How to normalize audio input?

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fei on 24 May 2013
Answered: Antonio Ferreras on 22 Oct 2019
Hello, does anybody know how wavrecord function scales PCM format (range 0-256 or 0-65536) into -1;1 interval? many thanks for answers

Answers (3)

Daniel Shub
Daniel Shub on 24 May 2013
The wavrecord function does not do the scaling but rather the recsnd function handles the scaling. The recsnd function is/was not a well defined entity since it was a platform dependent mex file and in some cases it used audiorecorder. The wavrecord function is now obsolete and is slated to be removed, so there is no single version...
That said, (x-128)/128 is probably a reasonable approximation of the conversion. Do you have reason to doubt this?

fei on 26 May 2013
Thank you for your answer Daniel, finally I used mapminmax function which uses this algorithm: y = (ymax-ymin)*(x-xmin)/(xmax-xmin) + ymin;
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Jan on 26 May 2013
Please post comments in the comment section of the corresponding answer, not as further answer. Thanks.

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Antonio Ferreras
Antonio Ferreras on 22 Oct 2019
The problem con mapminmax is that it introduces a continuus bias


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