NAME
lpanal - Performs both linear predictive and pitch-tracking analysis on
a soundfile. .
DESCRIPTION
Linear predictive analysis for the Csound Linear Predictive Coding
(LPC) Resynthesis opcodes.
SYNTAX
csound -U lpanal [flags] infilename outfilename
lpanal [flags] infilename outfilename
INITIALIZATION
lpanal performs both lpc and pitch-tracking analysis on a soundfile to
produce a time-ordered sequence of frames of control information
suitable for Csound resynthesis. Analysis is conditioned by the control
flags below. A space is optional between the flag and its value.
-a -- [alternate storage] asks lpanal to write a file with filter poles
values rather than the usual filter coefficient files. When lpread /
lpreson are used with pole files, automatic stabilization is performed
and the filter should not get wild. (This is the default in the Windows
GUI) - Changed by Marc Resibois.
-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.
-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.
-p npoles -- number of poles for analysis. The default is 34, the
maximum 50.
-h hopsize -- hop size (in samples) between frames of analysis. This
determines the number of frames per second (srate / hopsize) in the
output control file. The analysis framesize is hopsize * 2 samples. The
default is 200, the maximum 500.
-C string -- text for the comments field of the lpfile header. The
default is the null string.
-P mincps -- lowest frequency (in Hz) of pitch tracking. -P0 means no
pitch tracking.
-Q maxcps -- highest frequency (in Hz) of pitch tracking. The narrower
the pitch range, the more accurate the pitch estimate. The defaults are
-P70, -Q200.
-v verbosity -- level of terminal information during analysis.
· 0 = none
· 1 = verbose
· 2 = debug
The default is 0.
EXAMPLES
lpanal -a -p26 -d2.5 -P100 -Q400 audiofile.test lpfil22
will analyze the first 2.5 seconds of file "audiofile.test", producing
srate/200 frames per second, each containing 26-pole filter
coefficients and a pitch estimate between 100 and 400 Hertz. Stabilized
(-a) output will be placed in "lpfil22" in the current directory.
File Format
Output is a file comprised of an identifiable header plus a set of
frames of floating point analysis data. Each frame contains four values
of pitch and gain information, followed by npoles filter coefficients.
The file is readable by Csound´s lpread.
lpanal is an extensive modification of Paul Lanksy´s lpc analysis
programs.
AUTHORS
Barry Vercoe
MIT Media Lab
Author.
Dan Ellis
MIT Media Lab,
Cambridge
Massachussetts
Author.
COPYRIGHT