Festival Speech Synthesis System: - Speech Resource Pages

for i in wave/*.wav
do
fname=`basename $i .wav`
echo $i
lpc_analysis -reflection -shift 0.01 -order 18 -o lpc16k/$fname.lpc \
-r lpc16k/$fname.res -otype htk -rtype nist $i
done
It is said that the LPC order should be sample rate divided by one thousand plus 2. This may or may not be
appropriate and if you are particularly worried about the database size it is worth experimenting.
The program `lpc_analysis', found in `speech_tools/bin', can be used to generate the lpc coefficients
and residual. Note these should be reflection coefficients so they may be quantised (as they are in group files).
The coefficients and residual files produced by different LPC analysis programs may start at different offsets. For
example the Entropic's ESPS functions generate LPC coefficients that are offset by one frame shift (e.g. 0.01
seconds). Our own `lpc_analysis' routine has no offset. The Diphone_Init parameter list allows these
offsets to be specified. Using the above function to generate the LPC files the description parameters should include
(lpc_frame_offset 0)
(lpc_res_offset 0.0)
While when generating using ESPS routines the description should be
(lpc_frame_offset 1)
(lpc_res_offset 0.01)
The defaults actually follow the ESPS form, that is lpc_frame_offset is 1 and lpc_res_offset is equal to
the frame shift, if they are not explicitly mentioned.
Note the biggest problem we have in implementing the residual excited LPC resynthesizer was getting the right part
of the residual to line up with the right LPC coefficients describing the pitch mark. Making errors in this degrades the
synthesized waveform notably, but not seriously, making it difficult to determine if it is an offset problem or some
other bug.
Although we have started investigating if extracting pitch synchronous LPC parameters rather than fixed shift
parameters gives better performance, we haven't finished this work. `lpc_analysis' supports pitch synchronous
analysis but the raw "ungrouped" access method does not yet. At present the LPC parameters are extracted at a
particular pitch mark by interpolating over the closest LPC parameters. The "group" files hold these interpolated
parameters pitch synchronously.
The American English voice `kd' was created using the speech tools `lpc_analysis' program and its set up
should be looked at if you are going to copy it. The British English voice `rb' was constructed using ESPS
routines.
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21.3 Group files
Databases may be accessed directly but this is usually too inefficient for any purpose except debugging. It is expected
that group files will be built which contain a binary representation of the database. A group file is a compact efficient
representation of the diphone database. Group files are byte order independent, so may be shared between machines
of different byte orders and word sizes. Certain information in a group file may be changed at load time so a database
name, access strategy etc. may be changed from what was set originally in the group file.
A group file contains the basic parameters, the diphone index, the signal (original waveform or LPC residual), LPC
coefficients, and the pitch marks. It is all you need for a run-time synthesizer. Various compression mechanisms are