[vorbis] Question, problems re: Ogg Vorbis ..

[Aleksandar Dovnikovic]

"Thomas Kirk" <thomas at arkena.com> wrote:

> > Finally, check this message that David McIntyre (he works for QDesign)
> > wrote on artifacts some time ago on mp3.com message board - it is a
> > good starting point because it explains most common types of artifacts:
>
> You think it would be legal to post this message on another site?

Sure, no problem.

> is this why windows media audio codec tend to sound warmer but has a
> really big problem with pre-echo even on high bitrates?

Yes. That's why some other codecs like AAC have almost no pre-echo
in lower bitrates (128, 160) but the codec sounds more brittle and
artifical.

> > Other time resolution problems: other than pre-echo the most noticeable
> > is the watery sound many codecs get, particularly on voice. This has to
> > do with insufficient time resolution on the rich harmonic content in the
> > vocal spectrum.
>
> again the same problem windows media audio codec has?

Yep.

> you have more links,docs whatever on this topic? I wanna read more :)

Well I don't have more links on the 'artifacts' topic, but you can check
the following links for explanations on how lossy audio codecs work
- can be quite interesting (ignore some formulas) - for example, did
you know that there is a thing called temporal pre-masking, which
actually means that one sound can mask another one that appeared
before him ?! Looks a bit illogical, but there it is... :-)

If you ignore the mathematics, this site can be a good read on some
basics in audio compression:
http://www-ccrma.stanford.edu/~bosse/proj/proj.html

For info on how MPEG 4 Natural Audio works (current state-of-the-art
in lossy audio compression) and what tools are used in this format, check
out:
www.cselt.it/leonardo/icjfiles/mpeg-4_si/9-natural_audio_paper/index.html

Greetings,
Aleksandar

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