Re: Secure voice software issues

Can someone tell me how fast CELP is when written in C?
(On some particular machine.)

norm@netcom.com (Norman Hardy) writes:

>Can someone tell me how fast CELP is when written in C?
>(On some particular machine.)

Our CELP codec should run real-time in C on the Pentium and PowerPC.

By the way, note that GSM will not run with v.32bis asynchronously,
because of the start and stop bits.

	Miron

This was discussed a while back in the context of secure voice
hardware, but I don't remember whether anyone had been able to get
real-time CELP performance with any particular implementation.

I do know that ZyXEL's modems are able to do real-time CELP using a
68000 processor. The low-end models can do CELP encoding at 9600 baud,
and the faster ones do better-quality encoding (ACELP, I think they
call it) at 19200 baud.

The Mac OS also includes Apple's sound compression routines, which
aren't CELP (i.e. they're not optimized for voice) but allegedly can
do real-time compression.

-Paul

-- 
Paul Robichaux, KD4JZG     | "Crypto-anarchy means never having to say
perobich@ingr.com          |  you're sorry." - Tim May (tcmay@netcom.com)
Intergraph Federal Systems | Be a cryptography user- ask me how.

> I do know that ZyXEL's modems are able to do real-time CELP using a
> 68000 processor. The low-end models can do CELP encoding at 9600 baud,
> and the faster ones do better-quality encoding (ACELP, I think they
> call it) at 19200 baud.

I believe that there is a DSP of some kind in there in addition to the 68000.
Also, only their high end modems do CELP.  The regular 14.4/16.8 one doesnt't.