====== Text-To-Speech Guide ======

© 2014 I6NET Solutions and Technologies, all rights reserved

===== Purpose =====

The VXI%%*%% VoiceXML browser integrates an HTTP client interface to connect to an HTTP text-to-speech (TTS) server. This allows for dynamically generated audio content with a text-to-speech engine. Most VoiceXML browsers have an MRCP (Media Resource Control Protocol) interface to access text-to-speech features. The advantage however, of using the HTTP connector is that the “speech” generated is cached by the VoiceXML Browser, and re-used the next time.  The text is posted via an HTTP request then the server responds with a standard wav file.  Users can use the TTS to generate menus prompts, for example, without need to purchase a lot of TTS licenses. The integrated TTS packages use PHP, so you need to have an Apache/PHP already installed on your server (MySQL is optional, it allows to produce “CDR” like reporting information to evaluate the TTS using).

===== Scope =====

    * [[legacy:text-to-speech_guide:flite_tts:start|Flite TTS]]
    * Mbrola TTS
    * [[legacy:text-to-speech_guide:loquendo_tts:start|Loquendo TTS]]
    * [[legacy:text-to-speech_guide:acapela_tts:start|Acapela TTS]]
    * [[legacy:text-to-speech_guide:cepstral_tts:start|Cepstral TTS]]
    * [[legacy:text-to-speech_guide:verbio_tts:start|Verbio TTS]]
    * [[legacy:text-to-speech_guide:voxygen_tts:start|Voxygen TTS]]
    * Nuance TTS
    * Neospeech TTS
    * Lumenvox TTS
    * Ivona TTS

===== Usage =====

You can you two type of connections
  * HTTP access
  * MRCP access

==== HTTP ====

To use TTS by HTTP, you need to configure vxi.
In /etc/openvxi/client.cfg set ''**POST**'' value in ''**client.prompt.resource.0.method**'' key
<code>
client.prompt.resource.0.method             VXIString   POST
</code>

==== HTTP ====

To use TTS by MCRP, you need to configure vxi, and configure asterisk to use TTS with MRCP.

To configure VXI, set in ''**/etc/openvxi/client.cfg**'' the ''**ASTERISK**'' in ''**client.prompt.resource.0.method**'' key
<code>
client.prompt.resource.0.method             VXIString   ASTERISK
</code>

To configure asterisk, update the file ''**/etc/asterisk/mrcp.conf**'' 
<code>
[speech-loquendo-mrcp1]
version = 1
server-ip = 192.168.100.164
server-port = 554
resource-location = media
speechsynth = speechsynthesizer
speechrecog = speechrecognizer
rtp-ip = 192.168.100.134
;rtp-ip = 192.168.1.2
;rtp-ext-ip = auto
rtp-port-min = 5100
rtp-port-max = 5999
playout-delay = 50
;min-playout-delay = 20
max-playout-delay = 200
ptime = 20
codecs = PCMU PCMA L16/96/8000
rtcp = 1
rtcp-bye = 2
rtcp-tx-interval = 5000
rtcp-rx-resolution = 1000
</code>