ADV7183 and QVGA (320*240 pixels)

Hello,

I have a product setup to capture VGA size images (720*480 pixels) from ADV7183 in CCIR format. My target DSP is a bf548. It is all working well and great with help of using diverse application notes and examples. My circuit is a true copy of ezkit bf548 attached to A-V EZ-Extender card.

Now I want to be able to get QVGA (320*240 pixels) instead. I can see that this is possible using e.g. uclinux distribution running ffmpeg etc. What I cannot find any information about is how is QVGA created using the ADV7183. Can the ADV7183 be setup to deliver QVGA images instead of VGA images or is it simply a QVGA window in the full VGA image received on the PPI port, or is it a scaling routine in the DSP down sampling the image to QVGA?

No matter how it is done, could any one provide me with input to re-configure my system to capture/treat QVGA instead of VGA?

Best Regards,
Kim.

  • 0
    •  Analog Employees 
    on Feb 24, 2012 10:13 PM over 9 years ago

    Hello Kim,

    Do you mean ADV7183B? It's only a video decoder-- it can't generate anything but NTSC/PAL/SECAM formats. I would guess the DSP is merging two fields to get you 720x480 since NTSC would be 720x240 per field.

    You would need to grab a QVGA windows on the regular 720x480 since the ADV7183 can't only capture it.

    Dave

  • Hello Dave,

    Thanks. Do ADI have a video decoder chip that can deliver/scale QVGA as I now have found out that ADV7183 is obsolete?
    Do you know about any one that has made a routine in C/asm that can down scale VGA to QVGA?


    Best Regards,
    Kim.

  • 0
    •  Analog Employees 
    on Feb 28, 2012 8:30 PM over 9 years ago

    Hi Kim,

    I'm not aware of a decoder from any company that includes a scaler.  We have a shipping scaler ADV8002 that could be mated to one of our video decoders that would do that but it would be overkill for VGA to QVGA unless you wanted really good quality.

    Using a CPU/DSP and dumping every other pixel and every other line would be the cheapest way to downscale from VGA to QVGA.  Since decoders don't do VGA-- they do NTSC / PAL which is already halfway there (720 x 240) I would think that whatever you are connecting the decoder to can do it if it's converting NTSC to VGA already.


    Dave