[vorbis] VBR vs ABR

[Graham Mitchell]

> It seems I have the choice between 
> VBR and ABR formatted oggs.  I am familiar with VBR (variable bit 
> rate) but not sure what ABR stands for?

ABR stands for "average bit rate", which is essentially a constant bit rate,
but using a bit reservoir.

> Is it possible/desirable to specify a bit rate when encoding oggs, 
> or does the nature of the ogg format make use of varying bit rates?

Ogg is inherently VBR, but it has an ABR-like mode.  ABR *always* has worse
sound quality for a given file size than VBR, but the bit rate is a little
more consistent, which is important for streaming folks.

Unless you're planning on streaming, use VBR.

For more details, you can read my intro to vorbis, especially the section
about halfway down called "CBR? VBR? ABR?"
    http://grahammitchell.com/writings/vorbis_intro.html


-- 
Graham Mitchell - computer science teacher, Leander High School

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