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> > I suggest you look at some of the freely available CELP codecs. They are
> > very forgiving and work at low bit rates. [No doubt that both properties
> > relate to the fact that these codecs have been developed by the US
> > Department of Defense :-] The major drawback of the CELP codecs is that
> > they require more CPU power. But the HLB should have enough.
> I don't think so, or you must know something that I don't. The CELP codecs
> I found couldn't do realtime on a 486DX4-100. More like 10% of realtime.
> You need pretty cool DSP to keep up with that. Neat codecs though. Sounded
> amazing still at 7200bps.
Our HLB uses a 30MHz/32-bit risc-cpu. This gives us about 25 Mips, i expect.
Standard-gsm needs about 10Mips (full-duplex), crypto needs about 5 Mips.
Let's have 5 Mips for everything remaining - then we use about 20 Mips.
So there is not much room left to complicate things...
It's not that we could not build an even more powerful HLB-hardware ;-)
But this would make it much more complex/expensive and should be avoided !!!
We would probably have to use 'real DSPs' again.
Does CELP usually need fixed or floating-point arithmetic ?
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