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Music ripped from CD with iTunes vs Music purchased on iTunes (Quality) - Page 2

post #16 of 22
Quote:
Originally Posted by bikefixe View Post

I assumed, perhaps incorrectly, that VBR = variable bit rate, and that if you rip at 256 VBR, 256 is the max bitrate, and for sections of lower complexity in the music, the actual bitrate will be lower than that max. Anyone care to confirm or educate me?

I'm pretty sure that the average bitrate is supposed to be around 256kbps but I could be wrong. If there are a lot of empty passages or something it's going to be a lot lower.

 

It's probably around as good as 320CBR(constant bitrate), not better. It wouldn't make a whole lot of sense for it to be better if it's doing the same thing as a 320CBR at the most complex passages. I'm curious if the lowpass filter is lower than a 320CBR(in mp3), I'll have to check on that.


Edited by chewy4 - 4/12/13 at 5:08am
post #17 of 22
Thread Starter 
Quote:
Originally Posted by bikefixe View Post

I assumed, perhaps incorrectly, that VBR = variable bit rate, and that if you rip at 256 VBR, 256 is the max bitrate, and for sections of lower complexity in the music, the actual bitrate will be lower than that max. Anyone care to confirm or educate me?

 

Very simple,  VBR is variable bit rate so you can never expect or predict its actual bitrate before ripping. Imagine an audio file is made up from very small audio chunks called frames, each frame would have it own bitrate when recorded, when chosen to encode with VBR, the encoder knows that it has to choose which bitrate is best to use with each frame according to the required value of data (lower value will be applied if there's not much audio going on and boost it up when needed), hence the final bitrate is unpredictable. That said, saying 256 VBR is maxed at 256 is somewhat contradicting, only because with a real mechanism of VBR encoding, as in dbPoweramp, you can't choose the the desired bitrate to rip with, but will rather see settings like -V0 or V0.5....which indicates how high the outcome quality will be, and is rounded as close to 240kbps VBR (as good as 320kbps CBR) for MP3 but not always close.

 

Some says iTunes VBR might use a different method to encode, in fact we doubt that they use ABR (similar to VBR but with more predictable bitrate) for audio encoding. I've tested some of the songs ripped from my CD and lossless format to AAC with this VBR setting on, 4 out of 5 I couldn't guess the average or constant bitrate of the song after ripping. So saying they're using ABR still a vague theory, yet the ripped quality is exceptionally good so I don't care that much. 

 

Long story short, I think Apple do have a point on navigating people to trust in their music store, for most is still better than 320kbps MP3 if you're not comparing them directly to CD or Vinyl, which is good enough for most digital audio player and end consumer. I used to think 320kbps MP3 is superior but after researching and learning myself, now my music library is alll AAC and ALAC/FLAC at least I'm ensured that my audio quality is not cut off at the very limit of 20kHz as in MP3..the rest is down to your personal choice and what you think is best for your quality demand :D

post #18 of 22
Thread Starter 
Quote:
Originally Posted by chewy4 View Post

Yeah it's hard to say which is better, but I just used nero for testing since that's what you can use with dbpoweramp.

 

They must be using different parameters than you. That might mean that it's technically better, but it could also mean the opposite. Remember that those high frequencies aren't even audible for most adults, especially not amongst other sounds in music, so IMO it's a good idea to throw them out with lossy compression. 

 

Your file does look like it cuts off more than a 320kbps AAC file should though, it looks closer to 256kbps.

 

I have it all figured out the other day, my brother ripped this song and when I bombarded him with questions, he admitted that he ripped the CD to AIFF with iTunes, then ripped this AIFF to AAC with another third party encoding software which I've never heard of. That explains why the spec is much lower than those when ripped with iTunes. 

 

Thanks for looking into my concern anyway :) 

post #19 of 22

There is an interesting thing you could do to compare a song bought from iTunes and the same song ripped and converted to iTunes plus using iTunes application.

You'll need an audio editor like Adobe Audition, for example:

Load the original (purchased) track and the ripped track.

Invert one of the tracks (inverts, i.e. changes the wave phase 180 degrees) Make sure you align the tracks perfectly before you mix them.

Mix the tracks in a multitrack session and listen to the result. If the tracks were identical, you should get absolute silence.

This video helps with the mixing process: https://www.youtube.com/watch?v=UoBPNTAFZMo&list=PLwoW0oKPqI56AF7NkF0lxBA1ubtO1nBND

 

___________________

cdvsmp3.wordpress.com

post #20 of 22
Quote:
Originally Posted by bikefixe View Post
 

I assumed, perhaps incorrectly, that VBR = variable bit rate, and that if you rip at 256 VBR, 256 is the max bitrate, and for sections of lower complexity in the music, the actual bitrate will be lower than that max. Anyone care to confirm or educate me?

 

The overall average will be 256, but there may be complex sections where it goes up to 320. VBR will allow the bitrate to go above the rate you have it set for. There really is not reason not to use VBR on bitrates below 320. It can't go above 320 though, so if you do 320 VBR, the 320 will be a cap like you say.

post #21 of 22

When I rip/re-encode to a VBR format, I always use two pass encoding. It takes a little longer, but is worth it.

post #22 of 22

iTunes doesn't have two pass encoding, but it has safe ripping for scratched disks. I use that all the time.

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