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About UVC bulk transfer RRS feed

  • Question

  • HI,

    I am developing a UVC client driver and this is using USB bulk end point to transfer the video data and Maximum packet size if 512 bytes. when the device is connected to host PC device enumeration is successful and UVC driver is receiveing cable attached message, and driver received video streaming requests.

    when driver received SET_CUR of commit control, I start transfering the data by calling lpIssueTransfer function.

    Video frame size is 640 x 480 and in each IssueTransfer i am sending 512 bytes.

    On host side I opened AmCap application, it was not showing any error messages but showing whole preview as black. I captured usb packets using USB Trace application and noticed that data is transfered to the host but there is no preview available on Amcap application.

    Can any body help on this??

    Thanks

    Subbarao.

    Tuesday, June 8, 2010 7:18 AM

Answers

  • UVC working on bulk endpoint, we found the mistake in our driver. previously we wrongly configured the payload header. so we corrected the pay load header and it is working.

    So usbvideo.sys is supproting bulk and isochronous transfers for video preview.

    Thanks

    Subbarao.

    • Proposed as answer by Vinoth[MCTS] Saturday, June 12, 2010 1:40 PM
    • Marked as answer by Subbarao. _ Saturday, June 12, 2010 1:41 PM
    Saturday, June 12, 2010 1:02 PM

All replies

  • Have you tried Isochronous?
    As my understanding, the Bulk mode in UVC is mostly used in Still Image Capture scenario, Preview and Motion Cature usually use Iso transffer.
    Maybe the AmCap orWindows UVC driver does not support Bulk for preview.
    Tuesday, June 8, 2010 8:15 AM
  • Thanks for your reply,

    As my developing platform does not support isochronus transfer mode, i am using bulk transfer mode.

    Windows UVC host driver (usbvideo.sys) will support the bulk and isochronous modes.

    You can check this link : http://support.microsoft.com/kb/828756/en-us

    Thanks,

    Subbarao

    Tuesday, June 8, 2010 10:22 AM
  • Yes, the page mentions about support bulk/Iso transfer but it doesn't mention if it supports using Bulk for Preview.
    Anyway, here is another thing you can try.
    Since you have USB analyzer on hand, why not plug in a regular USB camera and observe how camera communicate with PC during preview?
    Sometimes it is the configuration parameters (Endpoint/interface descriptor) that causes driver malfunctions.

    Tuesday, June 8, 2010 11:31 PM
  • UVC working on bulk endpoint, we found the mistake in our driver. previously we wrongly configured the payload header. so we corrected the pay load header and it is working.

    So usbvideo.sys is supproting bulk and isochronous transfers for video preview.

    Thanks

    Subbarao.

    • Proposed as answer by Vinoth[MCTS] Saturday, June 12, 2010 1:40 PM
    • Marked as answer by Subbarao. _ Saturday, June 12, 2010 1:41 PM
    Saturday, June 12, 2010 1:02 PM
  • Hi Subbarao:

    i have some problem about UVC bulk transfer in windows(device side)!!

    can you provide some information to me!!

    i decribe my situation :

    1. enumeration is proper(bulk transfer, max packet size is 512)

    2. after open amcap, can receive host probe & commit control(max payload size is 512)

    3. but i can't see any in token in bulk pipe, but ican see interrupt in token

    4. how to send stream to host??  device need to send stream actively??

    thanks!!

    polo.

     

    Monday, March 28, 2011 7:24 AM
  • Hi Polo,

    With successful commit control, device will receive SET_CUR, then device can start sending the UVC data by calling "lpIssueTransfer" function.

    Thanks,

    Subbarao.

    Tuesday, March 29, 2011 11:41 AM
  • Hi Subbarao:

    I encounter some situations as Polo.

    Is "IpIssueTransfer" function not standard UVC command,and do we need write another driver for this device?

    I may need to use bulk transfer by standard UVC 1.1 without writing another driver for this device. 

     



    Thanks!!

    alucardwang1



    Monday, April 11, 2011 2:50 AM