Audio recording / playback with the Propeller

Ken Peterson

I'm working on a project that involves recording and playing back audio in the 4kHz range (voice only).· I'm pretty familiar with the delta-sigma A/D and I've already used it for other things.· I have also written a short program to record 3 seconds of speech and play it back using HUB memory to store the audio samples (8kHz rate, 8-bit samples, uncompressed) and the built-in mic on the Demo board.

I'm just wondering if anyone has done work in the area of recording human speech with the Propeller that they're willing to share.· I would like to be able to record much more than 3 seconds as well as do multiple recordings.· I'm only asking this because I·don't have much time to devote to it and I'd rather·not·spend time doing things that others·have done and are willing to share.· Plus, I might learn something!· Perhaps someone has written some·speech-quality compression algorithms that would work on the Prop?

Or, if I'm breaking new ground here, I will try to post anything I come up with that may be useful.· However, don't get your hopes up.···

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The more I know, the more I know I don't know.· Is this what they call Wisdom?

Beau Schwabe

Ken,

have a look at this thread...
http://forums.parallax.com/forums/default.aspx?f=25&m=217193

...you should easily be able to modify the code so that it records and stops, or whatever you want it to do, without the Echo effect.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

hippy

I played with Rayman's WAV player ( 8kHz ) taking every other sample ( 4kHz ) and filling in the missing with a simple (last+this)/2 and it didn't sound too bad. 5 x 6-bit samples per long would give you another 25%; 9 seconds total. No code, just throwing ideas in the air.

Fred Hawkins

Hippy's slight of hand reminds me of TI's Linear Predictive algorithm, without the Predictive. (They were synthesizing though.)