[Vorbis] Bit rates, files size

[Haxe]

On Wednesday 29 September 2004 01:28, Rodrigo Escobar Nunes wrote:
> OK, I got the idea about bit rate, and I understand that it can't be
> compared across formats. So, the big question now is, is there a way
> to compare the results? Lets think of something like creating
> different music files, and comparing them back to the original
> DIGITALLY; can you calculate in any way which file is closer to the
> original? BTW, is this a good indication of sound quality (a MP3
> might for instance catch ALL the silence perfectly, thereby being
> "closer" to the original in some way, even if it does not render a
> good sound...)? How about dividing the analysis into different
> frequency levels?
>
> Its not that difficult to imagine a way, its just the goode-ole
> square differences.

No, there is absolutely no way to compare the audible quality of two 
encoders "digitally".

Of course, you can invent some model of how the human ear might "feel" 
the difference, may it be square differences or anything else, but that 
doesn't mean that your model even remotely tells the truth about 
audible quality.

Other mathematical models have been invented before. One model is used 
in MP3 to get the highest possible "quality" (in terms of that model) 
with the least possible bits. Vorbis uses another model of measuring 
"quality". And your sqare difference may be a third model.

But to tell how good a certain model reflects what the ear really feels, 
there is NO other way than to ask lots of careful listeners in a 
double-blind test.