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Linux 2.6 - man page for hetro (linux section 1)

HETRO(1)			  The Canonical Csound Reference			 HETRO(1)

       hetro - Decomposes an input soundfile into component sinusoids. .

       Hetrodyne filter analysis for the Csound adsyn generator.

	   csound -U hetro [flags] infilename outfilename

	   hetro [flags] infilename outfilename

       hetro takes an input soundfile, decomposes it into component sinusoids, and outputs a
       description of the components in the form of breakpoint amplitude and frequency tracks.
       Analysis is conditioned by the control flags below. A space is optional between flag and

       -s srate -- 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.
       Note that for adsyn synthesis the srate of the source file and the generating orchestra
       need not be the same.

       -c channel -- channel number sought. The default is 1.

       -b begin -- beginning time (in seconds) of the audio segment to be analyzed. The default
       is 0.0

       -d duration -- duration (in seconds) of the audio segment to be analyzed. The default of
       0.0 means to the end of the file. Maximum length is 32.766 seconds.

       -f begfreq -- estimated starting frequency of the fundamental, necessary to initialize the
       filter analysis. The default is 100 (cps).

       -h partials -- number of harmonic partials sought in the audio file. Default is 10,
       maximum is a function of memory available.

       -M maxamp -- maximum amplitude summed across all concurrent tracks. The default is 32767.

       -m minamp -- amplitude threshold below which a single pair of amplitude/frequency tracks
       is considered dormant and will not contribute to output summation. Typical values: 128 (48
       db down from full scale), 64 (54 db down), 32 (60 db down), 0 (no thresholding). The
       default threshold is 64 (54 db down).

       -n brkpts -- initial number of analysis breakpoints in each amplitude and frequency track,
       prior to thresholding (-m) and linear breakpoint consolidation. The initial points are
       spread evenly over the duration. The default is 256.

       -l cutfreq -- substitute a 3rd order Butterworth low-pass filter with cutoff frequency
       cutfreq (in Hz), in place of the default averaging comb filter. The default is 0 (don't

       As of Csound 4.08, hetro can write SDIF ouput files if the output file name ends with
       ".sdif" or ".SDIF". See the sdif2ad utility for more information about the Csound's SDIF

	   hetro -s44100 -b.5 -d2.5 -h16 -M24000 audiofile.test adsynfile7

       This will analyze 2.5 seconds of channel 1 of a file "audiofile.test", recorded at 44.1
       kHz, beginning .5 seconds from the start, and place the result in a file "adsynfile7". We
       request just the first 16 harmonics of the sound, with 256 initial breakpoint values per
       amplitude or frequency track, and a peak summation amplitude of 24000. The fundamental is
       estimated to begin at 100 Hz. Amplitude thresholding is at 54 db down.

       The Butterworth LPF is not enabled.

   File Format
       The output file contains time-sequenced amplitude and frequency values for each partial of
       an additive complex audio source. The information is in the form of breakpoints (time,
       value, time, value, ....) using 16-bit integers in the range 0 - 32767. Time is given in
       milliseconds, and frequency in Hertz (cps). The breakpoint data is exclusively
       non-negative, and the values -1 and -2 uniquely signify the start of new amplitude and
       frequency tracks. A track is terminated by the value 32767. Before being written out, each
       track is data-reduced by amplitude thresholding and linear breakpoint consolidation.

       A component partial is defined by two breakpoint sets: an amplitude set, and a frequency
       set. Within a composite file these sets may appear in any order (amplitude, frequency,
       amplitude ....; or amplitude, amplitude..., then frequency, frequency,...). During adsyn
       resynthesis the sets are automatically paired (amplitude, frequency) from the order in
       which they were found. There should be an equal number of each.

       A legal adsyn control file could have following format:

	   Author: Tom Sullivan
	   Author: John ffitch
	   Author: Richard Dobson

       October 2002. Thanks to Rasmus Ekman, added a note about the SDIF format.

       Barry Vercoe
       MIT Media Lab


       Dan Ellis
       MIT Media Lab,


5.07					    06/23/2009					 HETRO(1)

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