Variable Bit Rate: Getting the Best Bang for Your Byte

you should normalize to 98% or even 96% volume level, that should really help any clipping…

as for ‘slipping’ if you really mean that, the music is sliding? or something like that, i have no idea, the latest lame 3.97 encoder does not screw up like that for me

(although slipping at high volume does not make sense :wink: playing something loud should not introduce artifacts like a slip… so i’d bet he said clip)

I just read through all the post and learned quite a bit. My ending question, however, is that with hard drives so large and cheap, why would I not want to record in MP3 at 320 Kbps, maybe with Windows Media Player?

I have about 800 CDs and if I’ve done the math correctly, at about 50 minutes each this would only take up 89.47 GB at 320 Kbps, which is only about 44 GB more than if I’d record all of them at 192 Kbps.

Am I overlooking something here, or is my math wrong? Also, wouldn’t MP3s at 320 Kbps be considered pretty much CD quality, and plenty acceptable for general listening?

Thanks for any comments
eobler@bellsouth.net

I’m on a Mac…

Since you’re on a Mac, you most likely should be able to do a batch conversion from the command line… There should be something like faad/faac available for MacOSX which would allow you to do a batch conversion of your files using a bit of shell scripting the flac command with the -d flag and piping the output to faad for the encode… similar to:

for i in find /your/path/ -iname '*flac';do flac -d “$i”|faac your_options -o /path/to/"$i".aac;done cd /path/to/*aac rename flac “” *

You need only one line, leave the computer crunch the files and return to see your files. The third command (don’t know if it is available under MacOS, but I would surprised if it wouldn’t) should strip your converted files from the suffx “flac” before the aac extension, leaving you with clean .aac files.

“Also, I think there’s something inherently wrong about MP3 VBR. Why does the encoder limit itself to multiples of 32 kbit? I haven’t seen the Vorbis encoder do that.”

That is due to the mp3 format, the bitrate is set by 4 bits in the 30 bits long frame header (of which 11 are indicator bits). 0000 = bitrate free, 1111 = bitrate reserved. then depending on layer the bitrate can be deduced from a lookup table. For the usual mp3 format (which is, i think:mpeg 1 layer 3) the table looks like this:32,40,48,56,64,80,96,112,128,160,192,224,256,320.

What an interesting blog with a lot of illumination;
While this started as the most bang for the byte, i guess eventually one gravitates towards least lossless for the byte.

I realize I can rip to any lossless codec [choose your fav - http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison]. Hopefully the different codecs are interchangeable. Besides I could change to lossy formats depending on the player.

The CD would still remain the ‘archival copy’ for me. I dont have to deal with the DRM nonsense.

Wow, it was well worth the time reading this blog. Thanks to everyone who contributed. What I’m wondering is how to convert existing MP3 audio files that I have @128 bitrate to a 320 bitrate. Is there some converter out there that will do the job?

John: You cannot increase the quality of mp3s by converting from 128 to 320. You need to rerip from the original source or a lossless file like flac to 320 in order to gain that quality.

Thank You for the info Josh

Is there a downside to converting from high-quality mp3s (say, 320 kbps CBR) to lower-quality VBR as opposed to converting directly from CD? When I go CBR-VBR in WinLAME, it gives a warning about converting from “one lossy format to another”, but the result sounds fine to me.

Thanks folks . . . . . I am off to buy a few more Audio CDs and Audio DVDs and I’ll keep them that way . . . No ripping for me . . . .

Here’s why I don’t use Ogg: there are hardly any portable/car players which support it (or there were last I shopped ~1yr ago). Otherwise, yes it’s great.

Last I checked, there is. The iPod, believe it or not. Ok sorry, buy the iPod than put firmware on it. (ok i kno that post is old but yes!) The open-source RockBox will give your iPod the ability to play Ogg!

OK, here’s a question… I have about 600 CD’s - originally burned from mostly 128kbps MP3s (along time ago). I’ve now added them to my iTunes library, and after I was done, I noticed that I had set the default setting for importing files to MP3 @ 192kbps… now, the do take up a bit more space than the original 128kbps files, and I know that there’s no improvement in sound quality - but what I am more worried about: Has the quality decreased? If yes, I would need to reimport all 600 CDs… and: How can I figure out whether the .cda files were originally 128 kbps or 192 kpbs???

Dear Jeff,
Great blog with useful info. I am interested in making archival copies of brain entrainment discs I own (HemiSync, HoloSync, etc.) Have you any suggestions for the best method to do this, insuring the integrity of the encoded binaural beats? Is either WMA lossless or a WAV format any better than the other? Since this encoding is sometimes hidden in white noise would a fixed rate be better than a variable rate?
Thanks,
Dennis

VBR is fantastic for standalone audio. Using it with video is another story…

i’ve found that it makes a difference in where you listen to your music from, while my laptop is being repaired i’m using a this laptop where the only thing thats better is the processor, the speakers are right next to eachother, but whats even better on my laptop is it has HD sound, i don’t know weather i should convert my music to mp3 or keep it wma, my bullet for my valentine CD is mp3 with 320kbps, while others are wma at only 128kbps, i dunno weather i should, i would like some info, so Email me at jamboy1@hotmail.co.uk

I am finding out that some iPods-- even the latest and greatest models-- have problems with VBR files. They can’t seek properly, don’t resume right, etcetera.

This may be the fix:

http://txfx.net/2005/02/08/vbr-mp3-fix/
http://www.willwap.co.uk/Programs/vbrfix.php

the bit rates and the formats I use is 224kbps mp3 CBR and 255 - 355 WMA VBR. Any lower on any of these formats has too many artifacts.

Here is my take. At 128, which is what most songs I have were or are, on my iphone they suck. The level of audio is crap. I have been using 192 or higher and the quality as well as the volume are far far superior to 128. I also use vbr as it seems to have a better sound. What I can’t figure out, is why some songs that were 128 that I changed to a higher bit rate sound no different. I have used several devices as well as different headphones and no noticable difference at all. Not sure. Most do, some don’t.

What I can’t figure out, is why some songs that were 128 that I changed to a higher bit rate sound no different

You can’t simply reencode the same file at a higher rate because the information above 128kbps so to speak has already been stripped from the file. If you were to reencode the 128kbps file at 192kbps, you’re just filling it with redundant information. You need to go back to the original source (probably CD) and reencode it at the higher bitrate.

With statements like this, I happened to pick the outlying song on this particular CD …

{outlying song??? what the hell are you talking about?}

and this, There’s something magical about that extra 32 kbps; the difference between a CBR MP3 at 128 kbps and 160 kbps has always been unusually large to my ear.

It sounds like you’ve been spending WAY too much time hanging out with all the other fruit loops over at hydrogenaudio.