[vorbis-dev] Audo quality problem

[Graham Mitchell]

> sounds/music, but certain pieces of synthesized music (specially techno)
> contained very audible artifacts even at high bitrates.

I listened to your samples, and couldn't ABX them even with my $150 
headphones on.  By subtracting the WAVs from each other, I can hear what 
you're probably talking about, but I'd say "very audible artifacts" is 
perhaps a little overstated.

Secondly, for someone with golden ears like yourself, I wouldn't consider q5 
to be "high bitrate".

If you're unhappy with Vorbis' performance on a particular track at a certain 
bitrate, then keep encoding with higher bitrates until you can't hear the 
difference.  You may be running into the known "treble boost" artifacts at 
bitrates under q6 or 7.

It might be helpful if you could determin the lowest quality setting where 
the problem (for you) goes away.  Say, within .5 or so.

You also might be interested in the Garf-tuned version, which gives higher 
quality at some of the higher bitrates than stock oggenc does.  Search the 
archives for a link.

That said, we are always looking for hard-to-encode samples to help us reduce 
artifacts, and it may turn out that a slight modification can be made to 
Vorbis to help reduce such artifacts for future versions.  I'll let any 
developers address that.

Also, thank you for going to the trouble to put up FLACs containing just the 
short sample where the artifacts occur, as well as descriptions for what 
you're hearing.  It certainly makes your complaints easier to assess.


-- 
Graham Mitchell - computer science teacher, Leander High School
"Several tiers below the surface [of the human heart] is a pervasive,
integral force that demands the right to avoid pain and experience
self-fulfillment.  This self-centered energy is the very essence of
what the Bible calls 'sin.'"
	-- Harry Schaumberg, "False Intimacy"
--- >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-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.