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Audio drop-outs when playing AAC files on Sansa E260 (Nero codec)

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saratoga:

--- Quote from: OldSchool on January 07, 2008, 09:55:47 PM ---Actually, fixed point filter design and implementation is generally considered (so I'm told, I've never done it either) to be much more difficult because of arithmetic over/under flow, saturation, quantization noise, scaling etc etc. As it turns out, I do have access to some design tools (and I'll try your suggestion about wmsfixed.c/h - thanks), so there's still hope...

Cheers.

--- End quote ---

I don't think thats going to be a real issue here.  You're not building high order filters and you don't care about quantization error since your display will only have a handful of levels.  I think this application will be more tolerant then what most people need to design for, so you'll be able to get away with a lot more.

OldSchool:
I did some fiddling with the filter designer (Matlab) and, if I start with 7 bands, centred on 40, 150, 400, 1K, 2.4K, 6K and 12.5 KHz (numbers from an old JVC cassette deck), I can use one low pass, one high pass and five band pass IIR filters.

Using elliptical filters with 1dB passband ripple, about 30 down in the stop bands, I can get what looks like fairly good roll-off with 6th order bandpass and 3rd order high/lowpass filters.

Anyway, that'll be my starting point. Next I'll try the fixed point conversion process on   the filters and see where that leads. If nothing else, I'll at least I'm learning the design tools. :)

If anyone is still following this thread, I'd be interested in comments/suggestions.

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