[Vorbis] Bit rates, files size

[Giuliano Pochini]

On 28-Sep-2004 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?

Yes, you can. It is called spycoacoustic model. But it's not perfect
at all, and it can't be so. That model is used to estimate what
parts of the sound are less audible, so the encoder can reduce the
resolution (or remove) that parts in order to save space. It can't
be perfect because the model should also depends on factors that are
not available at encoding time. The major ones are the playback
volume and the actual model of *your* ears (which may change with
training and over time).


> Its not that difficult to imagine a way, its just the goode-ole
> square differences.

No, don't waste you time with that one. The human p-a model depends
heavily on the frequency and time domains.


--
Giuliano.