Vorbis dev - Sep 2002 - Vorbis is low on artifacts but EQ isn't good

I'm amazed by how low the artifacts are when encoding with Vorbis, but I
found
problems (Vorbis version 1.00) on equalization (high vs midrange vs low pitches
balance) when encoding my benchmark audio track, problems which are hard to go
away even at very high bitrates.

My benchmark audio track is composed by me and you can find it here
http://www.trombettworks.com/drumswork.php
in losslessly compressed version

Please have a look at the problem (also documented in that page).

The track is composed with an Alesis S4 synthesizer which is known for its very
sharp and harsh sounds which put lossy compressors in trouble. This piece in
particular is really hard to compress with lossy encoders and I always use it
for benchmark because it generates the most evident artifacts and equalization
problems I've found.

If you wish to use the track as a benchmark yourself for Vorbis development,
feel free to do so of course: I would be glad to help. If you wish to upload it
somewhere for Vorbis purposes / codecs comparisons / etc., do that.

<p>Best regards
Gabriele

PS: If you want to contact me directly, please use the email at the site, not
this one.
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Gabriele,
> I'm amazed by how low the artifacts are when encoding with Vorbis, but
I found
> problems (Vorbis version 1.00) on equalization (high vs midrange vs low
pitches
> balance) when encoding my benchmark audio track, problems which are hard to
go
> away even at very high bitrates.
I just reported a similar problem on the vorbis@xiph.org list
yesterday -- they could well be related. As I understand it, it has to
do with the fact that at high frequencies, oggenc doesn't separate the
two channels to save bandwidth, but this can lead to a change in
coherence and therefore a maximum +3dB change in total power in the
worst case of a 90deg phase difference in the original.

Any experts, please correct me if I'm wrong...

  Andras

==========================================================================Major
Andras
    e-mail: andras@users.sourceforge.net
    www:    http://andras.webhop.org/
==========================================================================---
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> My benchmark audio track is composed by me and you can find it here
> http://www.trombettworks.com/drumswork.php
> in losslessly compressed version
I forgot to mention that it's a self extracting Windows RAR archive. Under
Linux
I THINK the freeware Unrar should be able to decompress it even if it's an
exe
self extracting format. I have just put a link in the page for downloading the
Unrar for Linux.

Thanks Conrad for pointing out the problem.

I don't have Linux so I can't test the thing... Can anybody with Linux
check if
the unrar I have uploaded will work on the archive?

Thanks
Gabriele
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ons 2002-09-04 klockan 00.55 skrev MiwongShaib:
> 
> My benchmark audio track is composed by me and you can find it here
> http://www.trombettworks.com/drumswork.php
> in losslessly compressed version
> 
rar is very good at compressing audio files, but not as good as
specialized lossless audio compression codecs such as for example flac
http://flac.sf.net/. Flac is also free software, which rar is not.

[noa@ulysses slask]$ du -a Dru*
4       Drumswork Copyright.txt
12464   DrumsworkLossless.exe
11084   DrumsworkLossless.flac
18724   DrumsworkLossless.wav

<p>cheers/noa

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