[Asterisk-Dev] Text to speech on Asterisk

[Chris Albertson]

The reason Festival sound poor with Asterisk is that be default
it is used in its "dumbest default mode".  It _can_ sound
quite well and even speeak in a given voice and use proper tone
inflection.  The troble is that the Asterisk app makes use
of a simple demo feature of Festival.

You'll have to read the Festival docs and perhaps join a 
Festival e-mail list but it can be made to sound quite 
natural.

As a first step rather then sending pure text, you can send
"marked up" text.  You can mark up text like HTML with tags
like "slow", or "ordinal number" or to change the voice to
"femail#3" or whathave you for.  Festival is a research grade
system an reresents the current state of the art in machine
speech but it's a "tool kit", not a product..



--- astdev at newww.com wrote:
> I'd like to kick around some ideas about using various text to speech
> engines with *.
> 
> First a question, I few weeks ago someone made a comment about using
> Cepstral with *. Is the Cepstral TTS for Linux a direct replacement
> for Festival? or is there a app_cepstral that exists somewhere? The
> quality of Cepstral is such that I wouldn't mind spending $30 just to
> try it out.  So I'm looking for info on how to use it with *
> 
> Second - I'd like to get a discussion going about TTS with Asterisk
> in
> general.
> 
> I've been using * since mid-summer and got festival working more or
> less right away. Not wanting to start a battle over the "Quality" of
> speech generated by Festival - using it as configured right out of
> the
> box - it's not good enough for my application. Of course assessing
> the
> "Quality" of TTS is a rather subjective - it depends on the nature of
> the text being spoken. For instance, I've used festival to read long
> blocks of text, such as email or fiction and it is rather
> comprehensible, but when used to read names and addresses, I often
> can't understand it.
> 
> There was a thread back in July with this post:
>
<http://lists.digium.com/pipermail/asterisk-users/2003-July/015962.html>
> that mentions that festival out of the box is using a "demo" voice
> and
> that one can create new voices and embed markup etc. that will
> improve
> festival. I think most of us don't have the time or expertise to get
> this done and would rather contribute/fund/test or buy a commercial
> package. Has anyone on this list worked on improving festival that is
> willing to share?
> 
> Festival appears to be the only open-source TTS option for use with
> *. There are other commercial TTS that range in price and quality
> several of which are based on festival. It seems to me that it would
> be a good approach to create a generic app_tts that could then use
> whatever backend engine the developer desires. This would be similar
> to the way Perl handles database engines thru the DBI/DBD
> modules. Anyone could write a TTS "driver" for a particular engine
> that could then be plugged in / specified by the app_tts. If the
> general opinion is that this is a good idea, I'd be happy to take the
> project on.
> 
> SO - What TTS engines are currently being used with Asterisk? So far
> I've only found evidence of Festival and Cepstral. Others mentioned
> in
> the list are AT&T Natural Voice, ScanSoft RealSpeak.
> 
> The other side of this is getting the commercial vendors to work with
> us. I've started talking to both Rhetorical and Elanspeech - with
> minor success. They need to be convinced that there is enough demand
> to make working with us viable and in general they want NDA's
> signed. By having an architecture that splits the diver from the
> interface - companies that insist on keeping the API's private could
> not release the source. I think that if enough interest is shown a
> company could be convinced to support the development of a TTS driver
> and wouldn't mind having their API exposed to the extent it was used
> in the driver (the writer of the driver wouldn't be publishing the
> API
> docs, the driver would just be an example of using the commercial
> API).
> 
> Depending on where this all leads, we would need to document /
> demonstrate real (ie. revenue generating) interest in commercial
> TTS. This is likely another thread in the future. 
> 
> Please don't take this as an Open vs. Commercial fight - I'd like to
> see the TTS choices for Asterisk, both commercial and open, greatly
> increased and I believe that this would be a very good thing for
> Asterisk, in much the same way as the choice of backend database is
> wide open for Perl. (oh yeah, it would also be nice to have a similar
> way to plug any database into *).
> 
> What do you think?
> 
>          Dave
> 
> 
> 
> _______________________________________________
> Asterisk-Dev mailing list
> Asterisk-Dev at lists.digium.com
> http://lists.digium.com/mailman/listinfo/asterisk-dev


=====
Chris Albertson
  Home:   310-376-1029  chrisalbertson90278 at yahoo.com
  Cell:   310-990-7550
  Office: 310-336-5189  Christopher.J.Albertson at aero.org
  KG6OMK

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