[Freeswitch-dev] VAD, TALK and NOTALK events

[Steve Underwood]

Brian West wrote:
> On Feb 18, 2008, at 6:55 PM, Steve Underwood wrote:
>
>   
>> There is a pretty good free echo canceller at www.rowetel.com,  
>> although
>> FreeSwitch can't directly use it as it is GPL software. It does,
>> however, mean that free and open workable algorithms for robust EC  
>> do exist.
>>
>> VAD is different. It is still a research topic. You can see this from
>> the way the VAD algorithms in things like G.729 have been revised over
>> the codec's lifetime, as further research has been done. The  
>> algorithms
>> G.729 and AMR use are encumbered by patents, otherwise cloning them
>> would be excellent start. VAD for speech recognition is relatively
>> straightforward. When you can buffer the audio, and look forwards and
>> backwards in time, it become much easier to identify the start and end
>> of voice bursts. It becomes hard when you can only look back in a low
>> latency scenario.
>>
>> Steve
>>     
>
> Isn't that Echo canceler live in Kernel space?  If so then its fine.
>   
That's why I said "directly" use it. I don't know what you guys intend 
to do about openzap drivers.

Steve