I'm building a voip application. Most of it works, but I'm missing facilities for detection of tones e.g dtmf or voicemail beeps. Normally a dsp should do the job, but the telephony system used has no dsp's onboard. The Goertzel algorithm can be used to implement the logic needed.
The application has to be a dll which takes an audio buffer (alaw 8khz mono, without header (raw)), this buffer is populated by some third party software. Other arguments are : frequency(s) to detect and a time indicator (how long on a tone has to occur e.g. 100ms). When the specified tones have been detected a callback has to be done indicating which tones have been found.
The application should be robust and fast. It should be able to handle 750 concurrent calls if needed on a 3ghz dual core system with 2gb of ram. For now it will handle 4 lines, as a proof of concept.
Any suggestions appreciated.
Delivery of both a dll and the source code preferably in a ms visual studio project.
With best regards