The previous section gives the low level details ofin
the building of a cluster unit selection voice. This section
gives a higher level view with explict command that you
should run.
The steps involved in building a unit selection voices are basically
the same as that for building a limited domain voice (Chapter 5). Though in for general voices, in constrast
to ldom voice, it is much more important to get all parts correct,
from pitchmarks to labeling.
The following tasks are required:
Read and understand all the issues regarding the following
steps
Design the prompts
Record the prompts
Autolabel the prompts
Build utterance structures for recorded utterances
Extract pitchmark and build LPC coefficients
Building a clunit based synthesizer from the utterances
Testing and tuning
The following are the commands that you must type (assuming all the
other hardwork has been done beforehand. It is assume that the
environment variables FESTVOXDIR and
ESTDIR have been set to point to their respective
directories. For example as
export FESTVOXDIR=/home/awb/projects/festvox
export ESTDIR=/home/awb/projects/1.4.3/speech_tools
Next you must select a name for the voice, by convention we use
three part names consisting of a institution name, a language, and
a speaker. Make a directory of that name and change directory into it
mkdir cmu_us_awb
cd cmu_us_awb
There is a basic set up script that will construct the directory
structure and copy in the template files for voice building.
If a fourth argument is given, it can be name
one of the standard prompts list.
For example the simplest is
uniphone. This contains three sentences which
contain each of the US English phonemes once (if spoken appropriately).
This prompt set is hopelessly minimal for any high quality synthesis
but allows us to illustrate the process and allow you to build a voice
quickly.
$FESTVOXDIR/src/unitsel/setup_clunits cmu us awb uniphone
Alternatively you can copy in a prompt list into the etc directory.
The format of these should be in the standard "data" format
as in
( uniph_0001 "a whole joy was reaping." )
( uniph_0002 "but they've gone south." )
( uniph_0003 "you should fetch azure mike." )
Note the spaces after the initial left parenthesis are significant,
and double quotes and backslashes within the quote part must be
escaped (with backslash) as is common in Perl or Festival itself.
The next stage is to generate waveforms to act as prompts, or timing
cues even if the prompts are not actually played. The files are also
used in aligning the spoken data.
festival -b festvox/build_clunits.scm '(build_prompts "etc/uniphone.data")'
Use whatever prompt file you are intending to use. Note that you may
want to add lexical entries to
festvox/WHATEVER_lexicon.scm and other text
analysis things as desired. The purpose is that the prompt files
match the phonemes that the voice talent will actually say.
You may now record, assuming you have prepared the recording studio,
gotten written permission to record your speaker (and explained
to them what the resulting voice might be used for), checked recording
levels and sound levels and shield the electrical equipment as
much as possible.
./bin/prompt_them etc/uniphone.data
After recording the recorded files should be in
wav/.
It is wise to check that the are actually there and sound like you expected.
Getting the recording quality as high as possible is fundamental to
the success of building a voice.
Now we must label the spoken prompts. We do this my matching
the synthesized prompts with the spoken ones. As we know where the
phonemes begin and end in the synthesized prompts we can then map
that onto the spoken ones and find the phoneme segments. This
technique works fairly well, but it is far from perfect and it
is worthwhile to at least check the result, and most probably fix
the result by hand.
./bin/make_labs prompt-wav/*.wav
Especially in the case of the uniphone synthesizer, where there is
one and only one occurrence of each phone they all must be correct
so its important to check the labels by hand. Note for
large collections you may find the full Sphinx based labeling
technique better
Section 13.2).
After labeling we can build the utterance structure using the prompt
list and the now labeled phones and durations.
festival -b festvox/build_clunits.scm '(build_utts "etc/uniphone.data")'
The next stages are concerned with signal analysis, specifically pitch
marking and cepstral parameter extraction. There are a number of
methods for pitch mark extraction and a number of parameters within
these files that may need tuning. Good pitch periods are important.
See Section 4.7 . In its simplest
case the follow may work
./bin/make_pm_wave wav/*.wav
The next stage it find the Mel Frequency Cepstral Coefficents. This
is done pitch synchronously and hence depends on the pitch periods extracted
above. These are used for clustering and for join measurements.
./bin/make_mcep wav/*.wav
Now we can do the main part of the build, building the cluster unit
selection synthesizer. This consists of a number os
stages all based on the controlling Festival script. The
parameters of which are described above.
festival -b festvox/build_clunits.scm '(build_clunits "etc/uniphone.data")'
For large databases this can take some time to run as there is a
squared aspect to this based on the number of instances of
each unit type.
