Davinci Resizer coefficients

Syed Mohammed, Khasim khasim at ti.com
Wed Sep 10 09:40:49 CDT 2008

Hi Rafael

> -----Original Message-----
> From: davinci-linux-open-source-bounces at linux.davincidsp.com [mailto:davinci-linux-open-source-
> bounces at linux.davincidsp.com] On Behalf Of Rafaël Carré
> Sent: Tuesday, September 09, 2008 4:41 PM
> To: Jon Povey
> Cc: Davinci-linux-open-source at linux.davincidsp.com
> Subject: RE: Davinci Resizer coefficients
> On Tue, 2008-09-09 at 11:56 +0100, Jon Povey wrote:
> > This is not my area, just trying to understand and be another pair of eyes:
> >
> > As I see it you would supply an intended ow (you have a target output size in mind) and use the
> first function to calculate hrsz. Because of the floor() you may not get the exact ow you wanted, you
> can use the second function to work out what ow you really get. You can try adding 1 to hrsz and see
> what ow that gives you, if that is any better.

I was having similar discussion with Xiangdong, Here is what he advice me,
The steps are clearly outlined in spraai7 (http://focus.ti.com/lit/an/spraai7b/spraai7b.pdf ). Basically, one starts with iw and ow, which are your input and output widths, respectively, and gets the hrsz. Once this is done, use the second equation to recalculate the ow. Now you have all iw, ow and rsz values that can be programmed to the resizer. No more iterations are needed there.

Hope this is helpful.


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