MP3 Confusion, thought I undertstood this...

I just read something that said that VBR is "better quality" than CBR in all instances except 320kbps. Even when matched in kbps, such that a 128 VBR MP3 is argued to be better than a 128 CBR MP3. I'm completely confused.
I thought this was all a matter of bitrate. How can one say for example that 190 V2 VBR is better than 256 CBR by virtue of nothing more than being VBR? That seems bass-ackwards to me.

Please stop the brain-fry happening in my head and help me understand this.

 

P.S. I do know how to spell "understood". But I have no way of editing the title for some reason.

 

Sounds more appropriate misspelled. My fix, avoid all MP3's and problem solved, I don't have to understand it.

 

Yeah, unfortunately I've got this weird thing about wanting to learn about things I don't know about.

 

I don't think anyone claims this. VBR is better than CBR at a comparable bitrate, not any bitrate.

 

So at the same bitrate a format that trims out unneeded frequencies is better quality than one that doesn't? I can see it being more efficient and smaller, but better quality isn't something I understand.

 

A 128 VBR is better than a 128 CBR because there are brief instances during the music where the 128 VBR can allocate more bitrate when the music needs it. For example, during every cymbal hit the VBR bitrate can increase above 128, while with the 128 CBR the bitrate has to stay exactly the same all the time (even during moments in the music when there is not much going on).

Making the argument that 190 VBR is better than 256 CBR is more difficult. I'd be a bit confused by such a statement as well unless backed up by some good explanations about how they came to that conclusion.

 

The idea of, for instance, a 256 VBR compressed file is that it averages at 256kB/s. During complex passages, it will go over 256 - and conversely, it will compress harder during simple passages. This gives it a sonic advantage over a fixed bitrate of the same value.

edit: I see Ham Sandwich beat me to the punch. Well put, HS!

 

It doesn't "trim out unneeded frequencies". Or, more precisely, all mp3 does that, but that's another discussion. The difference between VBR and CBR is that VBR can use a higher bitrate where it's really needed and lower where it's not needed. You don't get better quality with CBR, because VBR already uses that high bitrate everywhere it needs it.

 

Ok, I went back to what I saw. It was a site that argued, in badly expressed language, that VBR is preferable even when the bitrate is higher. So, this was pointless. Thanks for helping me understand. Obviously, your explanations make sense. So in order you'd say... VBR 256, VBR 192 are THEN CBR 192?

 

In order of quality it is safe to say VBR 256, VBR 192, then CBR 192.
It gets more confusing if wanting to rank something like VBR 192 against CBR 256

 

Ok, great. I won't ask what the point of ABR is then, I'll look that up some other time.

 

Here's LAME's explanation of ABR
from http://wiki.hydrogenaudio.org/index.php?title=LAME

 

So, a VBR that you can aim more accurately at a certain bitrate and therefore file size while still allowing for the encoder to focus bits where necessary. So a more precise and fine tuned version of VBR. ...I guess?

 

I'd call ABR a more restricted and compromised version of VBR.
I'm not sure where ABR would be needed. Maybe as part of a video codec where you might need a predictable block size of audio data between every frame in order to make it easier to keep the audio and video in sync? I don't see ABR being useful as a straight audio only option. Better to use VBR if your interest is to maximize audio quality for the space used.

 

No, the most fine-tuned and precise modes are the LAME encoder presets (-Vx):

http://wiki.hydrogenaudio.org/index.php?title=LAME#Recommended_settings_details

 

I'm not either.

Then again, I still don't get the true difference between ABR and VBR. I mean, VBR IS an average. So, thanks to tinpanalley, I'm also a bit confused.

If you have a file at 256 VBR, that's supposed to mean that 256 is the average, correct? In other words, it can go as high as 320, or as low as 192, as needed.

So, if it's 256 ABR, what does that actually mean? Shouldn't it be the same thing?

 

http://wiki.hydrogenaudio.org/index.php?title=Average_Bitrate

 

I'll admit I'm a complete dunce.

That link and explanation still doesn't clear up anything for me.

Can you summarize?

"General benefits of VBR"? "Relatively predictable file size"?

Ummmm...

 

VBR: The number of bits per frame used is determined by the quality setting of the encoder
CBR: Will use the same number of bits for each frame based on the target bit rate setting
ABR: Sort of like a cross between the two. Will tend to use more bits per frame (depending on the target bit rate).

 

I'm honestly trying to work with you here, brother.

But...*



*not that I'm calling you "cute". Well, you might be, but that isn't for me to determine...

 

I really appreciate all the help guys, but the difference between VBR and ABR is a big mystery to me. And I know, I know, this doesn't matter so who cares? Well, I care cause I like to know about this crap and if the community here isn't the group to talk to about it then who is? I can tell you this is not something that would go over well over dinner with friends.

 

+1,000,000,000,000!

 

Say you need your filesize to be 5 Mb. You can then use ABR to vary the bitrate in order to make an mp3 of exactly 5 Mb. This is for specialised use, like audio dubbing for games.

 

Wait a minute. So it's strictly about file size?

OK, that makes sense.