[daala] Can I implement entropy of AV1 encoder without back-propagation of precarry buffer?

[Jarek Duda]

Hi,

I don't know the details, but might be the one to blame: sounds like an 
artifact of being able to switch between RC (range coder) and rANS 
during development (I think Alex Converse was responsible), while 
finally RC was used.

Only rANS requires buffer for backward encoding (is necessarily LIFO), 
while RC can be made both LIFO or FIFO.

Maybe they have left LIFO for this compatibility (?) - if it goes deeper 
it might need some larger rewriting ...

Best,

Jarek Duda



W dniu 27.07.2020 o 11:07, Knight Kim pisze:
> Hello,
>
> I am implementing entropy HW for AV1 video codec.
> I want to make the HW with the smallest precarry buffer.
> Currently, aom encoder is scanning reverse direction adding precarry 
> to previous buffer point.
> It means that I should keep all bitstreams in a tile, and scan all the 
> bitstreams then generate it.
> At HW point of view, this kind of operation is quite inefficient.
> Is there any way to implement the entropy encoder without precarry 
> back-propagation?
> Can I determine the maximum length of back-propagation?
>
> Thanks.
>
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-- 
dr Jarosław Duda
Institute of Computer Science and Computer Mathematics,
Jagiellonian University, Cracow, Poland
http://th.if.uj.edu.pl/~dudaj/

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