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<H2>
CVANAL</H2>
<B>CVANAL</B> - Impulse Response Fourier Analysis for CONVOLVE operator
<PRE> csound -U cvanal [flags] infilename outfilename</PRE>
<B>cvanal</B> converts a soundfile into a single Fourier transform frame.
The output file can be used by the <B><A HREF="../Modifier/convolve.html">convolve</A></B>
operator to perform Fast Convolution between an input signal and the original
impulse response. Analysis is conditioned by the flags below. A space is
optional between the flag and its argument.
<P><I>-s<rate></I> sampling rate of the audio input file. This will
over-ride the srate of the soundfile header, which otherwise applies. If
neither is present, the default is 10000.
<P><I>-c<channel></I> channel number sought. If omitted, the default
is to process all channels. If a value is given, only the selected channel
will be processed.
<P><I>-b<begin></I> beginning time (in seconds) of the audio segment
to be analysed. The default is 0.0
<P><I>-d<duration></I> duration (in seconds) of the audio segment to
be analysed. The default of 0.0 means to the end of the file.
<H4>
<B><U>EXAMPLE:</U></B></H4>
<PRE> cvanal asound cvfile</PRE>
will analyse the soundfile "asound" to produce the file "cvfile" for the
use with CONVOLVE.
<P>HINT: To use data that is not already contained in a soundfile, a soundfile
converter that accepts text files may be used to create a standard audio
file. E.g, the .DAT format for SOX. This is useful for implementing FIR
filters.
<H4>
<B><U>FILES</U></B></H4>
The output file has a special <B><A HREF="../Modifier/convolve.html">convolve</A></B>
header, containing details of the source audio file. The analysis data
is stored as 'float', in rectangular (real/imaginary) form.
<P>***NOTE***: The analysis file is NOT system independent! Ensure that
the original impulse recording/data is retained. If/when required, the
analysis file can be recreated.
<P><B><U>AUTHOR:</U></B>
<P>Greg Sullivan
<BR>(Based on algorithm given in 'Elements Of Computer Music', by F. Richard
Moore.
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