[Openal] Sound Attributes

[Skuzz Skuzz]

Hi,

To drive graphical output based on the audio data, you'll need to analyze 
the audio data. Obviously OpenAL doesn't give you access to the data (it's a 
one way street), so you'll have to either:

Keep a copy of your sample data as a source for frequency analysis, or..

Use streaming to play your sound, and perform the analysis on the packets of 
data before you queue them on the source.


There are plenty of code examples at http://www.musicdsp.org , in particular 
I *think* you need to look at the Archives > Analysis section for 'Fourier 
Transforms' to extract frequency information (like, how much bass, midrange, 
treble, high end e.t.c)

DSP coding looks damn scarey to me :)


Good luck!



>From: Tyhja <EugeneSeah at hotmail.com>
>To: openal at opensource.creative.com
>Subject: Re: [Openal] Sound Attributes
>Date: Sun, 30 Sep 2007 02:34:28 -0700 (PDT)
>
>
>
>Jason Daly wrote:
> >
> > Tyhja wrote:
> >> I have been searching extensively about openAL and trying to find
> >> functions
> >> or libraries that allow you to extract attributes of the sound
> >> stream/file
> >> that is being processed, eg volume,pitch, etc.
> >>
> >
> > Volume and pitch are relative values to OpenAL.  That is, all files and
> > buffers you give it are considered 1.0.  If you attach the buffer to a
> > source and set the gain or pitch of the source to a different value, it
> > alters the sound output appropriately when played.
> >
> > Can you explain in more detail what exactly you're trying to do?
> >
> > --
> >
> > --"J"
> >
> > "I'm a castaway stranded in a desolate land,
> >  I can see the footprints in the virtual sand."
> > 	--Neil Peart
> >
> > _______________________________________________
> > Openal mailing list
> > Openal at opensource.creative.com
> > http://opensource.creative.com/mailman/listinfo/openal
> >
> >
>
>Hi Daniel and Jason,
>
>Thanks for replying. What i am trying to do is to drive a graphical output
>based on the changing values of the sound input -- something like a sound
>visualisation, if you will. So, you see, i am trying to get the values in
>the wave not the file, to affect my visualisation. Searching through the
>library, it seems i find that there are functions to get values, but they
>are the file values like file frequency 44100 for example. Am i on the 
>right
>track here? I'm sorry if this seems trivial to you, i just started on 
>openAL
>and i greatly appreciate the help so far.
>--
>View this message in context: 
>http://www.nabble.com/Sound-Attributes-tf4472225.html#a12964129
>Sent from the OpenAL - User mailing list archive at Nabble.com.
>
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