I have run an ogg analisis using EAQUAL from -q 0 till
-q 10 evaluating bitrate and quality. The results are
shown in a nice graph, and can be seen here:
http://audio.sinderman.com/
One thing I have found is a bug, as it is cleary shown
by the blue lines. Other discoveries are written in that
page, and others are still evolving in my mind :)
The goals of this analisis is to help the developers
(if this is help at all for them), an to help people decide
which -q is most suitable for them.
But I have some more questions:
1) RC3 files can be peeled. Is peelability going to further improved?
2) Is there a cost for peeling instead of encoding directly with lower
quality? I now is less than reencoding but, is negletable?
3) What happens with a file encoded with lossless channel coupling when
it is peeled to a quality with lossy coupling?
4) Can next version (I understand there will be a kind of RC3b before RC4
with the -b removed) have a (hidden?) option for turning on lossless channel
coupling at different q values for testing?
5) We are trying to educate people to think in quality terms instead of
bitrate. But q 5 for most of the world means nothing, and 128 or 256 quiet
a lot. Shouldn't we do ie as Microsoft decided (probably after spending
millions of dollars in research :) to make it (also) as simple as "radio
quality" "almost CD quality" "CD quality" etc?
6) What about an idependent codec table comparison? Because if we take 5)
and said -q 6 is almost CD quality when Microsoft comes with its shitty
codec claiming also almost CD quality with half of the size will not be
fair. A common messurement of CD (and others) quality should be used.
EAQUAL? Eventhough it is prune to errors, it is independent :), and as an
average comparison sould be quiet secure.
7) What about building a FAQ? :) (Developers please ignore, you have other
priorities) I talk exclusively to frecuent people in the lists. Any
volunteers? I have seen some questions coming once and again all the time.
I hope I am not one of those :)
8) I would like to know also what do you think about the issues I have
rised in the URL mentioned above. Or if the graph is showing anyone further
facts.
9) Do you think further graphs could be useful for developers/users? I am
open for comments.
<p> Well, thats all. Too long for my forst post.
Cheers, AGS.
<p>--- >8 ----
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Gian-Carlo Pascutto
2002-Jan-16 10:07 UTC
[vorbis] Ogg Vorbis Quality Analisis (+ bug) (+ misc)
----- Original Message ----- From: "AGS" <sound_AT_sinderman.com@spamm.off> To: <vorbis@xiph.org> Sent: Wednesday, January 16, 2002 6:22 PM Subject: [vorbis] Ogg Vorbis Quality Analisis (+ bug) (+ misc) <p>> One thing I have found is a bug, as it is cleary shown> by the blue lines.Hmm, you mention you couldn't hear any difference even at -q0 with that file, so it could also be that Ogg can encode it perfectly with a minimal amount of bits :)> 1) RC3 files can be peeled. Is peelability going to further improved?I'm confused about this. I thought RC3 was supposed to be peelable, but there was a mail from Monty a few hours ago claiming they were not. As far as I understand, peeling is equal to encoding at a lower bitrate. i.e. no quality loss.> A common messurement of CD (and others) quality should be used. > EAQUAL? Eventhough it is prune to errors, it is independent :), and as an > average comparison sould be quiet secure.EAQUAL is principally flawed for doing comparisons between different codecs. There was a long (7 pages) and heated thread about this on HA. Link: http://www.hydrogenaudio.org/forums/showthread.php?s=&threadid=712&perpage=2 5&pagenumber=1 -- GCP <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
On Wed, 16 Jan 2002, AGS wrote:> I have run an ogg analisis using EAQUAL from -q 0 till > -q 10 evaluating bitrate and quality. The results are > shown in a nice graph, and can be seen here: > http://audio.sinderman.com/Eh.. all I get is a redirect to http://www.xiph.org/archives/vorbis/index.html -Dan -- [-] Omae no subete no kichi wa ore no mono da. [-] <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.