[FFmpeg-devel] a64 encoder

Bitbreaker/METALVOTZE bitbreaker
Sat Jan 17 16:52:00 CET 2009

> reducing the colors before seems quite suboptimal, id rather convert each
> fullcolor "char" with dithering to what is available afterwards or even
> during the elbg code.
I have tried converting to a charset beforehand already some time ago, 
it can lead to other problems therefore, depending on what area i 
calculate the error. If i do a pixelwise compare, i gotta stick to the 
ditherpatterns or error goes up.

Imagine the following two chars: visually both the same. but if 
pixelwise compared, they differi quite alot:

01010101    10101010
10101010    01010101
01010101    10101010
10101010    01010101

If i compare on my meta basis or in RGB/whatsover, the algorithm finds 
this both chars are identic.

That was, why i decided to first find the best blocks and then render 
the (dithered) charset. If i really happen to get two identic chars in 
the end, it doesn't matter too much, as it seems all other replacemenst 
so far didn't bring in much error by then. Practically from what i have 
seen from my both attempts however, i'd say i can't see any difference 
between both methods :-)  In that case i  should be happy if i can use 
the elbg code as is, furthermore it is enough doing so only on the 
lumincnace channel.
But well, stay tuned until i've tested and get first results (speed, and 
a picture to see) and we'll see :-)

Kindst regards,


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