[Vorbis] Bit rates, files size

[Haxe]

On Tuesday 28 September 2004 05:32, Rodrigo Escobar Nunes wrote:
> Does anybody has any idea how to compare mp3, wma and ogg in terms of
> bit rate and quality?

Hi,
Since Vorbis uses newer encoding technologies, Vorbis is much more 
efficient than mp3. That means, if you have an ogg file (with vorbis 
codec) and an mp3 file with the same bitrate, the ogg file will have 
much better quality. And if you try to set mp3 and ogg to the same 
"quality" (however you achieve this), the resulting ogg file will be 
significantly smaller.

It is hard (and somewhat unscientific) to express that with numbers, 
since it depends strongly on your mp3 encoder, the material you are 
encoding and on your ears. But my personal impression is that an 
OggVorbis file at 128 kbit/s may be comparable to an mp3 with
192 kbit/s.

> I mean, I have tested it and the ogg files are 
> always smaller if you set the same bit rate as compared to the other
> two, and smaller still if u use VBR.

With Vorbis, you normally don't use a bitrate setting when you are 
encoding. Instead, you use a fixed "quality" (use the -q option in 
oggenc, not -b and not --managed). This is what Vorbis really likes. 
All the other bitrate management staff is a little inaccurate (i.e. 
produces files of not exactly the requested bitrate, which is what you 
described above) and should normally not be needed.

If you set a fixed quality, for example -q 4, all the files you encode 
with this setting will have the same audible quality. This will result 
in some files having higher bitrates, if their content is hard to 
encode, and other files having lower bitrates, if their content is 
easier to encode. This is a really good feature.

Of course, this comparison only applies to ogg vs. mp3. I can't tell 
anything about wma.
Haxe