[vorbis-dev] PreBeta4/First Results

Dirk Knop dknop at gwdg.de
Wed Jan 24 00:57:56 PST 2001

Hi there,

I encoded the hard to encode piece ":wumpscut: - mother" with the new 
prebeta4 encoder (windows). As I crashed my harddrive I've to reinstall 
linsuxx again and double check the results, maybe there's a difference 
between the platforms (as far as I remember there was such a thing before).
This song is pretty good for fast listening-tests as there are plenty of 
"percussion-only" sequences with many effects like reverb, echo,... and 
there are distorted "church organs" and strings that make it difficult for 
every encoder to get the job done right ;o)

My results are:

-b 100: 111 kbps. sound quality is inacceptable, sounds a little like an 
old tape to me
-b 112: 104 kbps, sounds ok for the bitrate/full stereo
-b 128: 124 kbps, sounds a little "flat"
-b 160: 154 kbps, _much_ better, still a bit flat though
-b 192: 175 kbps, sound quality is good.
-b 256: 248 kbps, i can hear no improvement...
-b 350: 308 kbps, as well no improvement of sound quality

The quality seems to be better than in mp3, although it always sounds a 
little flat to me, I think the best description would be that the original 
(and mp3) have more "colours" (compared to <160 kbps vorbis). I was 
surprised that the 100kbps mode gave real bad quality at a higher real 
bitrate than the 112kbps-mode. This is the first mode that introduces a 
mp3-like "bubbling sound" that is not to ignore (112 kbps does this _a 
little_ as well at more silent passages). Modes higher than/equal to 128 
kbps sound really fine.
The encoder tripled in speed compared to beta3 on my duron 700.

I'm still waiting for the channel-coupling to compare the results to other 
formats in a fair way :)

I hope this helps you,

regards and thanks for this good work,


P.S.: if you want to verify my results there is still a ~7MB-piece of the 
first seconds of this song downloadable at 
http://roeder.goe.net/~koepi/hard_one_vorbis.zip (6.5MB)

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