[Freeswitch-users] mod_rtmp audio codecs issues for speech recognition?

[Peter Olsson]

I noticed this as well when I was playing around with UniMRCP and Nuance some time ago. mod_unimrcp  seems to be missing some code to resample the audio frames to the bitrate used by the nuance connection. If I remember correctly it was ok to use (for instance) PCMA on the call leg and PCMU on the nuance leg (they both use 8khz), but as soon as I tried to use a codec with another rate things seemed to stop working.

I never had the time to chase this down any further, and I was only trying it for an internal test case, so it wasn't so important for me.

I believe the best thing you can do is to report this to Jira, and hopefully someone will be able to look into this.

/Peter

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Skickat: den 15 augusti 2012 13:35
Till: freeswitch-users at lists.freeswitch.org
Ämne: [Freeswitch-users] mod_rtmp audio codecs issues for speech recognition?

Hello,

I am trying the FS sample Flex client for TTS and speech recognition.
The TTS sounds OK. I use Nuance MRCP v1 server with Nuance recognizer 9.

The problem is that I hardly get the recognition result,only occasionally I got some simple words output like "repeat", "ok" which were not I said.
The whole recognition setup works well when I use a telephone line but basically not work by using the flex client from a web broswer.
The recorded voices in FS which were sent from the web browser via the flash rtmp sound fine.

I guess it may be the audio codec issues. The flash rtmp uses Speex. My mrcp profile specifies the codecs as "PCMU PCMA L16/96/8000"

Is there a way to automatically convert the Speex audio to the mrcp required formats during calling the system?
Or what should I look at to get the proper speech recognition via the flash rtmp?

Many thanks!

Xing



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