Robust Affordable Speech Recognition
Plug-in Installation FAQ:
Asterisk for Linux
The following FAQ has been designed for plug-in installation for Asterisk for Linux.
- Is the VASRE plug-in the only method to work with Asterisk?
- What operating systems does the plug-in support?
- What versions of Asterisk does the plug-in support?
- Is there any prerequisite software that should be installed before the plug-in installation?
- I modified modules.conf to add the VASRE plug-in to Asterisk module list. How can I check if it is actually added?
- Does the VASRE sample dialplan support multiple languages?
- I modified extensions.conf, and made a call to Asterisk to test the VASRE sample dialplan, but, it doesn’t respond.
- I placed a call to the demo dialplan. It never listens to me, but keeps prompting something.
- Is there any way to choose a proper value of VdAmpThres?
1. Is the VASRE plug-in the only method to work with Asterisk?
No. The other method is to use the MRCP server and UniMRCP plug-in for Asterisk. Vestec recommends the latter method due to its higher flexibility. See the Installation Guide and MRCP Integration Guide for the details.
2. What operating systems does the plug-in support?
As of January 2011, the VASRE plug-in for Asterisk supports GNU/Linux only.
3. What versions of Asterisk does the plug-in support?
As of January 2011, Asterisk 1.4, 1.6.2, and 1.8 are supported.
4. Is there any prerequisite software that should be installed before the plug-in installation?
You must install Asterisk, before installing the plug-in. See the Asterisk Integration Guide for more details.
5. I modified modules.conf to add the VASRE plug-in to Asterisk module list. How can I check if it is actually added?
Run the module show command from the Asterisk Command Line Interface (CLI) to see whether res_speech.so and res_speech_vasre.so are listed. If they are not in the list, run module reload and retry.
6. Does the VASRE sample dialplan support multiple languages?
Yes, the Asterisk plug-in package contains multiple sample dialplans that work with all the languages supported by VASRE. As of November 1st, 2010, US English (en-US) and German (de-DE) are supported.
7. I modified extensions.conf, and made a call to Asterisk to test the VASRE sample dialplan, but, it doesn’t respond.
Check whether extensions.conf is correctly modified as described in the Asterisk Integration Guide. Run dialplan reload from the Asterisk CLI to apply the changes.
8. I placed a call to the demo dialplan. It never listens to me, but keeps prompting something.
This usually happens when background noise or the prompt message are fed to the recognition server as speech inputs. Open /opt/Vestec/vasre/Samples/Dialplan/langid_vasre-demo.conf, where langid represents the ID of the language the dialplan is written for. Search for the line setting the value of VdAmpThres. Increase the value of this parameter by 1000 and retry. Repeat this procedure until the dialplan waits for your speech.
9. Is there any way to choose a proper value of VdAmpThres?
Open the RM configuration file /etc/Vestec/vasre/vasre-rm-config.xml, and search for the XML element named max_amplitude_calculation. Set the value of this parameter to 1, and save the change. Restart the RM and server, and reload the dialplan. The Asterisk CLI will output the maximum amplitude of speech input just detected. If the noise or echo was falsely detected, make the value of VdAmpThres slightly higher than its maximum amplitude.
No. The other method is to use the MRCP server and UniMRCP plug-in for Asterisk. Vestec recommends the latter method due to its higher flexibility. See the Installation Guide and MRCP Integration Guide for the details.
2. What operating systems does the plug-in support?
As of January 2011, the VASRE plug-in for Asterisk supports GNU/Linux only.
3. What versions of Asterisk does the plug-in support?
As of January 2011, Asterisk 1.4, 1.6.2, and 1.8 are supported.
4. Is there any prerequisite software that should be installed before the plug-in installation?
You must install Asterisk, before installing the plug-in. See the Asterisk Integration Guide for more details.
5. I modified modules.conf to add the VASRE plug-in to Asterisk module list. How can I check if it is actually added?
Run the module show command from the Asterisk Command Line Interface (CLI) to see whether res_speech.so and res_speech_vasre.so are listed. If they are not in the list, run module reload and retry.
6. Does the VASRE sample dialplan support multiple languages?
Yes, the Asterisk plug-in package contains multiple sample dialplans that work with all the languages supported by VASRE. As of November 1st, 2010, US English (en-US) and German (de-DE) are supported.
7. I modified extensions.conf, and made a call to Asterisk to test the VASRE sample dialplan, but, it doesn’t respond.
Check whether extensions.conf is correctly modified as described in the Asterisk Integration Guide. Run dialplan reload from the Asterisk CLI to apply the changes.
8. I placed a call to the demo dialplan. It never listens to me, but keeps prompting something.
This usually happens when background noise or the prompt message are fed to the recognition server as speech inputs. Open /opt/Vestec/vasre/Samples/Dialplan/langid_vasre-demo.conf, where langid represents the ID of the language the dialplan is written for. Search for the line setting the value of VdAmpThres. Increase the value of this parameter by 1000 and retry. Repeat this procedure until the dialplan waits for your speech.
9. Is there any way to choose a proper value of VdAmpThres?
Open the RM configuration file /etc/Vestec/vasre/vasre-rm-config.xml, and search for the XML element named max_amplitude_calculation. Set the value of this parameter to 1, and save the change. Restart the RM and server, and reload the dialplan. The Asterisk CLI will output the maximum amplitude of speech input just detected. If the noise or echo was falsely detected, make the value of VdAmpThres slightly higher than its maximum amplitude.