[andretan]

Most of my music in iTunes are in MP3, and the average file size is 4.3MB I guess, 160kbps encoding.

And I just realised I can only get about 150 odd songs onto my 1GB iPod shuffle. Apple's page says 240 songs on 128kbps AAC.

If I would to convert my MP3s into AAC (No, I won't be re-ripping them from my CDs), would there be a noticeable difference in sound quality? 64kbps AAC or 128kbps?

I'm not "THAT particular" about the quality of my music - am using the stock Apple earbuds and the Sony EX71 (Apple ones for work, EX71 for my train commute)

Thanks

[Krypton]

Unless you have some expensive headphones, or have sensitive ears I doubt you'd know the difference when transcoding.

However, re-ripping from the CDs is fairly painless in iTunes - it's smart enough to work out you already have the files, and keeps the playcount intact.

[andretan]

Actually, how much space will I actually save if I convert a, say, 4MB 128kbps mp3 file to a 128kbps AAC?

[SpaceMonkey]

Originally Posted by andretan

Actually, how much space will I actually save if I convert a, say, 4MB 128kbps mp3 file to a 128kbps AAC?

You won't save anything. The bitrate essentially defines the filesize (think about what you're actually saying when you say kilobytes PER second). 128kbps audio files of equal length will always be the same size.

Personally, if you're not planning on re-ripping, I'd just stick with your mp3s. I don't think going from 160 to 128 will save you that much space anyway. Keep in mind that Apple's estimated capacity for the iPod is based on like a 3-4 minute average song. If you have a lot of tracks that are longer than that, you won't get close to their estimated maximum anyway.

[lenox]

When Apple added AAC encoding/decoding to iTunes, I noticed a decent drop in cpu usage compared to mp3. Maybe this means it will save you battery life on your ipod?

[legacyb4]

If you could go from CD down to 128 AAC, then I'd say go for it and squeeze out the few extra songs you could get if you have the time.

Otherwise, no point in recompressing MP3 to AAC; also, syncing the shuffle already allows for that option to convert higher bit rate songs to 128/AAC automatically although it does slow down the sync time.

Originally Posted by andretan

If I would to convert my MP3s into AAC (No, I won't be re-ripping them from my CDs), would there be a noticeable difference in sound quality? 64kbps AAC or 128kbps?

[Hodog16]

I wouldn't recommend going below 128kps for bitrate from past experience, unless the most important thing is quantity > quality.

And AAC and MP3 files of the same bitrate are identical in size.

[andretan]

Thanks you guys for the advice.

I think I'll just stick to what I have for now.

My iBook only has USB 1.1 so syncing by itself is already slow enough, so I don't think I'll wanna do compression on the fly.

[mpancha]

I made the mistake of switching to AAC buying Apple's hype about better sound quality with less file size, at some point I'm going to have to find an AAC -> MP3 encoder just so I can undo this mess without having to re-rip all my CDs to MP3.

[ApeInTheShell]

I went down to 96kbps AAC and it takes up less space on my iPod. I only have a couple albums that are Apple Lossless. The sound quality is great but if you are picky stick with 128kbps. I was on the bus the other day and there was a kid with a Mini. Of course, he had the volume all the way up but that has more to do with bad hearing i guess.

[Chuckit]

Originally Posted by mpancha

I made the mistake of switching to AAC buying Apple's hype about better sound quality with less file size, at some point I'm going to have to find an AAC -> MP3 encoder just so I can undo this mess without having to re-rip all my CDs to MP3.

Apple's "hype" is the truth. But as people have said, converting lossy-to-lossy (MP3 to AAC or vice-versa) will decrease the sound quality because you'll get keep the sound loss from the first encoding and get more from the second.

iTunes can convert AAC to MP3, but like I just said, that will just decrease the sound quality even further.

[B Gallagher]

Originally Posted by ApeInTheShell

I went down to 96kbps AAC and it takes up less space on my iPod. I only have a couple albums that are Apple Lossless. The sound quality is great but if you are picky stick with 128kbps. I was on the bus the other day and there was a kid with a Mini. Of course, he had the volume all the way up but that has more to do with bad hearing i guess.

You're kidding right? 96kbps AAC/MP3/anything else might be fine if you just want to listen to the songs on your headphones.. but try running any song at that quality through a decent set of speakers. Then, if you have the CD original, listen to that on some good speakers (not your headphones) to compare the difference. I think you'll be surprised at the difference in quality.

Each to their own of course.

[ort888]

There is an option on the shuffle to convert all transfered songs to 128 bit AAC as they transfer over. Why not just do that?

[andretan]

Originally Posted by ort888

There is an option on the shuffle to convert all transfered songs to 128 bit AAC as they transfer over. Why not just do that?

How about reading Post #8 ?

[Randman]

Compression on the fly isn't going to take much longer when syncing via USB 1. What Mac are you using to sync?

[andretan]

Originally Posted by Randman

Compression on the fly isn't going to take much longer when syncing via USB 1. What Mac are you using to sync?

Am using a G3 700 iBook.

Syncing about 900MB worth of songs takes me about 20 minutes or so.

[jamil5454]

Originally Posted by andretan

Am using a G3 700 iBook.

Syncing about 900MB worth of songs takes me about 20 minutes or so.

It won't take much longer than that. Besides, there is a simple solution to this problem: Start it, then go get ready for work, then come back and it's done!

[Sosa]

I'll tell you what really sucks about using AAC... not being able to play them in you expensive car MP3 stereo! Doh! All the songs I purchased from iTunes are in AAC and cannot be played in my car unless I record them in audio format, which defeats the purpose of the MP3 radio in the first place.

I've read that iTunes allows you to convert songs back to MP3 from AAC, but I haven't figured out how.

[climacs]

i use aac for music ripped from my CD library or streams recorded from the web (i record tons of dj mixes and burn to CD for the car plus convert to AAC for iPod and iTunes), encoded at 160kbps, which is higher than necessary I know

of course 99% of the stuff I download is MP3, I always try to grab 192 or better

i have not tried converting an mp3 to aac or vice versa but I know enough about compression to know it's generally not a good idea to re-compress a compressed file. You won't save much room (none, if the bitrate is the same) but it will degrade the sound quality even further.

[Hodog16]

All the songs I purchased from iTunes are in AAC and cannot be played in my car unless I record them in audio format, which defeats the purpose of the MP3 radio in the first place.

Only bet really is to burn a playlist of purchased songs off itunes and then re-import them as mp3's so you can play them in your radio.

[Bobby]

Originally Posted by andretan

Actually, how much space will I actually save if I convert a, say, 4MB 128kbps mp3 file to a 128kbps AAC?

Actually I did this with around 200 CDs back when Apple first introduced AAC, and I LOST quite a bit of space... It was a direct replacement of 128kbps MP3 to 128kbps AAC... I would estimate the 128 MP3 to 128 AAC averaged from 5% to 8% larger average per song in my library...

[Roehlstation]

I saved over 2 GB of space on my 12,000 songs

[pastusza]

Of all the different compressed audio formats out there now, MP3 is probably the worst AT LOW BITRATES. So, at 128K, AAC, Ogg, WMA, and MP3Pro are all going to sound better than vanilla MP3. I personally try to avoid any MP3 file that is below 192K bitrate. If your needs are ony to play then on your iPod and your Mac, AAC is a good choice.

Since I use my iPod in the car also, AAC is a good choice for me.

It's just too bad I can't use AAC files on my Palm.

[macslut]

Originally Posted by Bobby

Actually I did this with around 200 CDs back when Apple first introduced AAC, and I LOST quite a bit of space... It was a direct replacement of 128kbps MP3 to 128kbps AAC... I would estimate the 128 MP3 to 128 AAC averaged from 5% to 8% larger average per song in my library...

Unless your iTunes library was traveling at a speed approaching the speed of light, what you're describing can't be correct.

It's 128 kilobits per second. Bits is bits, it doesn't matter what the format is. A 128kbps file is going to be the same file size regardless of format.

If you want to figure out how much changing from one bitrate to another will save/cost you the math is as follows:

A= B * (y/x)

Where:
A = answer
B = file size
x = original bitrate
y = resulting bitrate

Now as someone who has a 400GB hard drive for my iTunes library, let me strongly suggest re-ripping your collection in AAC. The quality per k is going to be much better, especially if you're going for lowend bitrates of 128kbps.

I have my collection ripped at 192 AAC. This is pretty darn good quality on my stereo system and still sounds great for when I need to convert to MP3 for various weird devices that I have.

I just wish they would hurry up and release AAC+ (HE-AAC)

[one09jason]

Originally Posted by macslut

It's 128 kilobits per second. Bits is bits, it doesn't matter what the format is. A 128kbps file is going to be the same file size regardless of format.

(I retract my earlier statement.)

With a little experimentation, I discovered that 128 kbps AAC files encoded from a CD by iTunes are in fact slightly larger than 128 kbps MP3s encoded from the same CD. So losing space in MP3 to AAC conversion is possible. Perhaps there is a bit more overhead with the AAC format, even though the same amount of data is being stored.

[climacs]

the space saving comes from the fact that a 128kbps AAC file will sound as good as or better than a 160kbps MP3.

So, you can rip your CDs to AAC at a lower rate than you would an MP3 (saving space), or encode to AAC at the same rate as you would the MP3, and get higher quality for approx. the same file size.

[unother]

I think many are comparing apples and oranges here (no pun intended).

The fidelity of an AAC 128k file is known to be equivalent to an MP3 at 320k encoding. It is not file-size, per se, that you are concerned about when discussing equivalent encoding rates; it's quality. All else being equal, an AAC 128k file will sound much better than an MP3 128k file, whether or not the file-size is equivalent. As for converting AAC to MP3 or vice versa: if you re-encode a lossy codec to a lossy codec (as others have pointed out) you will make it sound worse.

The best solution? Also the most laborious, but the best for fidelity: re-rip the original CDs. If you have the HD space, do both ALAC (Apple Lossless) and 128k AAC. Use the AAC files on your iPod, and the Lossless files for playing music from your computer.

If HD space is a premium, and fidelity is not as much of a concern, well, re-rip the CDs at AAC 96k. Then you will have saved space while not reducing quality below what the original MP3 160k files were.

For the record, I have all my CDs ripped in two formats: ALAC (for listening thru my monitors at home) and AAC 192k (for my iPod photo).

[SpaceMonkey]

Originally Posted by unother

I think many are comparing apples and oranges here (no pun intended).

The fidelity of an AAC 128k file is known to be equivalent to an MP3 at 320k encoding.

Huh? Maybe you perceived it to be, but it's not known to be anything of the sort. Gauging the fidelity of a file format of bitrate X versus another file format of bitrate Y is subjective. I personally find (and many other listening tests that I've seen on the internet conclude similarly) that 128kb/s AAC files sound more like 160kb/s MP3 files, assuming you're using a high quality MP3 codec (such as some version of LAME).

But whatever works for you.

[dougalzene]

A couple of posts queried how to convert AAC to MP3, using iTunes. Go to preferences in the edit menu:

- To just burn a selection to CD in MP3 format: Go to "Burning" and Select "MP3 CD" - that's it.

- To convert a selection from AAC (or other format) to MP3: Go to "Importing" and Select "Import Using -- MP3". By default it will choose 160kbps although you can change this. Then all you need to do is make your selection and rt-clk to "Convert Selection to MP3".

It really doesn't get more straightforward than that!

Two things to remember about the second option - any subsequent songs ripped/imported into iTunes will be MP3 until you change back AND converting will add a MP3 version, the AAC copy remains until deleted.

[ashley_easter]

i use aac for music ripped from my CD library or streams recorded from the web (i record tons of dj mixes and burn to CD for the car plus convert to AAC for iPod and iTunes), encoded at 160kbps, which is higher than necessary I know

of course 99% of the stuff I download is MP3, I always try to grab 192 or better

Here, here! Yeah, I find that 160kbps MP3 is ≈ 128kbps AAC, but I'm a fussy bugger and I encode at 192 MP3 or 160 AAC. You can notice the difference at high volumes on good speakers. And I figure anything that will give my crappy car stereo a head start is a good thing, so I go a bit overboard. Then again, some people routinely encode using Apple's Lossless codec!

160kbps AAC = what I think is the best size vs quality. Agree? Disagree?

[Randman]

160 AAC would be sweet.

[irchs]

I would not recommend trans-coding your MP3 files to AAC. Both codecs are lossy, meaning they lose data in order to compress the audio. I am pretty sure MP3 and AAC "lose" different parts of a waveform, meaning you potentially lose a greater set of information compared with re-ripping from a CD.

No one should ever trans-code.

Jan

[irchs]

On a note relating to the thread however, AAC is a far superior codec to MP3, and if given the choice, everyone should choose AAC

Jan

[Squozen]

I use 192kbps AAC for my iPod and Apple Lossless for home.

[vasic]

I am a professional musician (more than 20 years). Still can hear 20khz. I have 350 songs on my Shuffle. This is the result of careful testing (in a recording studio) of various codecs/bitrates. The short of it is - I always use AAC 96k for my iPod.

The (bit) long(er) of it: after comparing 192k, 128k, 96k using both AAC and MP3, I found that:

1. AAC has consistently produced better sound quality, at same bitrates, than MP3;
2. The quality difference between AAC and MP3 was barely noticable at high bitrates, however became much more pronounced as bitrates decreased;
3. File size of AAC was slightly higher than MP3 for the same bitrate.
4. The audio quality of AAC 96k was still surprisingly good and, for purposes of commuting, outdoors activity and other noisy environments, just perfect.
5. Finally, tests were done using jazz (Diana Krall, live in Paris), classical (Tchaikovsky, symphonies; Bach, Brandenburg concertos), as well as some contemporary stuff (Metallica, Clapton, etc.).

Unless you are listening to your music while fishing (that is, catching fish, not phishing for credit card numbers...), and focusing on the music and nothing else, you won't notice the quality loss in 96k. Instead of putting some 900 minutes on a 1GB shuffle, you'll be able to put some 1300 minutes (almost 22 hours).

That's what I have to say about that.

[macslut]

Originally Posted by one09jason

(I retract my earlier statement.)

With a little experimentation, I discovered that 128 kbps AAC files encoded from a CD by iTunes are in fact slightly larger than 128 kbps MP3s encoded from the same CD. So losing space in MP3 to AAC conversion is possible. Perhaps there is a bit more overhead with the AAC format, even though the same amount of data is being stored.

Just to be clear at the expense of beating a dead horse,

bits per second = bits per second, and always will

You will find rounding errors, and slight variations in file size due to data chunk processing and file overhead, but this should be insignificant...really, really insignificant. I (unfortunately) have to transcode on a daily basis. The largest file discrepancy on my 400GB library of AAC and MP3s comes in at 0.8457%

If you're finding significantly higher discrepancies, then you might want to look at using a different encoder.

[dannyillusion]

Am I the only one who rips songs in 320kbps AAC?

[lavar78]

Originally Posted by dannyillusion

Am I the only one who rips songs in 320kbps AAC?

Why do you do that?

[wulf]

Originally Posted by dannyillusion

Am I the only one who rips songs in 320kbps AAC?

Possibly. But then, I know an audio engineer whose 40GB iPod only has a few albums on it because he insists on keeping them all in Lossless format

I myself (being a bit mutton), find that 160AAC is more than adequate

[siflippant]

Originally Posted by wulf

Possibly. But then, I know an audio engineer whose 40GB iPod only has a few albums on it because he insists on keeping them all in Lossless format

I myself (being a bit mutton), find that 160AAC is more than adequate

192 AAC here...

[Busemann]

Originally Posted by dannyillusion

Am I the only one who rips songs in 320kbps AAC?

320kbps is just stupid.

There's very little difference in quality compared to 192kbps (that is, artifacts at 192kbps will almost definitely be there at 320kbps as well) and it's not as good as Lossless (which is just twice the size).

It's much smarter to use 192kbps for most stuff and lossless for the albums you cherish most dearly (works as a perfect backup so you can use the cd's as coasters or something )

[Russian Mac fan]

Yes, you can play AACs on your Palm. I think either TCPMP and PocketTunes can play AACs

[Russian Mac fan]

Out of my 23 gig ITunes library I have about 4 gig encoded in AAC at 96 -- mostly jazz and albums I don't care that much about

[iLikebeer]

Originally Posted by Randman

Compression on the fly isn't going to take much longer when syncing via USB 1. What Mac are you using to sync?

Originally Posted by Roehlstation

I saved over 2 GB of space on my 12,000 songs

These 2 reasons are why I encode everything in Apple Lossless now. You can re-encode on the fly, which will only get faster and faster as technology improves.
Saving 2GB really isn't that impressive when you consider harddrives are at about $1/GB and will only get cheaper. I plan on keeping all of my music forever and would rather have it all lossless now with a tiny bit of space inconvenience rather than have to rerip all of my CD's a few years down the road when storage space doesn't really matter.

[macmad]

If you're serious about your music, and if you're tired of re-ripping all your CD's whenever the next codec comes out (or upgrade your hi-fi), then use a lossless format. Apple Lossless is very convienient because its in iTunes. You'll probably also want an additional copy at 96-128kb/s AAC for the iPod.

I have re-ripped my music too many times! Disk drives are cheap, so rip it once!

[Mithras]

Eh, disks aren't so cheap.

[cleanup]

Eh, I'm an old-fashioned, picky guy. I only have a 4GB mini, and about 1 gig left on it. Most of my songs are 128-192 MP3. When I purchase new songs from allofmp3.com, they're all 192 kbps MP3. I don't buy this higher quality at lower bitrate mumbo jumbo.

[sieb]

Doesn't AAC preserve 5.1 Dolby and all that jazz if you rip from the original? IIRC MP3s only support stereo. In which case, going from mp3 to aac won't gain anything, only if you re-rip from the original to AAC. I'm not an audiophile so I leave everything as MP3s for cross compatability, sounds fine to me.. *shrug*

[Glenn The Podder]

Just use the option to compress tunes to 128kbps when you transfer to the Shuffle.

[ibookuser2]

Originally Posted by sieb

Doesn't AAC preserve 5.1 Dolby and all that jazz if you rip from the original? IIRC MP3s only support stereo. In which case, going from mp3 to aac won't gain anything, only if you re-rip from the original to AAC. I'm not an audiophile so I leave everything as MP3s for cross compatability, sounds fine to me.. *shrug*

You're confusing AAC with AC3, which is used on DVDs for digital audio. As far as I know, AAC doesn't support more than two channels (unless you just use a bunch of mono AAC streams) and iTunes most definitely doesn't; nor do any standard audio CDs.