[SciPy-User] butterworth filter on .WAV file

[Benjamin Root]

Well, to give you hope, it is feasible as some friends of mine did a notch
filter on some .wav files at the conference last week.  They had a bunch of
issues as well.  I will see if he is actively reading this list.

Ben Root

On Wed, Jul 7, 2010 at 4:55 PM, Joshua Holbrook <josh.holbrook at gmail.com>wrote:

> On Wed, Jul 7, 2010 at 1:34 PM, Peter Howard <peterhoward42 at gmail.com>
> wrote:
> > I forgot to mention that part - it plays without complaint in Window's
> Media
> > Player - but is completely silent.
> > Would it help if I provide the input .WAV file?
> > Can you attach things to posts via email?
> > (It is 13MB)
> >
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> >
> >
>
> That's huge! Nevermind that.
>
> Interestingly enough, I tried messing with the problem using a random
> wav file I found from the internet (that plays in vlc just fine) and
> got an ugly error. So, I guess I can't help you in this way :S
>
> That said, here's what I would do: First, plot the array that results
> from reading the wav file to get an idea of what it looks like. Then,
> after you butterworth it up, plot the result of THAT to see what you
> have. That could give you an idea as to whether the problem is in the
> reading, the butterworthing, the output, or whatever.
>
> Just my $0.02. Good luck!
>
> --Josh
>
> p.s:
>
> If anyone cares about the error I got, here you go:
>
> In [12]: a,b=wavfile.read('viacom2.wav')
> Reading fmt chunk
> Reading data chunk
> Warning:  %s chunk not understood
> ---------------------------------------------------------------------------
> error                                     Traceback (most recent call last)
>
> /home/josh/<ipython console> in <module>()
>
> /usr/lib/python2.6/site-packages/scipy/io/wavfile.pyc in read(file)
>     65         else:
>     66             print "Warning:  %s chunk not understood"
> ---> 67             size = struct.unpack('I',fid.read(4))[0]
>     68             bytes = fid.read(size)
>     69     fid.close()
>
> error: unpack requires a string argument of length 4
>
> The file could be borked for all I know, and maybe this was fixed a
> long time ago and my scipy package (probably stock fedora) could be a
> bit stale, but the %s bit makes me think that maybe that part wasn't
> completely finished? Anyways.
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