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.
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¶