[MPlayer-users] abr audio

[Arpi]

Hi,

> 
> how does actually abr-audio encoding work?
> 
> what i don't understand is this:
> 
> it's done in 1 pass... then how can mp3lame know how many bits can he
> use for the audio ? i mean abr means at the end the audio will be
> average x kb/s.... that means sometimes above, sometimes below...
> 
> how does he know how much can he go above / below if he does this in 1
> pass?

it's a short-time vbr with buffering.
same as 1pass of video but video is always vbr, compressed frame sizes
differ. mp3 cbr means very constant compression ratio, ie the 32*36 pcm
samples are compressed to N bytes where N is constant in cbr mode.
in ab rmode it allows farme size !=N but it trie sto reach teh wanted
bitrate so it won't allow too many big frames etc


A'rpi / Astral & ESP-team

--
Developer of MPlayer, the Movie Player for Linux - http://www.MPlayerHQ.hu