[Mp4-tech] question ME algorithm

[Wang Hui]

Dear Allen¡G
Thank you for your email.
I understood what you said, 
Sometime when the sequence with low motion, the FS maybe the worst one.I think Whether need to modify the PSNR computing method, in order to keep the criterion consistent.When FS is worst, how to know that the algorithm implementation is wrong or duing to PSNR computing?
best regards
Michael
----- Original Message ----- 
From: "Allen H.-Y. Chin" <hychin swallow.ee.nctu.edu.tw>
To: "Wang Hui" <wangh china.com>
Cc: "MP4-Tech" <MP4-Tech lists.mpegif.org>
Sent: Monday, December 08, 2023 7:49 PM
Subject: Re: [Mp4-tech] question ME algorithm
> Michael,
> 
> Sometimes I get slightly better PSNR results by switching to fast ME
> algorithm in MPEG-4 VM.
> 
> In VM18 by microsoft, the matching criterion for ME is SAD (sum of
> absolute difference).
> However, SSD (sum of square difference) is used in computing PSNR.
> Thus, a best-matched reference block found by ME using SAD does not
> guarantee minimum PSNR.
> 
> e.g.
> 5+6 > 1+9
> 5^2 + 6^2 < 1^2 + 9^2
> 
> Regards,
> Allen
>