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Square Pixels - Which Video Decoder to Use?

Al Testani
Prodigy 30 points
Other Parts Discussed in Thread: TVP5150AM1, TVP5150

We need an analog video converter to do NTSC/PAL at a minimum, but support for component video would be good.  We need to output square pixels (preferably @ 640 x 480). Switching different pixel clocks is not a problem if it is necessary.  

I have been searching for a long time I am finding this to be difficult to sort out and could use some help.  I can find some parts that are NRND that can do what we need and I understand there are others that can do it with a patch.  I find some of the NRND parts are still being recommended in this forum as late as last month.  I also find parts e.g. 5150 that is active and there may be a patch to allow it to do square pixels.  

So my question is  what are the Active and NRND parts that can do square pixels and what patch do I need, if any?  

Thanks 

Al Testani

  • 0
    TI__Mastermind 43875 points
    Al,
    ALL the TVP devices except the TVP5150AM1 are now NRND.

    The 'recommendations' in the forum are merely suggestions and not really 'recommendations' as such. The NRND devices are not recommended simply due to design in support availability (or lack of). They will still be available for purchase for the foreseeable future but we will not be able to help with issues that might arise during product development.

    Whether patch is required or not does not change the device NRND status unfortunately.

    The device patch information can be found here...
    software-dl.ti.com/.../Analog_Video_Decoder_Versions.htm

    Hope this helps.

    BR,
    Steve
  • 0 in reply to Steve Clynes
    Prodigy 30 points

    I did a reply yesterday but it has vanished...

    In any case, thanks for the information, Steve.  The patch list was very useful as I see there is a square pixel patch for the TVP5150.  A couple of questions:

    1. Is there any more documentation on how to use the patched part?  I can see how to put it in SQP mode but can't tell what the pixel/line counts are for the various input formats.  Can I change these?  I need to scale to get to 640x480 for NTSC and PAL but can throw away a few lines for PAL.  

    2. How to apply/select sampling clocks is another question.  I see the MHz values in the patch release notes but are these input to the part where the 14.318MHz crystal normally connects?.

    3. Is their a price tier or different part number to use to get the part with the patch already applied? 

    Thanks

    Al

  • 0 in reply to Al Testani
    TI__Mastermind 43875 points

    Al,

    1) The documentation on how to use the patch should be included in the patch download. I believe square pixel will output 640 pixels per line, which is how the pixels is effectively sampled as 'square'. The only way you can 'scale' the image is to crop it. The scaling is effectively done by switching the sampling points in the analog signal. Don't forget that in analog video there is not really a discrete 'pixel' horizontally.

    2) The sampling clock will be automatically derived from the reference clock source. An internal PLL will lock to the horizontal sync pulses and generate the correct number of output samples per line. All you need to do is make sure the reference clock is correct for the particular device/patch.You cannot, for example, provide a direct sampling clock of say 27MHz to the input since the internal PLL expects a very specific reference frequency then it generates the true sampling clock with the correct phase alignment.

    3) Patch is code that you must load to the video decoder every time it is powered up. There are not different part numbers since the patch is software. The patch code release notes should explain the procedure to load the patch code at chip power up.


    BR,

    Steve

  • 0 in reply to Steve Clynes
    Prodigy 30 points
    How can I get verification on the 640 active pixels/line? This is a key requirement. It would also be useful to know the total number of pixels/line and lines/frame.

    In terms of the clock: so we would still use a 14.31818MHz crystal and the patch takes care of setting up the current sampling frequencies?