Thread: Re: [Audacity-nyquist] Working with samples
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From: <edg...@we...> - 2007-08-13 01:16:47
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> I'm trying to write my first plugin, but I'm not making much progress. What I > want to do is "clean" the selected segment by replacing each sample at > position [i] with the average of samples from [i-n] to [i+n]. That means that > I need to access the samples directly. You can use 'snd-avg' (sound-average) for this. > First, I need to determine the number of channels, as well as the number of > samples in the channels. I tried using > > (length s) > > but that didn't seem to work. What's the correct way to get the size of an > array? How to compute the length of a track [or selection] please look at the 'Audacity Nyquist FAQ' I had posted three or four month ago to this list [see the SourceForge archives]. You can differ between mono and stereo tracks by using 'arrayp s' If 's' is an array [arrayp returns T] the track is in stereo. In this case the left channel can be refered by 'aref s 0' and the right channel by 'aref s 1'. If the track is mono [arrayp returns NIL] you can process the 's' variable [containing the the Audacity sound] as-is. > Second, how do I get to the samples? If I grab a given channel, will I get an > array of samples, or do I have to dig deeper? If the sound is mono you could just write: (snd-avg s [Parameters]) and the return value will be automatically given back to Audacity. For the exact parameters please look into the Nyquist manual [I don't know myself just 'out of my head']. If you need more information about XLISP [the language Nyquist is based on], see: http://www.audacity-forum.de/download/edgar/nyquist/nyquist-doc/xlisp/xlisp-index.htm The most actual Nyquist manual always can be found on Roger's page at the CMU: http://www.cs.cmu.edu/~music/music.software.html greetings, - edgar -- The author of this email does not necessarily endorse the following advertisements, which are the sole responsibility of the advertiser: _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066 |