[vorbis] Quality & Tags

[Moritz Grimm]

fungus wrote:
> > What if your friend encoded LOTS of files and doesn't remember whether
> > he used managed bitrates or not, for example?
> Why would anybody be using managed bitrates?
> I thought we were trying to get away from that.

I know. Right now, one can't distinguish true VBR Ogg files from managed
ones. Being able to do so can help to track down the "wrong" Ogg files
and people can "teach" those who didn't know about the lesser quality in
managed Ogg files. That tag is also good to learn more about streams
that were ripped to disk. bitrate_upper and bitrate_lower already tells
us whether an Ogg file has boundaries, but whether we got managed or
true VBR is unknown (at least after RC4). We either need another tag
called "true_vbr=true | false", or "managed=false | true" or we get
something like encsettings that sums up all the details.

"encsettings" & co has the advantage that we could divert attention from
the bitrate_* tags. bitrate_nominal can give a hint on what -q setting
was used, but it obviously has the strongest relation to bitrates in
general. Streaming applications depend on bitrates, so deprecating (and
by that possibly breaking decoders) bitrate_* would be a bad idea.

<p>Moritz


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