ref: 7de74a9d01cbb87b74def34099ce2f30a0fb6e6e
dir: /modules/data/lpc.lua/
sptbl["lpc"] = {
files = {
module = "lpc.c",
header = "lpc.h",
example = "ex_lpc.c",
},
func = {
create = "sp_lpc_create",
destroy = "sp_lpc_destroy",
init = "sp_lpc_init",
compute = "sp_lpc_compute",
other = {
sp_lpc_synth = {
description = [[Toggle synth mode.
Instead of reading an input, manipulate the parameters in
a scaled ftable.]],
args = {
{
name = "ft",
type = "sp_ftbl *",
description = "ftable of size 7",
default = "N/A"
}
}
}
}
},
params = {
mandatory = {
{
name = "framesize",
type = "int",
description = "Sets the frame size for the encoder.",
default = 512
},
},
optional = {
}
},
modtype = "module",
description = [[A linear predictive coding filter.
This module is a wrapper for the open source library openlpc, which implements
the LPC10 audio codec optimized for speech signals. This module takes in an
input signal, downsamples it, and produces a decoded LPC10 audio signal, which
has a similar sound to that of a speak and spell. In this context, the LPC
signal is meant to be more of a audio effect rather than a utility for
communication.
Because the LPC10 encoder
relies on frames for encoding, the output signal has a few milliseconds of
delay. The delay can be calculated in seconds as (framesize * 4) / samplerate.
In addition to using the LPC as a decoder/encoder, this module can also be
set to synth mode. Instead of reading from an input signal, the LPC can
instead read from parameters set directly in a scaled ftable.
]],
ninputs = 1,
noutputs = 1,
inputs = {
{
name = "input",
description = "Input signal to be processed with LPC."
},
},
outputs = {
{
name = "output",
description = "LPC encoded signal."
},
}
}