[FFmpeg-devel] pre discussion around Blackfin dct_quantize_bfin routine

Marc Hoffman mmh
Wed Jun 13 02:14:53 CEST 2007

On Jun 12, 2007, at 7:27 PM, Michael Niedermayer wrote:

> Hi
> On Tue, Jun 12, 2007 at 02:52:29PM +0300, Siarhei Siamashka wrote:
>> On 6/12/07, Michael Niedermayer <michaelni at gmx.at> wrote:
>>> Hi
>>> On Tue, Jun 12, 2007 at 05:49:19AM -0400, Marc Hoffman wrote:
>>>> Does these allow me to ignore the DCT permutation?
>>> no it would still break if the user selected the other integer idct
>> Is it possible to add a configure option to be able to compile ffmpeg
>> only with IDCT that do not need permutation (and do not allow the  
>> user
>> to select other idct)? At least it would eliminate table lookups in
>> many places (replace table lookups with a macro which expands either
>> to table lookup or the value itself). The point is that ARM devices
>> are heavily CPU limited and ARMv5TE optimized IDCT does not use
>> permutation. Blackfin powered devices may be CPU limited too (Marc  
>> can
>> probably privide more information about blackfin performance). I'll
>> try to do some benchmarks on ARM and post some results later.
> if(idct_permutation_type != FF_NO_IDCT_PERM)
> is fast, there is no need to randomly hack up the code

Agreed this makes complete sense.


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