# iTunes Match (how good is 256Kbps AAC?



## Skidood

Neat idea...can anyone comment as to the expected sound quality with their streaming of 256Kbps AAC? (iTunes Plus)
   
  As compared to, say, CD quality, or flac?  Thanks!


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## pmc64

It obviously won't sound as good as cd quality or flac. It'll sound decent though.


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## skamp

pmc64 said:


> It obviously won't sound as good as cd quality or flac. It'll sound decent though.




Not "obviously". I don't remember reading about anyone being able to tell the difference between AAC 256 kbps VBR and FLAC in an ABX test. It most likely will sound exactly the same.


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## Skidood

Interesting.....
   
  I listen to Sirius Satelite Radio online regularly which comes in at 128 Kbps.  It sounds pretty good for streaming radio, but without having really done a critical comparison, off the top of my head Id say it sounds like a 128K Mp3 file.
  So at 256, it probably sounds decent.  Which makes iTunes Match an attractive proposition if you have a big library of lossy Mp3s in your iTunes library, as they will stream you back the same songs you already have, but in 256K quality.  28 bucks a year.  Hmm.


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## skamp

Mind that iTunes Match seems to have a rather annoying limitation right now: "explicit" versions of songs seem to be replaced with "clean" versions, I don't know if Apple has managed to work around it yet.


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## mrspeakers

FLAC is lossless compression, so it sounds to most people exactly like the original.  256K is lossy and does not provide an exact replica.  The A CD is by definition the most common source for uncompressed music, and FLAC off CD is very good.  FLAC can also support hi def audio like 24/96.
   
  256 sounds good, but there is a clear difference between it and FLAC off of a good source.  I usually rip my CDs in ALAC, which is Apple's lossless, then compress to 256 (new feature in iTunes to downsample to 256 instead of just 128) to jam more tunes onto my iPod for the gym or for travel.
   
  EDIT: 256 usually sounds flatter in soundstage and dynamics.  It doesn't offend (except sometimes mass strings), but it doesn't engage as well either...


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## GloryUprising

This is an old link, but one of my favorites to refer people to when asking about computer based compression formats:
   
http://www.stereophile.com/features/308mp3cd


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## skamp

That article is highly misleading. You don't listen to a perceptual codec by looking at graphs. The differences are in the vast majority of cases not audible. Aside from maybe some very specific "killer" samples, AAC ~256 kbps VBR will be _transparent_, i.e. audibly undistinguishable from the CD.

The whole point of a perceptual codec is to fool your ears, not your eyes.


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## GloryUprising

Quote: 





skamp said:


> That article is highly misleading. You don't listen to a perceptual codec by looking at graphs. The differences are in the vast majority of cases not audible. Aside from maybe some very specific "killer" samples, AAC ~256 kbps VBR will be _transparent_, i.e. audibly undistinguishable from the CD.
> The whole point of a perceptual codec is to fool your ears, not your eyes.


 


   
  I don't think the point of the article is to state that numerical objective measurements is representative of a listener's subjective experience; that conversation would be way to involved and not appropriate for this thread/forum section.  I think as educated consumers (which I think most people who post on these forums are) we can read this information and come to our own conclusions without being swayed to much by the results presented to us.
   
 [size=small] The take away that I got from it, is that given identical bit rates, AAC is a 'better' codec then MP3 is in terms of  what the designers of the codec decided was important information to keep and what was OK to discard (better in that it retains more sonicly 'pertinent' information).  As with all compression algorithms there is a give and take in the attempt to balance file size with transparency of the encoding and despite the give and take, I think both mp3 and AAC both offer good-excellent transparency for the file size (esp in a streaming and/or low storage capacity setting which is the situation the OP was talking about).[/size]


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## Skidood

Quote: 





gloryuprising said:


> I don't think the point of the article is to state that numerical objective measurements is representative of a listener's subjective experience; that conversation would be way to involved and not appropriate for this thread/forum section.  I think as educated consumers (which I think most people who post on these forums are) we can read this information and come to our own conclusions without being swayed to much by the results presented to us.
> 
> [size=small] The take away that I got from it, is that given identical bit rates, AAC is a 'better' codec then MP3 is in terms of  what the designers of the codec decided was important information to keep and what was OK to discard (better in that it retains more sonicly 'pertinent' information).  As with all compression algorithms there is a give and take in the attempt to balance file size with transparency of the encoding and despite the give and take, I think both mp3 and AAC both offer good-excellent transparency for the file size (esp in a streaming and/or low storage capacity setting which is the situation the OP was talking about).[/size]


 


  Well put.   I also agree with skamp. Allow me to keep the idea of my original post in perspective.  If I want top quality for home listening, I'll buy the CD and rip hi-res files to my laptop and use my DAC. My old MP3s are more for background listening, I dont care enough about 1/2 of them to even condider purchasing hi-res versons of them.


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## DaBomb77766

Quote: 





skidood said:


> Interesting.....
> 
> I listen to Sirius Satelite Radio online regularly which comes in at 128 Kbps.  It sounds pretty good for streaming radio, but without having really done a critical comparison, off the top of my head Id say it sounds like a 128K Mp3 file.
> So at 256, it probably sounds decent.  Which makes iTunes Match an attractive proposition if you have a big library of lossy Mp3s in your iTunes library, as they will stream you back the same songs you already have, but in 256K quality.  28 bucks a year.  Hmm.


 


  Isn't satellite radio 64kbps AAC-HE...?


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## Skidood

I can't recall where I saw that it is streamed at 128 Kbps.  Keep in mind this was for online listening, not actually using a satelitte radio.
  My guess is that what I actually read was implying that  (even though I recall it being really vague)  the source file quality at Sirius  is 128 Kbps, but it is streamed at whatever rate is needed.
  I fired it up and after waiting for several minutes to allow for buffering, I measured the data rate coming into my laptop using the properties screen of my wireless connection and a stopwatch.  It was 16.7 Kbps.  Hmm.


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## DaBomb77766

Quote: 





skidood said:


> I can't recall where I saw that it is streamed at 128 Kbps.  Keep in mind this was for online listening, not actually using a satelitte radio.
> My guess is that what I actually read was implying that  (even though I recall it being really vague)  the source file quality at Sirius  is 128 Kbps, but it is streamed at whatever rate is needed.
> I fired it up and after waiting for several minutes to allow for buffering, I measured the data rate coming into my laptop using the properties screen of my wireless connection and a stopwatch.  It was 16.7 Kbps.  Hmm.


 


  You sure that wasn't measured in KBps?  16KBps is 128Kbps.
   
  But I think the actual satellite data streams are 64Kbps, the bandwidth is extremely limited and it has to be shared among the many different channels.


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## Skidood

Aaahh...nice catch.....it was actually 16,667 bytes per second.  Using 1024 to divide makes it 16.28 KBps.
   
  What can I take from this info relating to quality of the files being streamed?  I guess it would depend on which compression format they use....
   
  The sound is definitely better listening online vs. using the satelite radio.


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## bowei006

if the 256kbps AAC VBR or CBR whatever they do was ripped from a CD or made from the original lossless file(99.9% what has to be done) then..most can't tell the difference. Most head-fier's cant tell the difference between anything 256kbps+ be it AAC or MP3 and lossless. ABX with foobar will give you a definite answer, i got a 1.1% at the end after an hour of siting there and doing an ABX so i guess i can hear the difference but believe me...even if i got that score. i would still not mind listening to 256kbps...it's so hard to tell. the difference wasn't big. heck one from the other didn't sound bad. they both sounded good, it's just that the 256kbps sounded a bit "different" but not bad from the lossless rip.


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## DaBomb77766

Quote: 





skidood said:


> Aaahh...nice catch.....it was actually 16,667 bytes per second.  Using 1024 to divide makes it 16.28 KBps.
> 
> What can I take from this info relating to quality of the files being streamed?  I guess it would depend on which compression format they use....
> 
> The sound is definitely better listening online vs. using the satelite radio.


 


  Well with XM satellite radio I can hear a ton of compression artifacts even in my dad's Bose car stereo, I shudder to think of what it'd sound like with a nice pair of headphones or a nice speaker monitor setup...Bose setups tend to gloss over detail like that, so being able to hear it so clearly would mean it's pretty bad.
   
  I haven't listened to any XM online radio streams though...but 64kbps is right at the edge of what is even remotely acceptable, doubling that to 128kbps actually would make a huge difference.
   
  But keep in mind they're using AAC-HE, not just normal AAC so it will sound better than any other format encoded at 128Kbps.


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## bowei006

oh in case some people didn't know the kbps is the combined bit rate. So if your song had two channels(stereo) and was 128kbps it was 64kbps per channel. 320kbps is actually 160kbps per ear. This is a new audiophile thread so i thought i'd just point that out so that your math won't get messed up or anything.


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## GloryUprising

Quote: 





dabomb77766 said:


> Well with XM satellite radio I can hear a ton of compression artifacts even in my *dad's Bose car stereo,*


 

  I stopped reading there. lol, jk. =)


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## bixby

Quote: 





skamp said:


> That article is highly misleading. You don't listen to a perceptual codec by looking at graphs. The differences are in the vast majority of cases not audible. Aside from maybe some very specific "killer" samples, AAC ~256 kbps VBR will be _transparent_, i.e. audibly undistinguishable from the CD.
> The whole point of a perceptual codec is to fool your ears, not your eyes.


 


  Maybe to your ears, but I went through this whole exercise of comparing lossy vs lossless years ago and found to my ears anything not lossless was indeed audibly different and not preferred.  While you may find a lot of folks that agree with you, there are a lot that do not.  
   
  cheers
   
  EDIT- And agree Satellite radio bl..s


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## bowei006

Quote: 





bixby said:


> Maybe to your ears, but I went through this whole exercise of comparing lossy vs lossless years ago and found to my ears anything not lossless was indeed audibly different and not preferred.  While you may find a lot of folks that agree with you, there are a lot that do not.
> 
> cheers
> 
> EDIT- And agree Satellite radio bl..s


 
  ^ I would suggest a blind foobar ABX right now in this day and age.


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## skamp

bixby said:


> Maybe to your ears, but I went through this whole exercise of comparing lossy vs lossless years ago and found to my ears anything not lossless was indeed audibly different and not preferred.




Were the comparisons sighted?


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## bowei006

Quote: 





skamp said:


> Were the comparisons sighted?


 


  sighted? what's that?
   
   
  i still call for a present day blind foobar ABX with at least 16 results. and two trials, one where he uses tracks and a song he chose. and one where we do.
   
  Tracks must be CD ripped with EAX to ensure validity into a .wav format. of which must be correctly encoded from that original wav into two files. one lossy file size and format of choosing. i say MP3 320kbps CBR and one that is Apple Lossless Audio Codec or Free Lossless Audio Codec.  This must also be done correctly. of which the files are inputed into foobar with the ABX add on and ABX'd with results being hidden. and then after 16+ tries, the test stopped and posted.
   
  anybody is free to try this. most can't hear the difference, even worse the older you are. We are not in sound Science where most tests go, but these tests will show most people if they can or can not hear and thus make them more comfortable in using correctly self ripped or itunes bought 256kbps AAC and above tracks. (i haven't boughten off Amazon so i can't compare their tracks) illegal downloaded 320kbps do not sound the same as self ripped one's BTW.(most don't)


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## skamp

bowei006 said:


> sighted? what's that?




As in, not double blind, as in, he could see what he was comparing.




bowei006 said:


> i still call for a present day blind foobar ABX with at least 16 results. and two trials, one where he uses tracks and a song he chose. and one where we do.
> 
> Tracks must be CD ripped with EAX to ensure validity into a .wav format. of which must be correctly encoded from that original wav into two files. one lossy file size and format of choosing. i say MP3 320kbps CBR and one that is Apple Lossless Audio Codec or Free Lossless Audio Codec.




You mean EAC. Doesn't really matter.

I'd go for iTunes Plus (AAC ~256kbps VBR) since that's what we're talking about here.


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## skamp

bixby said:


> While you may find a lot of folks that agree with you, there are a lot that do not.




Those who agree with me usually submitted to ABX tests (or read the results of others), while those who disagree didn't (which I assume is your case).


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## bowei006

I use itunes to rip bc like you say, very rarely will something happen and itunes has verification. Its just that to make absolutley sure i just say that


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## Skidood

Quote: 





gloryuprising said:


> I stopped reading there. lol, jk. =)


 


  Agreed, sat radio sound quality is pretty horrific, and sometimes you really hear it ( especially during one point in Deep Purple's Woman From Tokyo..I cringe everytime I hear it).  It actually seems like some audio frequencies and/or harmonics in the source material make the artifacts multiply during short periods.
  Their online streaming is noticeably better.  But I do like the product (almost zero commercials, lots of variety)  I HATE commercials.


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## DaBomb77766

Quote: 





bowei006 said:


> oh in case some people didn't know the kbps is the combined bit rate. So if your song had two channels(stereo) and was 128kbps it was 64kbps per channel. 320kbps is actually 160kbps per ear. This is a new audiophile thread so i thought i'd just point that out so that your math won't get messed up or anything.


 


  Well that's not entirely true, all modern codecs use "joint stereo" which combines some parts of both channels that are exactly the same.  So in reality a bit more bandwidth is dedicated to each channel.


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## groovyd

Just curious are the Matched AAC files iTunes delivers for their matching service encoded from CD or from studio masters (which are much higher fidelity then CD) ?  
   
  I guess I am wondering if even at 256kbps AAC they may be of better sound quality then the CD straight ?
   
  Is there any online reference that discusses the process Apple uses to create their music files from the studios?


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## Erukian

While iTunes does sell 24bit audio (anything that's Mastered for iTunes) iTunes Match will not give it to you.
   
  Here's a comment from another forum
   
   
   


> [size=13.63636302947998px]I tried it with one track, and they did not match with the Mastered for iTunes version. [/size][size=13.63636302947998px][/size]
> [size=13.63636302947998px]
> [size=10pt] I ripped in a track from a Diana Krall CD.[/size]
> [size=10pt] I uploaded and it matched on another of my machines.[/size]
> ...


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## otaku313

Just as a rebuttal to those who say that only a "Golden Ear" can tell 256K AAC from Lossless, I want to say that I am an old man who definitely does not have golden ears, but I can hear the difference under ideal conditions:
   
  1. A well-recorded song that I am very familiar with ("So What" from Ministry)
  2. A long sample (at least a minute)
  3. An excellent playback system (Macbook Pro, AudioQuest Dragonfly, AKG K701's)
  4. A quiet room
  5. The volume turned up loud enough to leave my ears ringing.
  6. Lots of practice.
   
  Under these conditions, using the ABXTest software, I can distinguish AAC from Lossless 60 to 80% of the time.
  Definitely extreme conditions, and definitely not a perfect performance.
  If I change these conditions (shorter sample, lesser headphones, lower volume, unfamiliar piece of music) I cannot tell the difference at all.
  But when the conditions are perfect, the difference is audible to me.
   
  Otaku


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## groovyd

i'm especially curious about the new Rush 'remastered for itunes' set and does it have higher bit rate or precision then my 16/44 cd rips?  I would love to get that set if the sound is better but not if it is the same.


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## hogger129

I find that 256 AAC is so close to CD quality that it doesn't pay to buy the CD unless it costs less.


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## rjohn

groovyd said:


> i'm especially curious about the new Rush 'remastered for itunes' set and does it have higher bit rate or precision then my 16/44 cd rips?  I would love to get that set if the sound is better but not if it is the same.


 
  
 It's 256 but it's supposedly mastered better and it probably sounds better.


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## dizzyorange

Yeah people who say there's a big difference seriously need to do ABX.  In most case where people can tell the difference, it as an above poster put it, in absolutely perfect conditions with a track you're very familiar with, and even then you'll still guess wrong some of the time.
  
 I used to be one of those "of course there's a difference" people... until I did ABX, and found I had to repeat very specific portions of songs over and over again to tell the difference, and even then I would be wrong about 20% of the time.  
  
 The funny thing is when I do the test in a non-blind fashion, the FLAC sounds better in every way.  There seems to be better spatial definition, more ambiance, better highs, tighter bass.  But as soon as you blind yourself to which is which, it's amazing how those differences almost all disappear.  
  
 It's also quite sad when you hear people say "FLAC is almost as good as CD." when they are exactly the same thing.  These are the same people who believe putting CDs in the freezer makes them sound better.  
  
 The human mind is easy to trick.
  
 You have to do a blind ABX test, or otherwise you're deluding yourself.
  
 Of course, I'm talking about well-encoded lossy formats.  Apple's 256 AAC is certainly well-encoded.  LAME 320 and v0 (or even v3) is also excellent.
  
 If you're downloading 320 files from random places on the web (like mp3skull), be aware lots of those files aren't encoded from proper lossless sources.  It's easy to rip a song from youtube and encode it 320.  Of course in that case it's not gonna sound so good.


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## hogger129

dizzyorange said:


> Yeah people who say there's a big difference seriously need to do ABX.  In most case where people can tell the difference, it as an above poster put it, in absolutely perfect conditions with a track you're very familiar with, and even then you'll still guess wrong some of the time.
> 
> I used to be one of those "of course there's a difference" people... until I did ABX, and found I had to repeat very specific portions of songs over and over again to tell the difference, and even then I would be wrong about 20% of the time.
> 
> ...


 
  
  
  
 When people say "FLAC is almost as good as CD," I would seriously question what they're using for playback, or if they used a secure ripper like EAC or dbPa.  CD ==> FLAC = CD.  I _have _heard some people say that playback is not perfect, and that FLAC should only be used for storage purposes, but I think it's a load of BS unless you're on a really old computer whose memory and processing power are not up to task.
  
 256 AAC is pretty dang good.  I have some fantastic examples that I have purchased through iTunes in the past when I just wanted a couple odd and end songs.  I prefer lossless more for theoretical reasons than anything.  And if I like the entire album, whatever I'll go spend $12 and get the CD.
  
 I would amend my previous statement also to say that CD is also worth buying if you want the physical product (like if you are a collector) or it's a better mastering, etc.  Because I'll go out to the used bookstore that sells used CD's and I'll get old ones from the 80s and 90s because newer ones are victims of the Loudness Wars.


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## MattiaFalsetti

FLAC is the best, however the 256Kbps AAC sounds well.


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## cdvsmp3

pmc64 said:


> It obviously won't sound as good as cd quality or flac. It'll sound decent though.


 
 I would not be so sure about it... Try this blind test: http://cdvsmp3.wordpress.com.


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## lextek

I've been enjoying iTunes Match since it came out. Always thought it sound good. It's to easy to buy music from iTunes. That almost instant gratification. I have been buying more CDs(used/cheap) lately. NAD a crazy notion of buying a turntable again. Thing I'll just get a Mac Mini......


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