Vorbis - Sep 2004 - very low bandwidth encoding

I'm trying to encode audio tracks as ogg vorbis at very low bandwidths for
peer to peer broadcasting. I.e. need to have two streams uploading from
modem users, which means the bitrate needs to be around 18-22 kbps.

It's not easy to get good quality at this bitrate. The recipe I'm using
at
the moment is:

 oggenc Mon-Sep-20-04-0\:3\:27.wav -b 20 -M 22 --resample 17000 --downmix
 -o test.ogg

which is OK, but still has a tinny sound with some tracks.

If anyone knows how to get good sound at this bitrate, I would appreciate
some advice. e.g. any preprocessing that's worth doing.

Andy Baxter wrote:
> I'm trying to encode audio tracks as ogg vorbis at very low bandwidths
for
> peer to peer broadcasting. I.e. need to have two streams uploading from
> modem users, which means the bitrate needs to be around 18-22 kbps.
Note that unless you're using modems with V.90, modems can only uplink at 
33.6 kbps, so you'll need a rate of less than 16 kbps if you want to be 
able to up two at once.
> It's not easy to get good quality at this bitrate. The recipe I'm
using at
> the moment is:
>
> oggenc Mon-Sep-20-04-0\:3\:27.wav -b 20 -M 22 --resample 17000 --downmix
> -o test.ogg
>
> which is OK, but still has a tinny sound with some tracks.
Not sure if you need to use --maanaged to get those constraints to take 
effect.  But I'dve thought that something like -q -1 would be more 
effective anyway. Any reason you've not gone with 16kHz?

Geoff.