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Video Capture — Parallax Forums

Video Capture

pbhuterpbhuter Posts: 36
edited 2010-08-05 13:44 in Propeller 1
I know the Propeller chip can generate video, but can it capture it? If so, how does one go about doing it? Thanks.

Comments

  • LeonLeon Posts: 7,620
    edited 2010-08-05 12:26
    It just isn't fast enough, and doesn't have enough memory, for real-time video capture. I'd use something like the ADI Blackfin.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 12:31
    I should have been more specific with what I want to do. I don't want to actually capture and process video so much as single still images and then compare those images to other images. Am I still out of luck?
  • LeonLeon Posts: 7,620
    edited 2010-08-05 12:37
    You can do that with a suitable ADC. I think that someone already has a design and software for it.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 12:53
    By "ADC" do you mean analog to digital converter? If so, I'm doing a search in the Object Exchange and not really coming up with anything that will allow me to capture a single image from a camera. I see a lot of things that indicate that I would need another ADC chip, which is fine, but a lot of what I see in the OE and on the Parallax product page talk about voltage conversion, so I'm not really sure how to go about doing this. If you haven't figured it out yet, I really don't know what I'm doing, just what I want to do, so any help would be appreciated. Thanks.
  • LeonLeon Posts: 7,620
    edited 2010-08-05 13:04
    Yes, you use an analogue-to-digital converter. It doesn't have to be all that fast. The way you do it is to digitise the image a line at a time, on consecutive frames. It's called a "frame-grabber":

    en.wikipedia.org/wiki/Frame_grabber

    I found this with a search of the forum:

    http://forums.parallax.com/showthread.php?p=686552

    There are others, probably.

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    Leon Heller
    Amateur radio callsign: G1HSM

    Post Edited (Leon) : 8/5/2010 1:11:37 PM GMT
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 13:10
    Great! I will look into frame-grabbers some more. Thank you for all your help Leon.
  • LeonLeon Posts: 7,620
    edited 2010-08-05 13:15
    I knew how they worked, but I couldn't remember what they were called. I searched for video and ADC and it came up immediately.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 13:24
    I found another post that talks about doing exactly what I want to do. Told me to buy a book, which I just ordered (it has more stuff than I need, but at least will get me started). Thanks again for your help.
  • RaymanRayman Posts: 15,009
    edited 2010-08-05 13:35
    Well, you can capture very low quality b&w video with just resistors, capacitors, and a diode or two...

    Search for "Stupid Video Capture"...

    I did it myself and posted "Stupider Video Capture"...

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    My Prop Apps:· http://www.rayslogic.com/propeller/Programming/Programming.htm

    My Prop Info: ·http://www.rayslogic.com/propeller/propeller.htm
    My Prop Products:· http://www.rayslogic.com/Propeller/Products/Products.htm
  • legoman132legoman132 Posts: 87
    edited 2010-08-05 13:37
    In the ROBOT magazine article about viewport, it talks about using an "ADC08100 A/D" to capture video

    www.parallax.com/Portals/0/Downloads/docs/article/ROBOT_ViewPort.pdf
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 13:40
    I was looking into ViewPort, but I'm not sure if it will allow me to do the video capture/processing on the Propeller board, or if I need it to be connected to a computer. I'll continue to research it, though. Thanks.
  • legoman132legoman132 Posts: 87
    edited 2010-08-05 13:42
    It looks like you would need a computer connected, but looking at the demo code may help
  • pbhuterpbhuter Posts: 36
    edited 2010-08-05 13:44
    Okay. I think I may have found some ways to do on-board processing...researching it further.
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