[BlueApple]

Even though I've set to rip at ACC 256k, without variable bit rate in the preference; after ripping a CD, I've found out that the bit rates of each songs is a little different. It used to at 256k just like I pre-set it.

What happened? It's that a new feature? A bug? Why?

[BlueApple]

Does this happen to anyone?


Thanks

[PB PM]

Only if I turn VB on.

[remlemasi]

Yes. I noticed this after I installed Leopard. I set it at 320 Kbps but it ranges from 310 to 325 Kbps.

I did a bit of research on google to find out why:

Apparently, even though VBR isn't enabled, iTunes has always encoded at some very strict form of VBR that keeps the bit rate very close to what you want. Enabling VBR just gives it more room to vary the bit rate. All that's changed is that iTunes now displays the actual bit rate of song and does not round to the nearest bit rate that you wanted.

I checked to see if this was true for older song that had been ripped pre-Leopard. While iTunes displayed the "rounded" bit rate (320 Kbps), I went to "Movie Info" in QuickTime and found that the bit rates were not exactly 320 Kbps either. I didn't look through that many songs (maybe 3 or 4), but I found some that were at 318 Kbps. I didn't find any that went as low or high as 310 or 325 Kbps, but again, I didn't look through that many. Perhaps iTunes gives more room to vary the bit rate in 7.5 (though still less than if you enable VBR).

I don't have links for this info, but I found them off of google and in some other forums. Can anybody confirm this?

[BlueApple]

Nice find! Thanks for the info.

Originally Posted by theelmerguy Yes. I noticed this after I installed Leopard. I set it at 320 Kbps but it ranges from 310 to 325 Kbps. I did a bit of research on google to find out why: Apparently, even though VBR isn't enabled, iTunes has always encoded at some very strict form of VBR that keeps the bit rate very close to what you want. Enabling VBR just gives it more room to vary the bit rate. All that's changed is that iTunes now displays the actual bit rate of song and does not round to the nearest bit rate that you wanted. I checked to see if this was true for older song that had been ripped pre-Leopard. While iTunes displayed the "rounded" bit rate (320 Kbps), I went to "Movie Info" in QuickTime and found that the bit rates were not exactly 320 Kbps either. I didn't look through that many songs (maybe 3 or 4), but I found some that were at 318 Kbps. I didn't find any that went as low or high as 310 or 325 Kbps, but again, I didn't look through that many. Perhaps iTunes gives more room to vary the bit rate in 7.5 (though still less than if you enable VBR). I don't have links for this info, but I found them off of google and in some other forums. Can anybody confirm this?

[shatteringglass]

I also ran into this "issue" when ripping a disc today. Apparently, this is occurring due to QT 7.3. This thread on Apple's discussion board explains it better: http://discussions.apple.com/thread....sageID=5879410

The AAC encoder has been upgraded in the latest QuickTime and now has more options but the iTunes interface hasn't been updated to accurately identify the options. There is now no Constant Bit Rate (CBR) so when you select 128kbps and leave the VBR box unchecked what you are actually getting is Average Bit Rate (ABR) which is why you're seeing various bit rates. iTunes doesn't currently have all the encoding options that QuickTime has. This is probably a decision to keep the interface simple but it clearly needs some tweaking so that users at least know what they're getting. The current AAC encoding options in the latest QuickTime are: CBR (now not available in iTunes) ABR (in iTunes when you leave VBR unchecked) VBR Constrained (in iTunes when you select the VBR option) VBR (this is true Variable Bit Rate but not currently available in iTunes)