[vorbis] nominal bitrates

[Mark Hetherington]

I just tested some music at 8kbps, with oggenc -q -1 --downmix --resample 
8000, and I must say, even though it was obviously lacking in quality, it 
wasn't completely unbearable as I was expecting it might be. Speech was 
clearly recognisable, all the instruments were there. Does anyone know of a 
cross platform (specifically windows and linux) voice telephony program using 
ogg? I'm thinking about writing a quick and dirty utility to just pipe ogg 
out over to another person for voice telephony, because even at 8kbps voice 
seems to be well represented (this would save me heaps on long distance!!!).

I think I'll run some tests, because I was really impressed with my quick 
listen.

Mark

On Sat, 27 Jul 2002 00:09, Moritz Grimm wrote:
> Hi,
>
>
> apparently, I didn't delete my test samples ... I found them. :) Here's
> a small table of what nominal bitrate fits to which quality at what
> sample rate. Quality levels inbetween -1 and 0 are possible, but I
> didn't test them. Nominal bitrates of those quality settings will be
> somewhere between those of -1 and 0 and therefore can be guessed.
>
> q/channels ||  -1/mono | -1/stereo ||  0/mono  | 0/stereo
>  samp.rate ||          |           ||          |
> -----------++----------+-----------++----------+-----------
>    8000 Hz ||   8 kbps |   12 kbps ||  14 kbps |  18 kbps
>   11025 Hz ||  12 kbps |   16 kbps ||  20 kbps |  26 kbps
>   22050 Hz ||  16 kbps |   30 kbps ||  24 kbps |  36 kbps
>   44100 Hz ||  32 kbps |   48 kbps ||  48 kbps |  64 kbps
> -----------++----------+-----------++----------+-----------
>
> 32000 Hz sample rate is also a tuned set of modes, but doesn't give much
> advantage over 44.1 kHz at those quality settings in terms of filesize.
> I didn't make 32kHz test samples either, so this is an exercise for the
> reader. :)
>
> Note that on some clips, the average bitrate was very close to the
> nominal bitrate, in some it wasn't at all. Nevertheless, those nominal
> bitrates should show which --managed settings are supposed to work well
> with a certain sample rate.
>
>
>
> Moritz
>
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