[vorbis] Using oggenc

[Graham Mitchell]

> I wanted to ask some experienced users some settings about oggenc.
> 1. How can I setup oggenc so that I can DIRECTLY rip tracks off my audio
> cd? As we all know, audio cd doens't really have a file format that we can
> directly use. Do I HAVE to convert them to wav files then convert them to
> ogg files?

Well, you pretty much *have* to get the data into something approximating WAV 
format, though that doesn't have to be written to disk.

oggenc doesn't handle ripping from CD.  If you're in Windows you'll want to 
use EAC or CDex, since they both support "on-the-fly" Ogg Vorbis encoding.  
You can find links for downloading these "rippers" at ogghelp.com:
        http://www.ogghelp.com/ogg/downloads.cfm

Under Linux, there's a way to feed oggenc directly from a pipe from 
cdparanoia.

> 2. The options: -b -m -M with the bitrate of the audio file. If I set
> something with the '-b' option and also use the '-m' and '-M' option, for
> example 'oggenc -b 128 -m 64 -M 128 file.wav', how is this effected?

You almost certainly don't want to do this.  Ogg Vorbis is natively a VBR 
format, and thus specifying a specific bitrate forces it into a pseudo-CBR 
mode, which will *always* produce worse-sounding files at a given filesize.

> Furthermore, how does the '-q' option come into role here? It says that it
> ranges from 0 to 10. I'm assuming that this is a preset quality controller
> that we can use to replace using the other three options that I previously
> mentioned. Is my assumption correct?

Yes, but unless you have very specific maximum bitrate needs (i.e. streaming 
to modem users), you should ALWAYS use -q alone and NEVER use -b, -m or -M.

In case you're curious, here are the average bitrates for each quality level, 
but keep in mind that the actual bitrate for a given quality level varies 
depending on the input file.  Also, note that these are simply estimates, 
oggenc doesn't actually aim at a specific bitrate at all.  The quality 
setting is a measure of "closeness to the original" which is used internally, 
and the resulting bitrate (whatever it ends up being) is a byproduct of that.

        Quality -1		~48 kbps
        Quality 0		~64 kbps
        Quality 1		~80 kbps
        Quality 2		~96 kbps
        Quality 3		~112 kbps
        Quality 4		~128 kbps
        Quality 5		~160 kbps
        Quality 6		~192 kbps
        Quality 7		~224 kbps
            ...etc
        Quality 10		~498! kbps

For more clarification on this you might want to read the section on "CBR? 
VBR? ABR?" and the following section on "Just Say No To Bitrates" in the 
Introduction to Compressed Audio with Ogg Vorbis (by yours truly) at:
        http://grahammitchell.com/writings/vorbis_intro.html


-- 
Graham Mitchell - computer science teacher, Leander High School
"There has grown up in the minds of certain groups in this country the notion
that because a man or corporation has made a profit out of the public for a
number of years, the government and the courts are charged with the duty of
guaranteeing such profit in the future, even in the face of changing
circumstances and contrary to public interest. This strange doctrine is not
supported by statute or common law. Neither individuals nor corporations have
any right to come into court and ask that the clock of history be stopped, or
turned back."
	-- Robert Heinlein, "Life-Line"

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