[vorbis-dev] PreBeta4/First Results

Dirk Knop
Wed, 24 Jan 2001 00:57:56 -0000

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,

Dirk

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)