[MikeD]

Is there a chart somewhere that shows the quality and size differences between the two formats? ie, is a 128kbs AAC song better than a 192 or higher kbs mp3???

[sworthy]

Sorry I'm not too helpful, but I think it's roughly half. So an AAC at 128 is like a 256 mp3. Correct me if I'm wrong.

[Commodus]

I believe the official line is closer to 192 Kbps MP3, though from people who say that they've already encoded AAC it's more like 160-192 Kbps depending on the particular track.

[chrisutley]

All I know is the AAC files sound great, at least the previews do because I can't download!!! ARGGH!

[MikeD]

so if you're getting max 192kbs mp3 quality with a 128kbps AAC file... what is the savings in physical size? Anyone know off hand? ie, if I have a 5mb 196kbps mp3 file, what is the size of the 128kbps aac file? and is this linear as you increase kbps rate?

Mike

[GORDYmac]

Where is QuickTime 6.2? I can't download it anywhere, SU, Apple's site, MacUpdate... Is there a link anywhere?

EDIT: Never mind:
http://www.apple.com/quicktime/download/standalone/

[mdc]

i ripped all my cds into iTunes at default 160kbs. i am not audiophile, i do not listen to my music on a stero, let alone an expensive pair of speakers if there are speakers hooked up to my iBook. most of the time with headphones on, and i am perfectly happy with the sound.

i downloaded quicktime 6.2 ( www.apple.com ) bottom of the page, has the little images, there is a quicktime one.

i converted one of my tracks to an AAC file ( default 128kbs ). the mp3 was 3.6mb the AAC is 2.5mb and to me it sounded the same.

my iBook is currently converting my 5.4gig collection as i type.

[klinux]

128 kbps CBR encoded music in any format (mp3, AAC, ogg, wma) will roughly be about the same size i.e. one minute = one megabyte. The difference is in how they sound at the same bitrate - which is the subject to much debate. Most agree that that the newer codecs (AAC, WMA v9, Lame MP3) sound better than the original FH MP3.

In any case, most of the debate in sound quality are in the lower bitrates used for streaming i.e 128 kbps or lower. For example, you will never find a comparison of MP3 vs OGG vs WMA at 320 kbps because in controlled listening experiments they sound virtually indistinguishable from the CD original.

[ericwass]

Does it make any sense to convert my MP3 library to AAC at a lower bitrate to save space on my iPod? Like take a 192kbps or 160kbps MP3 and re-encode it to a 128kbps AAC. Or will it sound crappy? I.E. do you have to rip AACs directly from the high-quality AIFFs to get the sound quality/bitrate advantage? Any thoughts would be appreciated.

[beverson]

Originally posted by ericwass:
Does it make any sense to convert my MP3 library to AAC at a lower bitrate to save space on my iPod? Like take a 192kbps or 160kbps MP3 and re-encode it to a 128kbps AAC. Or will it sound crappy? I.E. do you have to rip AACs directly from the high-quality AIFFs to get the sound quality/bitrate advantage? Any thoughts would be appreciated.

My understanding, which may be wrong, is that the file will sound exactly the same, unless you go lower than a bit rate of 128 on the AAC file. It won't sound any better (you can't regain quality you've already lost in compression), but it shouldn't sound any worse. I have not tried it though.

Personally, I'm torn as to whether I should re-rip my CDs or just convert my mp3s, most of which are at 192. I will at some point be moving everything to AAC, though, to save space.

[fisherKing]

why not ogg vorbis??

i think moving from mp3s is a bad idea, unless aac becomes the new mp3, ie a new standard.

too many mp3 players, files out there.

just me maybe, but i like the idea that i wont have to convert files every time a new "better way" comes along...

[pokka]

If you convert your original CDs to AAC 128kbps, it will be worth it.

If you convert your MP3s to 128kbps, then you are transcoding. And in almost all cases, transcoding is very bad for quality, because with lossy compression like MP3 and AAC, you lose quality every time you encode.

Try decompressing a 128kbps MP3 to wav and reencoding it to 128kbps mp3. It sounds horrible; you will hear strange swirling sounds when any high-frequency instrument is played. This is due to transcoding. 160 kbps is better, but you can still hear the swirling. 224 + is usually fine (as long as you don't transcode more than once).

But the transcoding artifiacts might not bother you as much as they do for me, so it wouldn't hurt to try it out on a couple of songs and see how you like it.

[jmelrose]

From what I've read, and I've done quite a bit of research, the very best bet for high quality AAC encodes is to go back to the master source, AIFF for CDs. MP3 compression removes data, so when iTunes tries to convert it to AAC it isn't working with the full picture anymore. Apparently even if you go MP3 --> AIFF (CD file format) --> AAC the sound quality is poor.

On the upside, I am in the process of re-ripping about 4K songs from my CDs to get the sound improvement with reduced size, and the nice part of iTunes is if you put the CD in and drag it to the Library, if you already have the names/labels exactly in your library as the data comes off the CDDB, it will ask to simply replace the track with the new rip, which then allows your playlists to remain untampered with. I have saved several hundred MB of space already, after about 25CDs.

Good luck.

[gostan]

So if I understand correctly, I need to re-rip my original source cd's in itunes 4 in aac format in order to have the highest quality sound because a conversion from a compressed mp3 to aac will not be equal in sound quality. Also, there is no reason to encode the music in aac higher than 128kbs because I will not be able to hear any difference. (I note that itunes 4 allows you to increase from 128kbs to 160 or 192 or even 320. I do not really understand why a higher rate will not sound better. Any feedback will be appreciated before I start re-ripping cd's.

[jmelrose]

The quality of an AAC will sound better, certainly, but beyond a certain point, proably 192bps AAC, you won't really hear a difference between it and a CD. with an MP3 the number is like 256bps or perhaps higher.

I don't remember what your MP3 are ripped at. I will tell you I just did a soundtest with my Klipsch 2.1 speaker set, and a 160bps MP3 of Barenaked Ladies' "Jane" sounded lower-quality than a 128bps AAC. The AAC had more defined bass, crisper highs, and overall improved audio clarity. In my opinion, the effort I am going to put into the re-ripping will be worth the effort.

On the service, It would have been nice if the spoken word CDs were encoded a bit lower, as the tracks can tend to be long and the sound quality isn't as crucial.

Plus, where's the Dave Matthews Band?!

[mbperk]

Originally posted by jmelrose:
Plus, where's the Dave Matthews Band?!

No your talking. I was disappointed they did not have them in there too. I sent in request to add them.

They need to put up some of their live goodies.

[gostan]

jmelrose:

Did you simply convert barenaked ladies from mp3 to aac in itunes or did you re-rip cd?? I am still curious if there is a noticeable sound difference between one or the other. I am conducting comparisons tonight. Thanks

[zigzag]

Originally posted by gostan:
So if I understand correctly, I need to re-rip my original source cd's in itunes 4 in aac format in order to have the highest quality sound because a conversion from a compressed mp3 to aac will not be equal in sound quality. Also, there is no reason to encode the music in aac higher than 128kbs because I will not be able to hear any difference. (I note that itunes 4 allows you to increase from 128kbs to 160 or 192 or even 320. I do not really understand why a higher rate will not sound better. Any feedback will be appreciated before I start re-ripping cd's.

http://www.geocities.com/altbinaries...l/mp3test.html

This link, which I got from a similar thread, demonstrates that the very best ears in the world, with the very best equipment, can't distinguish a 256-bit mp3 copy from an original CD, and can distinguish a 128-bit mp3 copy, but with some inconsistency (even prefering it in some cases).

Since AAC is considered to be significantly better than mp3, it's extremely unlikely that, under ordinary listening circumstances, you would miss anything by encoding in AAC at 128, which is probably why it's the default. My advice is to go with 128, relax and enjoy.

[jmelrose]

I re-ripped from the CD. As I said before, the MP3 to AAC encode would result in a fairly lousy sound quality.

I wonder if new CD releases will come out on the music service as promptly as they do in record stores? I'd love to have a "midnight sale" every Monday night via itunes...

[cjrivera]

Here's another...

which would have better quality?

mp3 (192kbps) burned to CD (aiff) then ripped to AAC (128 or higher)

or

mp3 (192)?

[Eug]

Originally posted by zigzag:
http://www.geocities.com/altbinaries...l/mp3test.html

This link, which I got from a similar thread, demonstrates that the very best ears in the world, with the very best equipment, can't distinguish a 256-bit mp3 copy from an original CD, and can distinguish a 128-bit mp3 copy, but with some inconsistency (even prefering it in some cases).

Since AAC is considered to be significantly better than mp3, it's extremely unlikely that, under ordinary listening circumstances, you would miss anything by encoding in AAC at 128, which is probably why it's the default. My advice is to go with 128, relax and enjoy.

I wouldn't necessarily agree.

While I haven't really tested AAC much, from what people claim, 128 AAC is probably in the 160+ MP3 range, with a few claiming up to 192 levels (depending on the encoder).

I can tell you that for myself, if I use a good system, on some tracks I can usually apart 192 MP3 from 256 MP3 (iTunes Fraunhofer). It's harder to tell apart other tracks but the difference is large enough on many tracks to make the higher bitrate desirable if quality is a concern. (I've done the testing blinded before by the way with LAME-encoded MP3s as well as inferior Xing-encoded MP3s, so it's not just myself imagining things.) ie. IMO, on a lot of music and with a good encoding (and the proper settings), 256 MP3 is almost indistinguishable from CD. 192 is not.

So, even if 128 AAC were as good as 192 MP3 (and many people claim it isn't) then I feel it really isn't good enough for my purposes.

I'd rather "waste" a little space now than decide later I need to re-rip the music. Indeed, for the time being, I'd rather use 256 MP3 than 192 AAC, simply because MP3 has far more support. (My standalone digital audio receiver and my DVD players all support MP3, but not AAC.)

By the way, I was testing using a 100 W/ch receiver with pretty good DACs (fed from a digital signal, not analogue) with Paradigm Monitor or Paradigm Studio series speakers. Not the best system in the world, but I suspect a lot better than some people would be using for compressed audio. Thus, YMMV. If you know you will NEVER use anything but an iPod with earbuds, then 128 AAC might just be fine for you.

[swsteckly]

I'm completely re-encoding my 250cds that I have on my iPod into 320kbps AAC, instead of the 192mbps MP3 that I had before. Inital impressions is that there is a noticable increase in quality, and about a 30% increase in file size. Hardly noticable unless you have a trained ear or exceptional cans.

I notice it distinctly on my Etymotic ER-4P earphones.

Anyway, I've got a lot of CDs to rip before next Tuesday, when my 30GB is to arrive! The only thing I ever use my music on is iTunes (sometimes I burn CDs for the car), or my iPod. AAC is perfect.

[klinux]

Originally posted by cjrivera:
Here's another...

which would have better quality?

mp3 (192kbps) burned to CD (aiff) then ripped to AAC (128 or higher)

or

mp3 (192)?

#2. When you go from one lossy format to another one, the quality will never be as good as the first lossy format.

[klinux]

Originally posted by Eug:

By the way, I was testing using a 100 W/ch receiver with pretty good DACs (fed from a digital signal, not analogue) with Paradigm Monitor or Paradigm Studio series speakers. Not the best system in the world, but I suspect a lot better than some people would be using for compressed audio. Thus, YMMV. If you know you will NEVER use anything but an iPod with earbuds, then 128 AAC might just be fine for you.

Zigzag: I concur with your observation and the source you sited. Stereo Review did such a comparison a while back: reference equipments, professional listening room, double-blind multi-source materials at calibrated levels, and subjects with golden/trained ears. They too concluded 256 kbps are indistinguishable from the CD original.

My advice to most people (who are not audiophile) is that go with the codec that sounds good to you and do not let anyone else influence you. If you are fine with 96kbps AAC, great. If you think you can tell 320kbps FH MP3 from 320 kbps Lame, whatever. Chances are, on the audio equipment that most people here have, I highly doubt you can hear the difference in a controlled test.

***

Eug: I have not doubt that you know more music than most people here but you should know better to write/imply that a "100 w/ch receiver" = quality equipment?!

[Luca Rescigno]

I think the only time you should even consider changing MP3s to AACs (converting directly or through AIFF format, it doesn't matter) is perhaps if you have a bunch of MP3s of 192 kbps or higher, you can convert them to 128 kbps AAC and you'll get equal quality (to non-discriminating ears at least) but less size. So if you're low on space, you could do that. But I'm leaving my library alone, all I'm going to do is re-rip my music in AAC, but no converting for me.

[zigzag]

Originally posted by klinux:
Zigzag: I concur with your observation . . .

[snip]

Eug: I have not doubt that you know more music than most people here but you should know better to write/imply that a "100 w/ch receiver" = quality equipment?!

klinux, I'm glad you concur with me re: AAC, but I would disagree with the assertion that a receiver can't be "quality equipment." I've spent over 30 years buying audio equipment and, after many years of owning expensive separates, I now own a receiver and couldn't be happier. I'd explain my reasoning but I don't want to start an audiophile war.

[Eug]

Originally posted by klinux:
Eug: I have not doubt that you know more music than most people here but you should know better to write/imply that a "100 w/ch receiver" = quality equipment?!

Actually, I said "100 W/ch receiver with pretty good DACs.... Not the best system in the world, but I suspect a lot better than some people would be using". So I never said it was an ultra high end piece, just that my particular hardware was probably better than average. I'd call it mid-end.

That said, I agree with zigzag. I don't see the point of separates any more, unless you have to fill a 50 foot long room or something, or if you're needing to address some other specific problem. For the majority of people, a good quality receiver is fine. Indeed, for MP3 testing purposes, it more than one would need to distinguish 256 MP3 from 192.

I spend my money on my speakers (Paradigm Studio) - much more noticeable difference. (A good set of headphones is also recommended.)

BTW, one of the big issues with MP3 is the type of stereo. With 192 or less, using joint stereo is usually recommended. However, using joint stereo really affects the quality of some tracks. I MUCH prefer normal stereo, but for tha I'd recommend sticking to 224 or higher, because it uses up so many bits. If 192 AAC can match 256 MP3, that's great, but everyone seems to be recommending 128 AAC.

[all2ofme]

Does anyone know much about any possible DRM features that could be enabled at a later date (or that already are, maybe - I haven't read much about all this yet)?

I'd be reticent to use AAC if there's the chance that Apple or a third party could start tying me down my listening/sharing habits in certain ways.

I do all my stuff in 192VBR and while I can tell the difference between the CD and the mp3 it doesn't bother me nearly enough to justify a higher bitrate on my mp3s. When I listen on the sort of headphones I'm happy to carry around and biff into my bag when I'm not using them I can't tell the difference unless I listen closely. On speakers it's quite plain, however.

And this from someone who thought it was quite sensible to go and spend $15k on a stereo only a few years ago

Having AAC give me that quality at a smaller file size might interest me if the above about DRM isn't a potential problem, though.

[slffl]

Think of Mp3 and AAC as pictures. Once compress the original 11MB Tiff image to a jpeg, you can't convert the jpeg back to the original high quality tiff. Burning an MP3 to a CD is not converting it back to CD quality.

Also, someone mentioned an mp3 they ripped at 128kps was larger than an AAC ripped at 128kps. Shouldn't they be the same size?

[klinux]

Oops, I gave the wrong impression, sorry about that. I did not mean to imply that a receiver cannot be a high quality audio equipment. I use a Sony ES receiver myself.

What I meant to say is fine audio equipment is not measured by how many watts per channel they can put out (which I am sure Eug also knows).

[MacNStein]

Eug: I have not doubt that you know more music than most people here but you should know better to write/imply that a "100 w/ch receiver" = quality equipment?!

Yep... Very true. I use an Integra RDC-7 prepro with a 250 w/ch Aragon amp and I can't tell the difference (most of the time) between my Cal Audio CD transport and a 320kps MP3 playing on my PB 12 (using an M-Audio Sonica Theatre)... heck, most of the time I can't tell the difference between CD and 256kps MP3. My stereo speakers aren't junk either (Onix RS-750)... it's all about perceived quality. The truly wiggy audio esotericists will tell you otherwise, but they're just delusional.

[Eug]

Originally posted by klinux:
Oops, I gave the wrong impression, sorry about that. I did not mean to imply that a receiver cannot be a high quality audio equipment. I use a Sony ES receiver myself.

What I meant to say is fine audio equipment is not measured by how many watts per channel they can put out (which I am sure Eug also knows).

The 100 w/ch was simply a descriptor. ie. It's an average 100 w/ch mid-end home theatre Kenwood receiver. The more important part was that it had OK DACs. And I will repeat yet again that I never did say it was a high-end piece.

But even a mid-end receiver is more than enough to demonstrate the differences between MP3 bit rates. It's better than average for playing MP3 though of course.