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USB Camera Issues RRS feed

  • Question

  • Hi,

    HW: AM335x Processor, No HW Codecs

    OS: Compact 7

    Thread Priorities: USB Controller Thread (90), USB Camera Driver (capture thread, fill thread) = (120, 110).

    Observations:

    1. When we plug a USB Camera for most of the times the following message is displayed = WARNING: MDD did not provide buffer in time for capture, dropped frame fff
    2. Also in the DDrawtest app the frame is shown only when we remove the USB Camera from the port.

    How to prevent MDD did not provide buffer issue?

    Regards,

    GSR



    • Edited by GSRid Friday, May 8, 2015 5:29 AM
    Friday, May 8, 2015 5:29 AM

All replies

  • Hi ,

    I am able to see the frames by increasing the Capture thread priority and Fill thread priority to 80 & 70.

    But, in the App we see frame in half of the screen. What could be the issue?

    Regards,

    GSR

    Friday, May 8, 2015 5:50 AM
  • That might be an image codec issue. Do you have all of the codecs you need for your camera installed? Take a look at the req's for econ system's USB camera as that might help.

    http://www.e-consystems.com/blog/windowsce/?p=628

    Tuesday, May 12, 2015 10:26 PM
    Moderator
  • Hi,

    What is the image format(YUV or MJPEG) you are trying currently?

    What is the resolution you are using in your app?


    Please mark it as answer or vote as helpful if my reply helps.

    Regards,

    Prabu[eMVP]

    http://prabukumar.wordpress.com

    Wednesday, June 10, 2015 3:27 AM
  • Hi,

    • We are using YUV (UncompressedSupport is set to 1)
    • We tried different resolutions 160 x 120; 176 x 144; 320 x 240 and 640 x 480.

    I restored the thread priorities to 110 and 120.

    Now, we are able to see frames on display but frame rate is very slow(1 or 2 FPS).

    We see the following message continuously: WARNING: MDD did not provide buffer in time for capture, dropped frame

    Regards,

    GSR

    Monday, June 15, 2015 7:50 AM
  • Do you get this warning even in the lower resolution like 160x120,because this occurs when your CPU speed is not enough to do the YUV frame rendering.

    It looks like your DirectShow rendering is taking too much of time to process the YUV frames.Did you tried to render any video on to the screen from the media file?


    Please mark it as answer or vote as helpful if my reply helps.

    Regards,

    Prabu[eMVP]

    http://prabukumar.wordpress.com

    Tuesday, June 16, 2015 2:34 PM
  • Hi Prabhu,

    Thank you for your time and reply.

    Yes we are seeing the issue even for the lower resolutions.

    Ok, I will try a video from Video Player.

    Just, I have one doubt USB Camera uses Isochronous transfers. So, there is a chance of loosing frames by the Host Controller.

    Lets's say when the resolution is 176x144 with 16 Bits per pixel to take one picture we need a complete frame data of size 50688. But, with isochronous if we miss some packets in a frame how can we construct one snapshot?

    Any suggestions on this?

    Regards,

    GSR


    • Edited by GSRid Friday, June 19, 2015 6:19 AM
    Tuesday, June 16, 2015 6:32 PM
  • Hi,

    When we play wildlife.wmv video file the video runs at very slow.

    Are there any tools to calculate what is the frame rate that the current video is playing in Windows CE?

    Regards,

    GSR

    Friday, June 19, 2015 6:19 AM
  • So it looks like there is an issue with your display driver of your platform.Because of it only you are seeing very slow rendering.If the static video play fine then the camera application will also work fine.

    Check with your platform vendor for the display driver lag.


    Please mark it as answer or vote as helpful if my reply helps.

    Regards,

    Prabu[eMVP]

    http://prabukumar.wordpress.com

    Tuesday, June 23, 2015 7:15 AM