From: Hans Fugal <hans@...>
Date: 2005-11-15T23:17:17+09:00
Subject: Re: RFC: Audio

On Tue, 15 Nov 2005 at 04:58 -0500, Jay Levitt wrote:
> > My plans for this are simple: wrap libsndfile, libsamplerate, and
> > possibly portaudio. Combined with ladspar, midilib, and other ruby audio
> > libs that exist, this should get us well on the way.
> 
> Looks really good, and the NArray interface is simple.  What do you 
> think about wrapping libmad?  

Possibly, after all the others.

> I need to write a simple utility that monitors a streaming audio server 
> for silence, and pages me when it detects an outage.  Seems like all I 
> need is libmad and some code to detect a bunch of zeros... perfect for a 
> simple ruby script, if the bindings were there.  Ya?
> 
> Ah, but how does NArray deal with the constant resizing resulting from 
> an ongoing stream?  Is there a copy each time?

I'm not sure how libmad's interface is, and I've never really done
streaming before, but to my understanding you would generally want to
decode a fixed amount each 'period', since that's how you're going to
feed it to the soundcard anyway. You could always do a 'big enough'
array and fill it partially if needed. 

You could probably do this now if you use mpg123 and/or sox and output
to a raw format on stdout and read that into an NArray (or you can be a
tester for the Audio class - it works now, but the API is still subject
to change).