Brightness control from UVC endpoint

[Bariel76]

Hi All,

It is my first time with a UVC endpoint. I read a lot on the protocol in the last days. But I still have problem using the options of the processing unit descriptors.

Here is a little context:

I merged the "evkmimxrt1060_dev_video_virtual_camera_bm" demo project with the "evkmimxrt1060_csi_raw8" project. 

I am able to get a video feed in RGB565 format from the MT9M114 camera. I use opencv2 in python to get the feed.

I am using the UVC class version 1.1.

Here is the problem:

I set the processing descriptors to unable the brightness control

    /* Processing Unit Descriptor start*/
    USB_VIDEO_VIRTUAL_CAMERA_VC_PROCESSING_UNIT_LENGTH, /* Size of this descriptor, 10+n */
    USB_DESCRIPTOR_TYPE_VIDEO_CS_INTERFACE,             /* CS_INTERFACE, descriptor type */
    USB_DESCRIPTOR_SUBTYPE_VIDEO_VC_PROCESSING_UNIT,    /* VC_PROCESSING_UNIT, descriptor subtype */
    USB_VIDEO_VIRTUAL_CAMERA_VC_PROCESSING_UNIT_ID,     /* A non-zero constant that uniquely identifies the
                                                           Terminal within the video function. This value is
                                                           used in all requests to address this Terminal. */
    USB_VIDEO_VIRTUAL_CAMERA_VC_INPUT_TERMINAL_ID,      /* ID of the Unit or Terminal to which this Terminal is
                                                           connected */
    0x00U, 0x00U, /* This field indicates the maximum digital magnification, multiplied by 100U */
    0x02U,        /* Size of the bmControls field, in bytes: n */
    0x00U, 0x01U, /* Brigthness control */

    0x00U, /* A bitmap of all analog video standards supported by the Processing Unit */

 However, when I send the following, there is not breakpoint I can place anywhere that will get triggered. 

cap = cv2.VideoCapture(1)
exposure = cap.set(cv2.CAP_PROP_BRIGHTNESS, 0.1)

 Any ideas on how to make this work?

[Bariel76]

Ok, I have found the function in usb_device_video.c. 

USB_DeviceVideoVcProcessingUnitRequest

However, the openCV command below does not trigger the function. Does openCV need UVC version 1.5 in order to work? What am I missing?

exposure = cap.set(cv2.CAP_PROP_BRIGHTNESS, 1)

[nxf77486]

Hello,

Thank you for contacting NXP support.

We have the following application note that explain how to implement and use an UVC device on the RT. I think this could be helpful as a guide for your project.

Please let me know if there is anything else where I can help you.