I hear a lot about CBR and VBR; what’s wrong with ABR?, Was “MP3 ABR WHY NOT.” (shouting won’t make anyone likelier to reply) Options

[soylentgreen]

I have read numerous forums and articles about mp3 cbr and vbr, some swear by cbr others vbr, the debate just goes on and on. I,ve tried cbr 256, vbr 256, cbr 320, cbr 192 cbr etc and I cant hear any difference. My question is why bother with cbr or vbr, why dont people just go with MP3 ABR, would this not be the ideal compromise, or I am missing something, as there does seem to be lack of mp3 abr on offer as downloads from the likes of Napster etc.

[halb27]

In the roughly 120-240 kbps bitrate range, probably VBR is the best way to go, as far as no serious VBR weakness of the encoder used is known and no special considerations (like streaming) have to be taken into account. Not having serious weaknesses as does Lame 3.98.4 IMO means the psy model is quite alright, and you get an efficiently encoded mp3 file. This applies to Lame 3.98.4 -V5 to -V0.

When going higher in bitrate you don't have a choice for VBR as long as you go with standard Lame, and the only CBR choices are 256 and 320 kbps here. It's a pretty large gap between the two choices. 256 kbps isn't very attractive because it can hardly be expected to give a seriously better quality than -V0. For ABR this huge gap doesn't exist, and you can go with any average bitrate according to your likings.

ABR shouldn't be seen too much IMO in the face of 'roughly predictable bitrate', because nobody really needs this. Either you need a constant bitrate like for streaming, or you can use a variable bitrate as nearly anybody does, and in this case you can use a full-fledged VBR mechanism.

ABR has its merits in the 256-320 range because of the large CBR gap mentioned. ABR (like CBR) is useful also if you have reason not to totally trust in the VBR audio creation process which totally relies on the psy model.
The audio data creation process of CBR and ABR is basically the same, with a higher amount of audio data rate variability on the ABR side, and letting the user gaplessly choose his bitrate demands.

This post has been edited by halb27: Oct 7 2011, 14:26