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 value.
-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
-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 use).
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 support.
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.
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
MIT Media Lab
MIT Media Lab,