[vorbis] ABR or CBR?

Segher Boessenkool segher at chello.nl
Sat Jul 7 14:13:48 PDT 2001



Monty wrote:
> 
> > Forget about what I quoted before.  Probably, by CBR, Monty meant ABR
> > since CBR is stupidly patented and this is the reason why Vorbis has
> > no CBR option.
> 
> Incorrect.  CBR is not patented and Vorbis has no CBR option because
> it is not natively CBR.  MP3 is based on fixed sized frames, Vorbis
> is not. (MP3 actually implements a limited ABR on top of the fixed
> size frame option, so CBR is a misnomer for MP3 as well).
> 
> By 'CBR' I mean 'simulated fixed bitrate within a small window of frames', the
> same thing it means in MP3 (where the window is nine frames).

No, it's not 9 frames, it's 4095 octets.  Maximum backward frames
needed is nine frames, yes.

Cheers,

Segher

(Sorry, being anal again)

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