Vorbis - Dec 2002 - docs question

hello,
i have a question about the documentation:

oggenc --help says:
 -b, --bitrate        Choose a nominal bitrate to encode at. Attempt
                      to encode at a bitrate averaging this. Takes an
                      argument in kbps. This uses the bitrate management
                      engine, and is not recommended for most users.
                      See -q, --quality for a better alternative.

while man oggenc says:
       -b n, --bitrate=n
              Sets  encoding  to  the  bitrate  closest  to n (in
              kb/s).
(nothing about the management engine)

and
       --managed
              Set bitrate management mode. [..]

does -b actually activate the bitrate managment mode as --help says or not (at
least the manpage does not mention it) and it has to be turned on manually?
i remeber reading somewhere that it has to be activated explicitely using
--managed, so the --help would be wrong then?

i hope i didn't post total nonsense right now as i am already confused
today ;)

btw:
# oggenc -v
OggEnc v1.0 (libvorbis 1.0)

<p>regards,
        wernfried


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Hello, 

my name is Christophe Leske and i have been on the Macromedia Director
QA team until march of this year before i quit.
Before i left, a sound engineer did me a favour and implemented the Ogg
Vorbis format as an asset Xtra. 

You can download it at
http://www.directordev.com/tools/xtras/OggVorbis/Ogg.htm

<p>I am more a multimedia developer than a real programmer, although i am
siffing through C# and C++ language definitions and listings for quite
some time now. If you got Lingo and Director related questions, just ask
me right away.

I would like to say that i like Ogg Vorbis very much, very cool project,
and the sound quality is just great...

I would like to see a pocketPC player for Ogg one day (i know about one
project that is currently in beta), and eventually take on the work on
the vorbis sound Xtra.

Christophe Leske
www.multimedial.de
www.director3d.de

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Haas Wernfried wrote:
> oggenc --help says:
>  -b, --bitrate        Choose a nominal bitrate to encode at. Attempt
> while man oggenc says:
>        -b n, --bitrate=n
>               Sets  encoding  to  the  bitrate  closest  to n (in
>               kb/s).
> and
>        --managed
>               Set bitrate management mode. [..]
Yes, since --help doesn't mention --managed, the help-text is obviously
wrong. It works like this:

In most cases, you want full, quality-based VBR mode. You choose your
quality with the -q switch, from -1 to 10. 
Every quality settings comes with a so-called "nominal bitrate", for
example 112 kbps is the nominal bitrate for -q 3. The problem with those
nominal bitrates is that they're no more than mere hints on where the
actual average bitrate of the encoded song _might_ end up. You can also
select the quality level based on the nominal bitrate, just don't be
surprised if some quite different bitrate comes out in the end - this is
still full VBR. E.g. if you choose -b 112, this would equal -q 3 on
44.1kHz/stereo input.

If you want to use average bitrate encoding, with the bitrate management
engine, you have to explicitly enable it with the --managed switch.
--managed requires the -b switch, as we care about bitrates now. oggenc
-b 112 --managed file.wav would encode file.wav with bitrate management
and the goal of having a ~112kbps file in the end. Using bitrate
management comes at the cost of lower quality and much longer encoding
times, what you gain is more predictable file sizes.

<p>Moritz
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