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Estimate max number of FIR filter taps on BF processor, how to?

Question asked by toebs on Dec 9, 2011
Latest reply on Dec 13, 2011 by pfeifferc

Hi as your have propably already guessed from the heading, I am a digital signal processor newb.

 

I need a Black Fin, to run FIR filters for an active speaker design. It's a 2-way speaker, since i have stereo its two 2-way speakers, hence four channels.

My filter is 512 taps long, for both driver units.

 

The only thing the Black Fin is doing is:

 

Audio in from two channels (48kHz, 16bit), FIR filter, and output to the four channels.

 

I am having trouble calculating how fast a processor i need. At the moment i have implemented it on a Sharc ADSP-21369, just to verify my filter designs, but i would like to implement it on something cheaper, say a Black Fin.

 

Here i can see (page 22) that the BF504 has 800MMACs http://www.analog.com/static/imported-files/selection_tables/Embedded_Proc_DSP_Sel_Guide_2010.pdf

 

Can i some how estimate/verify if these 800MMACS, are enough to run my 4 512 tap long filters, real time, on 48kHz 16bit audio?

 

My best guess is this:

Max Number of taps = (800E6 MACs) / 48000 = 16700.

 

But this assumes that the code is somehow perfect and no resources are spend doing other than filtering, which is probably not plausible?

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