Comparing audio files

[kieran]

Hello,
I am trying to compare two similar audio files (WAV). From what i have
read i need to sample both audio files at certain frequencies and run
these through a FFT and then compare the results. Can anyone advise me
if this is the correct approach and also describe the steps i need to
take to get to the stage where I can compare the files.
TIA,
Kieran

 

[Jürgen Exner]

I am trying to compare two similar audio files (WAV). From what i have
read i need to sample both audio files at certain frequencies and run
these through a FFT and then compare the results. Can anyone advise me
if this is the correct approach and also describe the steps i need to
take to get to the stage where I can compare the files.

You could try the ESP:SI module.

jue

 

[kieran]

You could try the ESP:SI module.

jue

Hi Jue,
thanks for your reply, i have searched for the module you mentiones in
CPAN and Google but could not find it.
Can you please send me a link.
Best Regards,
Kieran

 

[greymaus]

Hi Jue,
thanks for your reply, i have searched for the module you mentiones in
CPAN and Google but could not find it.
Can you please send me a link.
Best Regards,
Kieran

The reply may, just may, be his attempt at humour. You can try the NSA!.

 

[RedGrittyBrick]

The reply may, just may, be his attempt at humour. You can try the NSA!.

Surely there's an Acme::ESP and Acme:SI in CPAN?

--
RGB

* ***
*** *
*

 

[Ted Zlatanov]

R> Surely there's an Acme::ESP and Acme:SI in CPAN?

I put PSI::ESP in this article but IBM screwed up the link (made it
lowercase):
http://www.ibm.com/developerworks/linux/library/l-perl1/

The real link is:
http://www.ibm.com/developerworks/linux/library/l-perl1/ESP.pm

Ted

 

[RedGrittyBrick]

R> Surely there's an Acme::ESP and Acme:SI in CPAN?

I put PSI::ESP in this article but IBM screwed up the link (made it
lowercase):
http://www.ibm.com/developerworks/linux/library/l-perl1/

The real link is:
http://www.ibm.com/developerworks/linux/library/l-perl1/ESP.pm

Nice article!

I admit I was thinking of things like this:
http://search.cpan.org/~tyemq/Acme-ESP-1.002007/ESP.pm

 

[kieran]

While this can certainly be done in Perl, a nice environment for
prototyping this kind of applications is GNU Octave or Matlab (given
you are rich or a student). Reading some files from wav,down/
upsampling them, applying filters and perform an fft is just a few
lines of code in both of these tools.

Once you have a working solution, you can still collect all modules
you need to do it in Perl from CPAN or just continue to use Octave via
Inline::Octave.

Now for what to do exactly, this heavily depends on what your input
and your goals are. To get help with this, maybe asking in a group
about audio processing or algorithms would be better.

Good luck

Christian

Hi Christian,
Thanks for your reply, the approach you describe will certainly help,
I have requested a trial version of Octave so I will begin using that
for protoyyping once I get access.

A couple of things you might be able to help me with, I have been
looking for some modules to use for downsampling, filtering etc... The
module I found for resampling audio called Audio::Mad::Resample would
not install on my machine, i got some errors that i could not resolve.
Are there any modules you can recomend for down/up sampling?
Also for creating a low-pass filter i have been looking at PDL::Audio,
there are many types of filter available in this module, I am not sure
which is best for low-pass filters.
Thanks,
Kieran

 

[kieran]

Hi Christian,
Thanks for your reply, the approach you describe will certainly help,
I have requested a trial version of Octave so I will begin using that
for protoyyping once I get access.

A couple of things you might be able to help me with, I have been
looking for some modules to use for downsampling, filtering etc... The
module I found for resampling audio called Audio::Mad::Resample would
not install on my machine, i got some errors that i could not resolve.
Are there any modules you can recomend for down/up sampling?
Also for creating a low-pass filter i have been looking at PDL::Audio,
there are many types of filter available in this module, I am not sure
which is best for low-pass filters.
Thanks,
Kieran

Hello,
I have done some of the work in prototyping the wav file comparison in
MATLAB and I have begun translating this into perl. I am experiencing
some problems when I read the data from the wave file in perl, the
values I am getting seem very large and seem to be 3,000(aprox.) times
larger than the values i get when i imported the wav file data into
Matlab. When I graph both sets of values the resulting graphs look the
same as the wave form.
In matlab i am using the wavread function to read the samples from my
wav file. I get 49617 samples of very low numbers, lots of zero values
and plenty of very low and negative values. I have followed a few
tutorials in Matlab and these reading look correct.
However when i attempt to do the same in perl i get the smae ammount
of samples but the numbers are very large and with few if any zero
readings. I have been uing the Audio::Analyzer Audio::Wav::Read
modules.
Can you explain why I am getting such a large difference between
Matlab nad perl? I would expect the results to match.
If you require any more information please let me know.
Regards,
Kieran