[x265] [PATCH] doc: add document that contains the reason for two versions of sao primitives

[Steve Borho]

On 04/24, Divya Manivannan wrote:
> # HG changeset patch
> # User Divya Manivannan <divya at multicorewareinc.com>
> # Date 1429865520 -19800
> #      Fri Apr 24 14:22:00 2015 +0530
> # Node ID 30217fc96291f5c3f713357a04e0759b2a44e287
> # Parent  cfc321e81396f4ad93b1bb92f786d5d233acadf8
> doc: add document that contains the reason for two versions of sao primitives

sorry, I should have been more clear. I was only asking for a comment in
primitives.h where the primitive was declared as an array[2]. It wasn't
clear there how the two were to be used.

> diff -r cfc321e81396 -r 30217fc96291 doc/sao/sao.txt
> --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
> +++ b/doc/sao/sao.txt	Fri Apr 24 14:22:00 2015 +0530
> @@ -0,0 +1,31 @@
> +***
> +SAO
> +***
> +
> +x265 has an option: '--sao' that toggle sample adaptive offset loop filtering. 
> +The following primitives in sao are changed in order to increase the performance 
> +by avx2 optimization:

Can you move this below text into primitives.h or sao.cpp?

> +SAO_E0_1
> +========
> +
> +This primitive is split into two parts: saoCuOrgE1 and saoCuOrgE1_2Rows. In avx2, 
> +32 pixels in a register can be handled, but in the case of width=16, 16 pixels need 
> +to be restored. So, in order to avoid this, two rows with 16 pixels in each can 
> +be handled at a time. There may be a case with odd height so saoCuOrgE1 is used 
> +to process single row separately.
> +
> +SAO_E0_2
> +========
> +
> +This primitive is split into two parts: saoCuOrgE2[0] and saoCuOrgE2[1]. saoCuOrgE2[0]
> +is used for width<=16 and saoCuOrgE2[1] is used for width > 16.
> +     
> +SAO_E0_3
> +========
> +
> +This primitive is split into two parts: saoCuOrgE3[0] and saoCuOrgE3[1]. Here two 
> +rows cannot be handled simultaneously since it requires a pixel from the previous 
> +row. So, saoCuOrgE3[0] is used for width<=16 and saoCuOrgE3[1] is used for width > 16.
> +
> +
> _______________________________________________
> x265-devel mailing list
> x265-devel at videolan.org
> https://mailman.videolan.org/listinfo/x265-devel

-- 
Steve Borho