[Vorbis] very low bandwidth encoding

[Geoff Shang]

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.