[vorbis] Difficult sample for vorbis w/ audible artifacts

[Wilson]

I'll drive to work and get my Sennheisers.

----- Original Message -----
From: "Darin Morrison" <dibrom at moscow.com>
To: <vorbis at xiph.org>
Sent: Friday, June 15, 2001 11:00 PM
Subject: Re: [vorbis] Difficult sample for vorbis w/ audible artifacts

> > I grabbed the WAV, and encoded it with the latest Oggdrop at 350kbps. I
> > dragged 5 instances of the WAV file, and 5 instances of the Ogg file
into
> a
> > Winamp playlist, and randomized it. I don't hear any artifacts in the
Ogg
> > file..
> > Next, I encoded the WAV file to a 128kbit VBR MP3 with RazorLame, and
into
> a
> > 128kbit Ogg file with Oggdrop 1.0b4. I put three instances of each into
a
> > Winamp playlist, and 3 instances of the WAV file. Hit randomize, turned
up
> > the volume, closed my eyes, hit play. I really don't hear any artifacts.
> > Admittedly, I'm using Klipsch Promedia 4.1s.. Not reference quality
stuff.
> I
> > left my Sennheisers at work today.. I get the impression from your
message
> > that it's not supposed to be that subtle.
> > If it would help, I could make my mp3 and ogg test tracks available to
> you..
> >
>
> I should have probably clarified this in the original message, but the
> artifacts in question are harder to hear on a stereo system than on
> headphones.  I don't have the best set of headphones (Sony MDR-V600's,
plan
> on getting some Sennheisers or Grado's soon) but I can hear them very
> clearly.  I do have a harder time hearing them, at least with vorbis, on
my
> midrange Sirocco Pro system though but there's no question they are
> definitely there. I could pick the vorbis encoded samples out of an abx
test
> 16/16 times with absolutely no problem.  If you follow the last link in my
> original message there's quite a bit of discussion about the artifact
> already, I'd rather not retype everything I already have.  Here's the meat
> of it at least:
>
> "Just tested the clip with vorbis beta4.  Heres what I found.
>
> This clip tested initially with oggenc -b 256 (~226) sounds *much* better
> than LAME/--r3mix.  I was actually quite surprised.  Almost all of the
> annoying errors are gone.  However, I did try listening with an abx test
and
> I was able to pick it 16 out of 16 times.  There seems to be another
> artifact with vorbis that I don't hear with --r3mix.  Right at the end of
> the bass note, or "fart" as ff123 put it, there is a little humming
sound..
> like a bit of added resonance or something.  It took me a few tries to
> distinguish it but once I had I was able to pick it out of the abx every
> single time.  In my opinion though this is a far less annoying artifact
than
> with LAME.
>
> I also tried with oggenc -b 180 (~186) to be more "fair" to --r3mix.  It
> actually sounds quite a bit worse than with -b 256.  The bass note is alot
> "noisier" and there is a very obvious pre-echo during the start of the
"zip"
> sounds.  However, with both settings with vorbis, I don't hear the tapping
> sounds overlaid upon the "zips" like I do with mp3.  The attacks don't
seem
> as sharp as the .wav or with mpc still though"
>
> Anyway, I could understand maybe not hearing the distortion on the bass
> note, but the pre-echo artifact, especially at lower bitrates, is very
> obvious.
>
> Dibrom
>
>
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