Vorbis dev - Jul 2003 - oggenc questions

Hello everybody!
Some questions concerning oggenc:
1 why is it called oggenc? (vorbisenc would make more sense)
2 Is it true, that oggenc uses only some predefined codebooks (depending on -q)?
2.1 Are they just "random" books, or were they "optimized"
in any way
2.2 Is it possible, that some codebooks are stored in the header, but are never
used (even in long (>3min) files)?
4 Are there any docs about the psychoacoustic model?
5 Does it compress using two passes (whole file)?
5.1 Is it necessary to use twopass to do "real" VBR (1. pass: estimate
BR; 2.pass: compress)?
 (ups, this is a general question about VBR)
5.2 Same applies to windowsizes: It has to check the file before choosing
optimal windowsizes

Another question that has nothing to do with oggenc:
Are there any compliance test Ogg Vorbis files?
Or any boundary test files (eg:
  -full dynamic range
  -large codebooks
  -plenty of comments)?

<p>Thank you for any informations
Dominik

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On Sun, 2003-07-27 at 15:58, Dominik Kuhlen wrote:
> 1 why is it called oggenc? (vorbisenc would make more sense)
No idea.  oggenc was shorter probably.  :)  We've talked about this
issue, but haven't reached a consensus beyond "leave it unless we have
a
compelling reason to switch".
> 2 Is it true, that oggenc uses only some predefined codebooks (depending on
-q)?
Yes, they are predefined.  (Keep in mind most of the answers here apply
to the reference vorbis encoding libraries, which nearly every tool
uses.)
> 2.1 Are they just "random" books, or were they
"optimized" in any way
They are optimized, though this is somewhat of a black art.
> 2.2 Is it possible, that some codebooks are stored in the header, but are
never used (even in long (>3min) files)?
I don't think so, but I don't know the answer for this one for sure.

<p>> 4 Are there any docs about the psychoacoustic model?

The specs here:

http://www.xiph.org/ogg/vorbis/docs.html

mainly regard decoding.  I don't know of any precise documentation of
the psych model used.
> 5 Does it compress using two passes (whole file)?
No.
> 5.1 Is it necessary to use twopass to do "real" VBR (1. pass:
estimate BR; 2.pass: compress)?
>  (ups, this is a general question about VBR)
> 5.2 Same applies to windowsizes: It has to check the file before choosing
optimal windowsizes
Because of the previous answer, these are also no.  The standard
encoding libraries do single pass VBR.


---
Stan Seibert

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