[Ground-station] FreeDV QSO party, FreeDV GUI as a starting point for P4G?

[Michelle Thompson]

6 kb/s isn't really where I'm looking at for us. We need something more
like 20 kb/s. The 6kb/s choices still sound bad to me. It's just still an
inferior experience at 6 kb/s.

I think WhatsApp uses something on the order of 26 kb/s. You can clearly
hear the other person, immediately recognize their voice, and speak with
them for hours without any fatigue. That's what we should be enabling or
even providing in a reference design or reference application.

Opus at 20 kHz bandwidth (I think it's their 40+ kHz sampling rate) might
fit the bill. If Opus had something higher, then that's even better.

-Michelle W5NYV




On Mon, Feb 25, 2019 at 1:51 PM Phil Karn <karn at ka9q.net> wrote:
>
> On 2/24/19 09:18, Michelle Thompson wrote:
>
> > Neither codec2 or opus sound great, even at high rates. I really like
> > the high rate aac used by WhatsApp. That's the minimum quality we should
> > be delivering.
>
> Opus has a minimum bit rate of 6 kb/s (though I think it may have
> recently been dropped to 5). It definitely outperforms AAC in subjective
> listening tests at the same bit rate, and best of all it is completely
free.
>
> Because all these codecs (including Codec2) can operate at variable bit
> rates, I recommend supporting them. Stations with bigger transmitters
> and/or antennas should have the option to run at higher bit rates.
> Obviously there may be a least-common-denominator problem with receive
> stations, but I think the feature should be there.
>
> You need not support a super fine grained choice of bit rates, but there
> should at least be a choice.
>
> Phil
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