[maemo-developers] Signal processing on N800

[From: Sarah Newman]

Do you think that is significantly more efficient than kiss fft?  We 
have been considering using FFTs optimized for arm but platform 
independence is always nice.

David Huggins-Daines wrote:
> On Wed, 2008-04-23 at 14:15 -0500, nisha jain wrote:
> 
>> to port it to N800 later on...Please let me know if some one has
>> developed such 
>> application and used fft calculation for discrete signals... 
> 
> If you are dealing with real-valued data (e.g. audio), you can use the
> fixed-point FFT routine in CMU Sphinx if you like.  It's not
> specifically optimized for the ARM but it's pretty fast.  Browse the
> code at:
> 
> http://cmusphinx.svn.sourceforge.net/viewvc/cmusphinx/trunk/sphinxbase/src/libsphinxbase/fe/fe_sigproc.c?view=markup
> 
> The functions you need are fe_create_twiddle() and fe_fft_real().  They
> come in 16 and 32-bit versions, based on the FIXED16 preprocessor
> symbol.  The 32-bit version is a bit confusing since it uses 20.12
> fixed-point format, so I'd recommend the 16-bit one (which is faster
> anyway).
> 
> You'll have to do a bit of work to separate it from the rest of the
> front end processing, but that shouldn't be hard.
> 
> Better would be to use TI's dsplib on the DSP core, but I still haven't
> gotten around to figuring that out.
> 
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