[FFmpeg-devel] [PATCH] Arithmetic decoding in ALS

[Thilo Borgmann]

Am 12.01.10 20:50, schrieb Thilo Borgmann:
> Am 12.01.10 00:33, schrieb Michael Niedermayer:
>> On Mon, Jan 11, 2010 at 09:15:05PM +0100, Thilo Borgmann wrote:
>>> ...
>>
>>> +    while (cf_table[sx][(symbol + 1) << delta] > target)
>>> +        symbol++;
>>
>> this probably can be speed up by a LUT of some of the MSBs
> 
> I thought a bit about that but I'm still lacking an idea of how to
> generate suitable lookup tables.
> 
> What I've tried and benchmarked as an alternative is to use a bisection
> method to search through cf_table[sx] but its slower than the existing
> solution - most likely because the number of iterations is small enough
> in almost all cases. Iterations are less than 10 in almost all cases and
> just about 900 dezicycles are spend within this loop (~1350 using
> bisection).
> 
> So I don't know if it really needs to be optimized?
> 
> All other issued done. Revision 1 attached.

Ignore revision 1. Revision 2 attached.

-Thilo
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