[sdiy] resampling wav files

Richie Burnett rburnett at richieburnett.co.uk
Thu Apr 19 20:39:06 CEST 2018


Thanks Eric. I didn't know it had this built-in function. I'll give it a try on MATLAB tomorrow at work :-)

Sent from my Xperia SP on O2

---- Eric Brombaugh wrote ----

>Richie,
>
>Matlab & Octave have a variety of different ways to do interpolation / 
>decimation. The resample() function that I suggested does rational 
>resampling - the p & q arguments tell the upsampling and downsampling 
>rates with a lowpass antialias FIR filter that's tailored to the p & q 
>requirements. There are optional arguments that allow further refinement 
>of the filter characteristics, but with the simplest call it's pretty 
>close to an optimum sinc interpolation.
>
>Eric
>
>On 04/19/2018 11:18 AM, Richie Burnett wrote:
>> Eric, What resampling method does octave  use internally? Sinc? Linear interpolation? Etc...
>> 
>> ---- Eric Brombaugh wrote ----
>> 
>>> Install a copy of Gnu Octave:
>>>
>>> https://www.gnu.org/software/octave/
>>>
>>> Write a quick script to read a .wav file, resample and write it out. Use
>>> these functions:
>>>
>>> y = wavread (filename)
>>>
>>> [y, h] = resample (x, p, q)
>>>
>>> wavwrite (y, filename)
>>>
>>> Done.
>>>
>>>
>>>
>>> On 04/19/2018 10:29 AM, Tim Ressel wrote:
>>>> Hi,
>>>>
>>>> Looks like there's some DSP in my future. I need to resample wave files
>>>> to get them from 600 samples down to 256 samples. Unless there is a
>>>> groovy toll out there that can do that, I gotta write an app for it. As
>>>> far as I can tell I need to interpolate 32x and then decimate 75x, with
>>>> all the attendant filters that these processes need. I know just enough
>>>> DSP to be dangerous.
>>>>
>>>> Thoughts?
>>>>
>>>
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>




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