[Speex-dev] Suitability of speex for use with noisy, non-voice source material?

david feldman wb0gaz at hotmail.com
Sun Apr 27 09:27:25 PDT 2008

Question from new subscriber -

I'm working on a project to connect to remotely connect to a short-wave receiver via a dial-up PPP/IP circuit. Turns out the dial-up circuit is only stable (useful) to 14.4 kbps (faster modem training produces so many link errors that the net circuit quality is unusable - one end is in a remote, rural location), so looking for codec that can fit within this circuit minus PPP/IP overhead (probably 10 kbps net based on testing so far.) Latency is a consideration so I'm looking at voice-type encoding vs. streaming MP3. I was going to try use of G726 but it's not configured below 16 kbps so hence my resumed search for a codec.

In my initial searching I found speex, but before I try to engineer the solution, I'd like to get any advice on use of speex in with the expected source material, which is likely to be noisy (static and stuff mixed in with the source audio). The source audio (monaural) will be pre-filtered to fit with 300-3000 Hz passband (can be slightly narrower if need be), and may not always be a single voice (that is, may be>1 voices interfering with the audio passband, or even non-voice such as tones and other stuff that would appear in the passband of the receiver.) So based on this, would I want to avoid speex or proceed to experimentation? By the way, this is just for a personal project, no commercial intent.

Very tks,

wb0gaz at hotmail.com

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