| Hi,
I've modified the manual entries for lpread, lpreson, and lpfreson,
according to the historical vercoe manual, plus some additions.
The entries now read, please let me know if they are inaccurate:
---------------------------------------------
lpread
lpread — Reads a control file of time-ordered information frames.
Description
Reads a control file of time-ordered information frames.
Syntax
krmsr, krmso, kerr, kcps lpread ktimpnt, ifilcod [, inpoles] [,
ifrmrate]
Initialization
ifilcod -- integer or character-string denoting a control-file
(reflection coefficients and four parameter values) derived from n-pole
linear predictive spectral analysis of a source audio signal. An integer
denotes the suffix of a file lp.m; a character-string (in double quotes)
gives a filename, optionally a full pathname. If not fullpath, the file
is sought first in the current directory, then in that of the
environment variable SADIR (if defined). Memory usage depends on the
size of the file, which is held entirely in memory during computation
but shared by multiple calls (see also adsyn, pvoc).
inpoles (optional, default=0) -- number of poles in the lpc analysis. It
is required only when the control file does not have a header; it is
ignored when a header is detected.
ifrmrate (optional, default=0) -- frame rate per second in the lpc
analysis. It is required only when the control file does not have a
header; it is ignored when a header is detected.
Performance
lpread accesses a control file of time-ordered information frames, each
containing n-pole filter coefficients derived from linear predictive
analysis of a source signal at fixed time intervals (e.g. 1/100 of a
second), plus four parameter values:
krmsr -- root-mean-square (rms) of the residual of analysis
krmso -- rms of the original signal
kerr -- the normalized error signal
kcps -- pitch in Hz
ktimpnt -- The passage of time, in seconds, through the analysis file.
ktimpnt must always be positive, but can move forwards or backwards in
time, be stationary or discontinuous, as a pointer into the analysis
file.
lpread gets its values from the control file according to the input
value ktimpnt (in seconds). If ktimpnt proceeds at the analysis rate,
time-normal synthesis will result; proceeding at a faster, slower, or
variable rate will result in time-warped synthesis. At each k-period,
lpread interpolates between adjacent frames to more accurately determine
the parameter values (presented as output) and the filter coefficient
settings (passed internally to a subsequent lpreson).
The error signal kerr (between 0 and 1) derived during predictive
analysis reflects the deterministic/random nature of the analyzed
source. This will emerge low for pitched (periodic) material and higher
for noisy material. The transition from voiced to unvoiced speech, for
example, produces an error signal value of about .3. During synthesis,
the error signal value can be used to determine the nature of the
lpreson driving function: for example, by arbitrating between pitched
and non-pitched input, or even by determining a mix of the two. In
normal speech resynthesis, the pitched input to lpreson is a wideband
periodic signal or pulse train derived from a unit such as buzz, and the
nonpitched source is usually derived from rand. However, any audio
signal can be used as the driving function, the only assumption of the
analysis being that it has a flat response.
lpfreson is a formant shifted lpreson, in which kfrqratio is the (cps)
ratio of shifted to original formant positions. This permits synthesis
in which the source object changes its apparent acoustic size. lpfreson
with kfrqratio = 1 is equivalent to lpreson.
Generally, lpreson provides a means whereby the time-varying content and
spectral shaping of a composite audio signal can be controlled by the
dynamic spectral content of another. There can be any number of
lpread/lpreson (or lpfreson) pairs in an instrument or in an orchestra;
they can read from the same or different control files independently.
See Also
lpfreson, lpreson
--------------------------
lpreson
lpreson — Resynthesises a signal from the data passed internally by a
previous lpread.
Description
Resynthesises a signal from the data passed internally by a previous
lpread.
Syntax
ares lpreson asig
Performance
asig -- an audio driving function for resynthesis.
lpreson receives values internally produced by a leading lpread.lpread
gets its values from the control file according to the input value
ktimpnt (in seconds). If ktimpnt proceeds at the analysis rate,
time-normal synthesis will result; proceeding at a faster, slower, or
variable rate will result in time-warped synthesis. At each k-period,
lpread interpolates between adjacent frames to more accurately determine
the parameter values (presented as output) and the filter coefficient
settings (passed internally to a subsequent lpreson).
The error signal kerr (between 0 and 1) derived during predictive
analysis reflects the deterministic/random nature of the analyzed
source. This will emerge low for pitched (periodic) material and higher
for noisy material. The transition from voiced to unvoiced speech, for
example, produces an error signal value of about .3. During synthesis,
the error signal value can be used to determine the nature of the
lpreson driving function: for example, by arbitrating between pitched
and non-pitched input, or even by determining a mix of the two. In
normal speech resynthesis, the pitched input to lpreson is a wideband
periodic signal or pulse train derived from a unit such as buzz, and the
nonpitched source is usually derived from rand. However, any audio
signal can be used as the driving function, the only assumption of the
analysis being that it has a flat response.
lpfreson is a formant shifted lpreson, in which kfrqratio is the (cps)
ratio of shifted to original formant positions. This permits synthesis
in which the source object changes its apparent acoustic size. lpfreson
with kfrqratio = 1 is equivalent to lpreson.
Generally, lpreson provides a means whereby the time-varying content and
spectral shaping of a composite audio signal can be controlled by the
dynamic spectral content of another. There can be any number of
lpread/lpreson (or lpfreson) pairs in an instrument or in an orchestra;
they can read from the same or different control files independently.
See Also
lpfreson, lpread
--------------------------
lpfreson
lpfreson — Resynthesises a signal from the data passed internally by a
previous lpread, applying formant shifting.
Description
Resynthesises a signal from the data passed internally by a previous
lpread, applying formant shifting.
Syntax
ares lpfreson asig, kfrqratio
Performance
asig -- an audio driving function for resynthesis.
kfrqratio -- frequency ratio. Must be greater than 0.
lpfreson receives values internally produced by a leading lpread.lpread
gets its values from the control file according to the input value
ktimpnt (in seconds). If ktimpnt proceeds at the analysis rate,
time-normal synthesis will result; proceeding at a faster, slower, or
variable rate will result in time-warped synthesis. At each k-period,
lpread interpolates between adjacent frames to more accurately determine
the parameter values (presented as output) and the filter coefficient
settings (passed internally to a subsequent lpreson).
The error signal kerr (between 0 and 1) derived during predictive
analysis reflects the deterministic/random nature of the analyzed
source. This will emerge low for pitched (periodic) material and higher
for noisy material. The transition from voiced to unvoiced speech, for
example, produces an error signal value of about .3. During synthesis,
the error signal value can be used to determine the nature of the
lpreson driving function: for example, by arbitrating between pitched
and non-pitched input, or even by determining a mix of the two. In
normal speech resynthesis, the pitched input to lpreson is a wideband
periodic signal or pulse train derived from a unit such as buzz, and the
nonpitched source is usually derived from rand. However, any audio
signal can be used as the driving function, the only assumption of the
analysis being that it has a flat response.
lpfreson is a formant shifted lpreson, in which kfrqratio is the (cps)
ratio of shifted to original formant positions. This permits synthesis
in which the source object changes its apparent acoustic size. lpfreson
with kfrqratio = 1 is equivalent to lpreson.
Generally, lpreson provides a means whereby the time-varying content and
spectral shaping of a composite audio signal can be controlled by the
dynamic spectral content of another. There can be any number of
lpread/lpreson (or lpfreson) pairs in an instrument or in an orchestra;
they can read from the same or different control files independently.
See Also
lpread, lpreson
Cheers,
Andres
On Fri, 2005-12-02 at 14:19 +0000, jpff@codemist.co.uk wrote:
> The words for the entry for lpreson seem to refer to lpread. Either
> that or the explanation is confused.
> ==John ffitch
>
>
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