[SciPy-Dev] scipy.io.wavfile

Warren Weckesser warren.weckesser@enthought....
Mon Jan 16 14:30:13 CST 2012


On Mon, Jan 16, 2012 at 2:18 PM, Jean-Louis Durrieu
<jean-louis@durrieu.ch>wrote:

> Hi everyone,
>
> I have been using the scipy.io.wavfile for some time now. I am quite
> thankful for the person(s) who contributed that, as it makes it easy for me
> to research, develop and have other people use my programs. And it's easier
> to install than audiolab (sorry david), but way less powerful (is that
> better? :) ).
>
> I just found a strange behaviour, and wanted to know what could be done: I
> have a few wav files for which I got, with scipy.io.wavfile.read, the right
> sampling rate, but a bad data chunk (actually strings, instead of int).
>
> As it were, these files (from the MIREX tempo tracking challenge
> http://www.music-ir.org/mirex/wiki/2011:Audio_Beat_Tracking) do have
> strange chunks, appended to the data chunk, which contain stuff like
> annotations or labels. While audacity or any other program does not bother
> with these, scipy.io.wavfile.read still reads them and, worse of all,
> replaces the correct data chunk with these labels (and we get a warning
> saying it does not understand the data type, and reads rubbish instead).
>
> Well, I was wondering if such a behaviour was desired, or if there should
> not just be something like:
> * If there is a data chunk, read it.
> * If there are many such data chunks, keep the first, send a warning.
> * If there is a data chunk, and other "funny ones", keep the data chunk,
> send warning about the others (like providing their chunk_ids?)
> * If there is no data chunk, send an error (with list of found chunks?).
>
> That would at least make it not break at the first difficulty, right? Of
> course, I might be wrong assuming the above cases are the only ones that
> could occur, but one has to start somewhere, eh?
>
>

You're not the first to encounter a problem like this.  Someone else
reported almost the same issue just a few days ago:

    http://projects.scipy.org/scipy/ticket/1585



> Additionally, I was wondering why numpy does not recognize 24 bits
> integers. It would seem quite some people work with 24 bit audio, so maybe
> some conversion should also be allowed there, although using numpy.fromfile
> may not work anymore (except if we add 24 bit integers to the allowed data
> types...). For this matter, I m more curious than pushy, so no need to
> stress about it :-)
>
>
For the record, this has also been suggested before:

    http://projects.scipy.org/scipy/ticket/1405


Cheers,

Warren
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