I would be interested in wideband codec2. Does it sound much better when
you use normal voice (I am not much of an opera singer anway ;)?
Is the bitrate doubled? Is it more CPU heavy?
Stuart Marsden
On Feb 7, 2012 8:42 AM, "Rick van Rein" <[email protected]> wrote:
> Hello Peter,
>
> Wow, great work!
>
> > Codec2 in the 1400bps mode operates on audio in chunks of 40ms.
> > However, the modem implementation uses powers-of-2 (a reasonable thing
> > to do with FFTs), which results in a symbol period of 12ms.
>
> I've been working on a "wideband Codec2" that uses the FFT at a
> power of two by choosing a sample rate of 12.8 kHz, leading to
> an FFT over 512 elements. The wonderful thing about Codec2 is
> that it is fully agnostic to sample frequency, so you would end
> up sending the same frames, although possibly with harmonics
> that won't be played at the other end -- unless they also use
> your soundcard implementation. A shorter symbol period would
> mean a change of protocol; going widebind means that you can
> make a local choice.
>
> I've done only rough tests with this codec, but it would seem to
> work. Let me know if you would like a copy. I still need to
> sample children's voices to see if they run over 600 Hz. What
> I have done is sample an opera-singing lady (which is not fair,
> the codec isn't designed for that) and she ends up sounding
> like a toad (no phantom of the opera needed here) because her
> 1 kHz voice is not sought for, and other frequencies are
> recognised as the apparent base tone.
>
> If people on the list want to see the code, or hear the toad,
> I can put it online. The lady is so far off after Codec2 is
> done with her that this is not copyright infringement ;-)
>
>
> David: all this derivative work... must be a sign that you're
> on to something very good :-)
>
>
> Cheers,
> -Rick
>
>
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