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Simple and available video decoders?

Discussion in 'Electronic Basics' started by ErikBaluba, Feb 27, 2006.

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  1. ErikBaluba

    ErikBaluba Guest

    Hi,

    I want to develop my own video grabber, for some experimentation with video
    image processing. I wonder if there is a preferred video decoder often used
    in hobbist like projects?

    I looked up some available analog video decoders, like the Texas Instruments
    TVP5150A, which seems quite easy to use. However they all seem to output
    only YCrCb, the TVP5150 no different outputting 8-bit ITU-R B.656. I need a
    chip that can also output raw RGB, since I assume that is what I need in my
    VRAM bank for simple edge detection and object tracking capabilities.

    Any suggestions appreciated.

    erik
     
  2. Deefoo

    Deefoo Guest

    I was going to suggest the Brooktree BT478 but I am not sure if it is still
    around. It is (was) used on many cheap PC TV add-on cards.

    Anyways, you don't need RGB for edge detection. Edge detection can be done
    in any color space, although some color spaces may be more suitable for the
    kind of features you are looking for. Grayscale may even be sufficient.
    Furthermore you can convert between color spaces in software. Google for YUV
    to RGB or RGB to YUV.

    --DF
     
  3. Deefoo

    Deefoo Guest

  4. tlbs

    tlbs Guest

    I just finished an NTSC to RGB project last year. I could not find a
    single-chip solution. I used a double-chip solution -- Analog Devices
    ADV7181 coupled to an ADV7179. They work very well.

    Good luck,
    Tom
     
  5. ErikBaluba

    ErikBaluba Guest

    ....
    The 7181 outputs 8-bit YCrCb . Did you convert to RGB in software?

    The 7189 is an encoder, did you need that in your setup?
     
  6. tlbs

    tlbs Guest

    ...
    We used the 7181 to digitize the NTSC video, then we fed the YCrCb to
    the 7181 to convert it to individual RGB analog outputs. The 8-bit
    YCrCb was routed through an FPGA, but that is for future expansion.
    Right now, the digitized video just passes straight through the FPGA
    (with a single pipeline delay; i.e. one flip-flop/register). The FPGA
    also handes the I2C interface to the video chips, for setup.

    The YCrCb and clock outputs of the 7181 can be connected straight to
    the 7179. They are designed to work together. The default settings
    may be sufficient for your application, so you wouldn't need to have an
    I2C interface -- just a reset signal.

    Analog devices also sells other decoder/encoder chip *pairs* in the
    same family. Check out www.analog.com.

    BTW, I am not an Analog Devices employee or salesman -- I just happen
    to like some of their product lines.

    Tom
     
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