[vorbis] Quality & Tags

[Moritz Grimm]

Alexander Poquet wrote:
> QUALITY=<number>
> 
> Hope some of you agree.

I absolutely agree, although we don't "really" need a quality tag. The
nominal bitrate already shows roughly what quality level has been used,
e.g. 160032 (160kbps) for q5, 80kbps for q1, etcetc. More important than
that is whether bitrate management has been used or not.

I'd rather go for something like an ENCSETTINGS tag or whatever (let's
fight over that for 2 months, please :) ) and put the quality related
commandline parameters in that. (E.g. ENCSETTINGS=-b 96 -M 105,
ENCSETTINGS=-q 3.45, ...) It shouldn't be too difficult for encoders
with graphical interfaces to figure out what commandline would have been
used.

Its advantages are that it's short, readable to humans that know oggenc,
it CAN be used by players to form more human readable sentences like
those from the next example in any language. Not so good about it is
that it's not "really" human readable ... it's knowledge about
commandline parameters that has to be there to be able to understand it,
and no player exists that would create nice sentences, yet (and support
for it can take quite a while).

Another suggestion would be to make it very human readable, to let the
encoder puzzle together valid sentences. Stuff like that:

ENCODED_USING=[ True VBR | Managed bitrates ] at [ quality level <n> |
<n> kilobits ] [ . | , limited to [ max. <n> kbps ] [ . | (and) min. <n>
kbps. ] ]

D'uh, does that make sense to anyone? I think this is far from proper
BNF ... ;)

The advantage of the big human readable thing is that those users who
never touch the command prompt would know what the fuzz is all about.
What I don't like about it is that this long sentence makes it pretty
exhausting if you feel like going through a whole bunch of Ogg files. A
less pretty but maybe more readable version would be something like

ENCODED_USING=[ True VBR | Managed bitrates ] (ENCSETTINGS)

This means I'd put the encoding parameters fom idea number 1 in brackets
behind the mode.

Idea number 2 and 3 have both the disadvantage that they're always in
English. I don't really care about it, because I understand it. :) If
this should be a major problem for some people, I'd still suggest idea
number 1, i.e. an ENCSETTINGS compatible tag.

In a second thought, I'd go for ENCSETTINGS myself - this would be the
most flexible and easy solution. We don't have an 1.0 release, so
ironing out all scary technical things for the dumb user market
shouldn't be a top priority yet.

<p>Moritz


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