[Speex-dev] Increasing the speed of speex playback

Bill Cox waywardgeek at gmail.com
Tue Oct 19 07:31:00 PDT 2010

Hi.  I'm Bill Cox, and I volunteer a bit for the Vinux project, which
is Linux for people with vision impairments.  Most blind users use a
closed-source speech synthesis tool called voxin, as it's very easy to
understand at high speed.  I would like to make TTS synthesizers based
on large recorded vocabularies of actual speech, but to make it useful
for the blind, I need to be able to speed up the speech while
maintaining excellent quality.

To date, I've been playing with low bit rate LPC coding, and it works,
which is very cool.  However, the quality of the voices I speed up are
too low.  The blind will hate me if try to switch them over to these
low quality voices.  I've tried both basic LPC-10, and MELPe.  Next, I
want to try modifying Speex to see if it can generate higher quality
voice at high speed.

Do you think this will this be a difficult or easy project?  Do you
think speex can be modified to generate very high quality voice at
high speed?  By high speed, I mean voice starting at about 2.5X speed
up, all the way up to aroun 8X speed up.  I haven't looked at any of
the code, yet, so any tips would be greatly appreciated.


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