xa0, 0x47, 0x82, 0xf4, 0x3b, 0xc8) Ī Microsoft-XU implemented by the device firmware will house the new controls defined in the following sub-sections. Microsoft's extension to the USB Video Class specification for enabling new controls is done through an extension unit identified by GUID MS_CAMERA_CONTROL_XU (referred to as Microsoft-XU). When this entry is set to Enabled (0x1), the capture pipeline will leverage Method 2 for Still Image Capture (assuming the firmware also advertises support for Method 2 as specified by UVC 1.5 spec).Īn example for the custom INF section would be as follows: ĪddInterface=%KSCATEGORY_CAPTURE%,GLOBAL,USBVideo.InterfaceĪddInterface=%KSCATEGORY_RENDER%,GLOBAL,USBVideo.InterfaceĪddInterface=%KSCATEGORY_VIDEO%,GLOBAL,USBVideo.InterfaceĪddInterface=%KSCATEGORY_RENDER_EXT%,GLOBAL,USBVideo.InterfaceĪddInterface=%KSCATEGORY_VIDEO_CAMERA%,GLOBAL,USBVideo.Interface The custom INF file, based on either custom UVC driver or inbox UVC driver, should include the following AddReg entry:ĮnableDependentStillPinCapture: REG_DWORD: 0x0 (Disabled) to 0x1 (Enabled) Note: The camera driver can be based on the Windows USBVIDEO.SYS or can be based on a custom driver binary. In Windows 10, version 1703, devices that leverage this method must use a custom INF file for the camera driver, but a custom INF is required for the given hardware to enable Method 2 still image capture). In Windows 10, version 1607 and earlier, the capture pipeline did not leverage Method 2, even if a device advertised support for it per the UVC 1.5 spec. Some existing UVC devices may not support Method 2 described in section 2.4.2.4 (Still Image Capture) of the UVC 1.5 Class specification.pdf that can be downloaded at the USB Video Class specification web site. 2 Architectural Overview 2.1 Description 2.2.1 Capability discovery through INF 2.2.1.1 Still Image Capture – Method 2 VRAM or DX surfaces will not be supported. UVC metadata will only support system allocated memory. Every IHV/OEM that needs metadata support must enable this through a custom INF file. UVC metadata support will be available only through the Media Foundation (MF) capture pipeline. UVC metadata support will be only available to frame based payloads. However, in the case of BULK endpoint, the metadata size will be limited to 240 bytes (due to the fact that all video frame data is transferred in a single video frame packet on BULK endpoints). The USB Video Class (UVC) frame metadata support will be available to ISOCH and BULK endpoints. Microsoft extensions to the USB Video Class specification enable new controls as well as the capability to carry well-defined frame-metadata in a standard format.
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