Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Comparable AAC VS MP3 Qualities? (Read 11963 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Comparable AAC VS MP3 Qualities?

I am by no means an audiophile, so I thought I'd ask people who are some questions I would like answers to.

I've been using MP3's since I got my first audio file player back in 2001.  I ripped all my CD's and then whatever music I downloaded from various sources into CBR 160 kbps quality.  I switched over to using ipods in 2005 and never plan on going back.  (Unless someone comes out with a player that can COMPLETELY blow ipods out of the water!)  Since AAC is the ipod's(itunes) native format and I read that AAC has much better quality @ the same bit rate compared to MP3's (without much more file size), I tinkered with the idea of switching formats.  After ripping a CD album into AAC, then comparing it to the same MP3 album, it sounded MUCH better in comparison.  So that was it!  I re-ripped all my CD's/downloads into AAC-LC @ CBR 160 kbps. 

Finally after telling you all that, here are my questions:  In the AAC quality that I have my music at now (AAC-LC @ CBR 160 kbps), what bit rate would be comparable to this in MP3?  I ask this since most of the music albums I download are in MP3 format (usually around 256 kbps or higher).  I then back them up by burning the downloaded albums on CD-R's as audio CD's.  I then rip those burnt CD's into the formentioned AAC format for my music file collection.  (Using dbPoweramp/Nero AAC encoder)  Is this a good way to do it?  Is there any loss of quality between burning the downloaded MP3's to an audio CD, then ripping them into AAC?  Should I just convert the downloaded MP3's straight to AAC?  Does it matter? 

Comparable AAC VS MP3 Qualities?

Reply #1 –
Quote
Finally after telling you all that, here are my questions:  In the AAC quality that I have my music at now (AAC-LC @ CBR 160 kbps), what bit rate would be comparable to this in MP3?  I ask this since most of the music albums I download are in MP3 format (usually around 256 kbps or higher).  I then back them up by burning the downloaded albums on CD-R's as audio CD's.  I then rip those burnt CD's into the formentioned AAC format for my music file collection.  (Using dbPoweramp/Nero AAC encoder)  Is this a good way to do it? Is there any loss of quality between burning the downloaded MP3's to an audio CD, then ripping them into AAC?  Should I just convert the downloaded MP3's straight to AAC?  Does it matter? 

You're doing it about the worst way possible, actually. 

Transcoding from MP3 to AAC is introducing a guaranteed quality loss that dwarfs whatever quality differences exist when ripping from CD to either of these formats. Burning to CD doesn't solve any of this - it just means that you've lost the MP3 originals, which are far more valuable than the uncompressed CD audio.

In my experience, I accidentally transcoded a 128kbps AAC file back through 128kbps AAC, and the results were hideously audible - far far worse than the original AAC, and didn't require an ABX. Most people who have tested such things here mirror that experience. Reencoding a lossy file, even at a relatively high bitrate, and especially with CBR, runs a very high risk of audible distortion.

If you don't have your original MP3 downloads - only the audio CD backups and the AAC transcodes - you're screwed. You'll need to buy/download them again to get the quality back.

In response to your original question comparing 160kbps AAC to MP3: at those bitrates it's very hard to generalize, but one thing that is for certain is that VBR is superior to CBR in all situations. For that matter, at those bitrates, there are known issues with specific AAC/MP3 encoders that matter just as much (or more) than any intrinsic qualities of the format.

Comparable AAC VS MP3 Qualities?

Reply #2 –
Burning MP3 to CD-DA and then ripping them to AAC cannot be better than plain transcoding from MP3 to AAC.
And, look at this page: http://wiki.hydrogenaudio.org/index.php?title=Transcoding:
Quote
Transcoding between lossy formats is therefore generally not recommended. The sound quality of the result will always be worse than the (lossy) source file.

Comparable AAC VS MP3 Qualities?

Reply #3 –
A few answers/corrections:

1) Transcoding MP3 to AAC will always reduce quality, no matter what the bitrates involved are.  If your source file is MP3, it should stay MP3.  You can't recover the lost information

2) MP3 quality varies by encoder.  The MP3 encoder you were using in 2001 is inferior to a modern day MP3 encoder like LAME.  Depending on which encoder you used, it may range from drastic quality differences (Blade, Xing) to subtle (FhG)

3) At the bitrates you're using, it would be more accurate to claim that AAC achieves transparent quality at a lower bitrate.  At much lower bitrates (<96kbps), the claims of superior quality are more warranted.

Comparable AAC VS MP3 Qualities?

Reply #4 –
Quote from: Hectic on
After ripping a CD album into AAC, then comparing it to the same MP3 album, it sounded MUCH better in comparison.

Hearing that much difference at those bitrates is generally not expected, and could indicate that the MP3s were from a low-quality encoder.

Edit: benski beat me to it.

Comparable AAC VS MP3 Qualities?

Reply #5 –
You've also ignored/not noticed one of the finest attributes of the LAME MP3 encoder. Variable bitrate (VBR) encoding, which it's been highly optimised for over the years.

Forcing any MP3 encoder to encode at less than 320Kbps will almost always lose you something in terms of sound quality. Always encoding at 320Kbps results in unnecessarily large files as 320Kbps is only required some of the time. Allowing LAME to do its job properly in VBR mode can result in files half the size of 320Kbps which are indistinguishable from 320Kbps CBR to almost everybody nearly all of the time.

I personally have never been able to tell the difference between CBR320 and VBR at -V3 (~175Kbps), regardless of how expensive the playback equipment was that was being used at the time. Even with an average bitrate as low as ~175Kbps in VBR mode, LAME is still perfectly capable of using 320Kbps on occasions when it sees fit to do so.

I'd suggest that you read the Hydrogenaudio LAME WIKI for some up-to-date facts on where LAME encoded MP3 has got to today.

Cheers, Slipstreem. 

Comparable AAC VS MP3 Qualities?

Reply #6 –
I have one question: did you actually ABX the difference between mp3 and AAC or did you just click between songs?  You would be much better off enabling VBR encoding for your AAC files.  Either use iTunes AAC or Nero AAC, both should provide you with quality CD rips.  You need to enable VBR encoding with iTunes AAC or use one of Nero's -q presets.  That way you get the most out of both encoders.  There is no need, today, to encode an AAC file in CBR mode.  I have yet to come across a device/decoder/application that will play CBR AAC files but won't play VBR AAC files.  Some people have run into that problem with mp3 (I think the devices were older though) but not with AAC.

On top of that, what made you go with the 160kbps bitrate?  Did you conduct blind ABX tests to determine that is the bitrate for you?  Past listening tests have shown that both iTunes and Nero AAC perform very well at the 128kbps VBR bitrate range and many, many people have a hard time distinguishing between that and the source CD.

Comparable AAC VS MP3 Qualities?

Reply #7 –
To the OP:

You transcoded 256kbps MP3 to 160kbps CBR AAC?  That's an awful thing to do.

Anytime you transcode from one lossy format (MP3) to another (AAC), you lose significant audio quality.  Especially if you are transcoding at a lower bitrate (256kbps CBR/VBR -> 160kbps CBR). 

Burning the MP3s to CD audio and then ripping that CD to AAC won't make a bit of difference in improving the audio quality.  In fact, it may make it even worse because burning and then re-ripping introduces several chances to have the audio modified without you knowing it (slight errors in burning the CD audio and then slight errors in ripping that custom made CD).

You'd be better off leaving the MP3 files as MP3s and only encoding the actual commercially made CDs you do have to AAC.  For those commercial CDs, select 160kbps VBR AAC (not CBR) for practical transparency.

Comparable AAC VS MP3 Qualities?

Reply #8 –
Explanation why lossy-lossy transcoding must always result in worse quality, for dummies:

Take a sheet of paper.

Now tear a small piece off it - thats the mp3

Now tear one more piece off it - thats the AAC file transcoded from mp3
I am arrogant and I can afford it because I deliver.

Comparable AAC VS MP3 Qualities?

Reply #9 –
I wonder when will video people start to understand this simple truth about transcoding (and stop calling their poor quality rips 'backups').

Comparable AAC VS MP3 Qualities?

Reply #10 –
Dayumn. I guess he's gone now.

Comparable AAC VS MP3 Qualities?

Reply #11 –
The AAC advantage is in the sub 128 k bitrates. I really don't believe there is any difference at higher bitrates except for those specific mp3 cases (I guess it could count there). There is little evidence to suggest AAC 160k is perceptualy superior to Lame -V3 .

Comparable AAC VS MP3 Qualities?

Reply #12 –
Well again, I don't know any of this, so that's why I asked!      So, to clarify:

1.  I should stop ripping my AAC files from the back-up MP3 to CD-DA CD's I burn and just transcode them straight from MP3 to AAC?  (I know a number of poster-repliers said it's just best to keep them in the MP3 format, but I want my files to be a unified, 1 format.)  Honestly, at first I was weary about doing it this way (for MP3 downloads) so I listened to the original MP3, then the AAC file and didn't HEAR any quality difference.  (Although it may actually exist)  So should I just burn the MP3's straight to disc as-is or is it still OK to back them up in the CD-DA format?  (That way, they'd at least be readable in any old CD player, which is why I do it that way)  I mean, burning the MP3's into the CD-DA would just mean that the quality of the disc is only as good as the quality of the MP3's, but there wouldn't be any quality loss would there?

2.  Stop ripping in CBR...why?  From what I know (correct me where I'm wrong here), all VBR does is just save you a little file size.  VBR just takes the less complex and silent portions of a song and gives them less space in the file?  Give me an understandable, really good reason to stop CBR and start VBR and I'll probably take the time to do it.  (It's summer time and I'm between college semesters right now, and with my job being early morning, I pretty much have all day to do whatever; so time is no problemo!)  If I were to change my music collection from CBR to VBR, would it make enough of a difference to completely re-rip all my CD's and redownload what I can OR just transcode the CBR files to VBR?  (Probably the former right?)

-j7n & Lyx:    Your smart-ass responses aside, you didn't EXPLAIN why MP3 to AAC results in so much quality loss!  (Which again, I can't hear)

-kornchild2002:  I chose 160 quality for AAC just because it was the bit rate I used in the MP3 format.

-benski (& pdq):  Again, what actually happens in the transcoding process from MP3 to AAC to lose quality?  You may be correct about the poorer MP3 quality album when I compared it to the newly ripped AAC album.  I probably chose one of the first CD's in my case to rip into AAC, which are some of my oldest discs, and therefore my oldest ripped MP3 albums as well.  I forget what program/encoder I used back then, but yeah, I'm sure it was inferior to todays.  I am however going to stick with the AAC format now no matter what.

Thanks for the info so far everyone and I look forward to reading your suggestion to this reply's questions! 

Comparable AAC VS MP3 Qualities?

Reply #13 –
Quote from: Hectic on
1.  I should stop ripping my AAC files from the back-up MP3 to CD-DA CD's I burn and just transcode them straight from MP3 to AAC?  (I know a number of poster-repliers said it's just best to keep them in the MP3 format, but I want my files to be a unified, 1 format.)  Honestly, at first I was weary about doing it this way (for MP3 downloads) so I listened to the original MP3, then the AAC file and didn't HEAR any quality difference.  (Although it may actually exist)  So should I just burn the MP3's straight to disc as-is or is it still OK to back them up in the CD-DA format?  (That way, they'd at least be readable in any old CD player, which is why I do it that way)  I mean, burning the MP3's into the CD-DA would just mean that the quality of the disc is only as good as the quality of the MP3's, but there wouldn't be any quality loss would there?

Transcoding straight from MP3 to AAC will have the same effect as ripping CDs you burned from the MP3.  Burning/Ripping, however, adds an additional chance of errors from scratched CDs, etc.

Quote
2.  Stop ripping in CBR...why?  From what I know (correct me where I'm wrong here), all VBR does is just save you a little file size.  VBR just takes the less complex and silent portions of a song and gives them less space in the file?  Give me an understandable, really good reason to stop CBR and start VBR and I'll probably take the time to do it.  (It's summer time and I'm between college semesters right now, and with my job being early morning, I pretty much have all day to do whatever; so time is no problemo!)  If I were to change my music collection from CBR to VBR, would it make enough of a difference to completely re-rip all my CD's and redownload what I can OR just transcode the CBR files to VBR?  (Probably the former right?)

Some early VBR implementations worked this way.  Modern implementations of VBR strive to maintain consistent quality changing the bitrate on a frame-by-frame basis.  The LAME MP3 encoder, for example, will use bitrates between 32kbps and 320kbps.  If you use 160kbps CBR, the sound quality will be lower than VBR in spots where more than 160kbps is "required" to maintain sound quality.

Quote
-benski (& pdq):  Again, what actually happens in the transcoding process from MP3 to AAC to lose quality?  You may be correct about the poorer MP3 quality album when I compared it to the newly ripped AAC album.  I probably chose one of the first CD's in my case to rip into AAC, which are some of my oldest discs, and therefore my oldest ripped MP3 albums as well.  I forget what program/encoder I used back then, but yeah, I'm sure it was inferior to todays.  I am however going to stick with the AAC format now no matter what.


When a psychoacoustic coder (e.g. MP3 or AAC) encodes audio, it must make decisions on where to compress.  Tt gives full precision to some sections of the audio spectrum and less precision to others.  When you apply a second encoder, it must make these decisions again, and there are no guarantees that it will be the same.  The second pass might reduce precision in areas that were previously high-precision, and keep unncessary precision in areas that previously had low precision.  The problem is exacerbated further when you use a different format entirely (like AAC instead of MP3) as the number of spectral bands differ as does the number of samples per frame.

Comparable AAC VS MP3 Qualities?

Reply #14 –
I am by no means an expert but here it goes:
1.  Yes.  You serve no purpose by ripping the CDs that you burned from mp3 files.  The quality could potentially be better if you just transcoded your mp3 files directly to AAC.  You see, you could be introducing more errors by going the CD route.  Let's look at the procedure for the CD route (I will put an * any place an error can come up): you have the mp3s, you burn them to an audio CD (*), you then store that audio CD (*, scratches), then you rip that audio CD later down the line (*).  That is three spots where error can be introduced.  Let's look at the procedure for directly transcoding (again, I will mark all the spots where error can be introduced): you have the mp3 file and convert it to AAC.  Wow, isn't that a lot shorter and has less errors?  Errors can always be introduced during the lossy encoding process if you overload a processor or are accessing the hard drive using a different program at the same time.  Even then, you shouldn't have any issues.  It is true than an audio CD burned from mp3's will have the exact same quality as the source mp3s.  However, that is not an effective way of lossy to lossy transcoding.  You might as well just convert the files.  You can continue to burn audio CDs using your mp3 files though as they will retain higher quality over your transcoded AAC files.

2.  Why?  It is not that I can't think of an answer but there are too many reasons why one should rip using VBR.  VBR not only uses a lower bitrate in some parts but it also uses a higher bitrate in some parts as well.  Both Lame mp3 and Nero AAC have been tuned for VBR encoding.  Why are you going to choke down an encoder just to get CBR files?  That would be like getting a new Ford Mustang GT and then putting a governor in it capping the speed limit to 30 MPH.  What's the point?  I don't know if the difference between CBR and VBR would be worth re-ripping your CD collection.  I think it is but others may disagree.  I certainly wouldn't transcode any CBR files to VBR though.  Then again, I would never transcode between lossy audio formats.

Going from mp3 to AAC may in fact reduce the quality enough for j7n and Lyx that they recommend not to do it.  Do you really know if you can't hear a difference?  Are you conducting a blind ABX test or just switching between tracks?  If you are actually conducting a blind ABX test then alright.  Your claims go right out the window if you are just switching between tracks.

As for your use of the 160kbps CBR bitrate, that really isn't a good answer.  You should conduct a blind ABX test to determine which bitrate is appropriate for you.  For all you know, 128kbps VBR (always use VBR, CBR provides no benefits over VBR other than a known file size but that is what you use ABR for) would be more than enough for your ears.

What is so bad about going from mp3 to AAC?  First off, mp3 is a lossy format.  This means that audio information is completely thrown away (and can never be retrieved) and the remaining audio information is compressed (it can never be uncompressed).  This hold true for any lossy format such as mp3, AAC, WMA, and OGG.  So, when you transcode between lossy files, you will be compressing something that has already been compressed.  So you take that already compressed mp3 and encode it to AAC.  Not only will the AAC encoder re-compress the mp3 file but it will throw away even more information.  Think of it like this: you have an original oil painting and you have a picture that you took with a digital camera.  Which one will give you the best experience?  The original oil painting will give you the better experience while the picture is just a cheap copy.  In this case, your mp3 files represent the oil painting and the AAC files represent a digital picture.  I am not talking about prints here but you standing in front of the painting and taking the picture.

I suggest that you do some further research by browsing around here on Hydrogenaudio and look at HA's wiki as well.  I also suggest that you look into the Lame mp3 encoder as it can achieve the same quality as Nero AAC and iTunes AAC at about the same bitrates.  In my opinion; Nero AAC, iTunes AAC, and Lame mp3 all sound alike at 160kbps VBR and above.  Do the research for yourself and conduct your own blind ABX tests.  Use a bitrate that your ears find transparent, don't use a bitrate just because you used it in the past.  I used to rip at 64kbps using Xing's mp3 encoder (this was back in 2001 when I didn't know any better and I had a 32MB Rio 600 with a 64MB add-on) but I wouldn't even think about using the 64kbps bitrate with Lame mp3, Nero AAC (unless it was HE-AAC), or iTunes AAC.

The reason why you were getting some negative replies is because your way of thinking goes against the ideas of this website.  You choose an arbitrary bitrate based on nothing, you want to transcode your mp3 files to AAC, and you are encoding using CBR for the wrong reasons.

Edit: Damn, benski beat me to it.  I guess I spent too long writing up my reply.

Comparable AAC VS MP3 Qualities?

Reply #15 –
So some background on why CBR was recommended so long ago and VBR is recommended now...

Good VBR implementations require a good model of human hearing (psymodel) to maintain constant quality during an encode. In MP3's infancy most encoders did not have good psymodels, or didn't support VBR at all (early Xing? 8hz? very early LAME?) and so it was considered safer to encode to high bitrate CBR. But psymodels have been in really good shape for at least 6 years (since LAME 3.90.3). It's no longer a valid reason to keep using CBR, and in fact, if you use a CBR bitrate under 320kbps, you're far more likely to get worse quality than using VBR at a much lower bitrate.

Why do you care about a unified format? All music players - and certainly all iPods - can mix and match formats perfectly well. And the MP3/AAC/CD-ROM formats are going to be readable for decades into the future - probably just as long as CD-DA will be readable - so you don't buy anything from decoding to CD-DA yourself, except a loss of CD space and reduced error correction.

Comparable AAC VS MP3 Qualities?

Reply #16 –
benski, kornchild2002, Axon,

OK guys, thanks for explaining all that!  That will really help me out in making some decisions.  The first of which; I'm going to hunker down and re-rip all my CD's to AAC VBR.  I'm not sure at what quality yet, but I'll decide when I start to rip.  As for doing the blind ABX test, to be honest...I have no idea what "ABX" means!?

As for all my downloaded stuff, well I guess it's a mixed blessing.  Most of the music in my collection is from the actual commercial CD's (about 70%) and the rest are the downloads.  Luckily the place I mostly download from will let me download whatever I buy a couple of times and they keep a complete history with download links for anything I ever bought, so most of it I can redownload.  (But not all)  But really, if I was THAT CONCERNED about having good quality for the albums I downloaded, I would have bought the CD's for them instead, so no BIG deal.  I may re-download and transcode some, or all of it, or I may just leave them as-is.  (In MP3)  I'm just not sure yet. 

I almost wish I didn't even ask any of this, so I could have remained blissfully ignorant.  Oh well, you can't put the genie back in the bottle.  I guess it is best that I do know this stuff so I won't have the illusion of a good quality music collection.  It's going to be some work though! 

Well, I'm going to go out in an hour or so to get the new "Disturbed" album and once I get back, I guess I'll get started! 

Comparable AAC VS MP3 Qualities?

Reply #17 –
Quote from: Hectic on
I almost wish I didn't even ask any of this, so I could have remained blissfully ignorant.  Oh well, you can't put the genie back in the bottle.  I guess it is best that I do know this stuff so I won't have the illusion of a good quality music collection.  It's going to be some work though!

There is something to be said for blissful ignorance, I suppose, and along those lines I should point out one drawback of doing serious ABX* testing. If one spends some time training oneself to hear the small differences (artefacts) among high-quality encodings, you might find that you can never go back, i.e. from then on you will be sensitized to hearing those same artefacts. At that point you will find that you need even higher quality encodes and larger files to make your music listenable again.

I myself have never gone out of my way to hear defects in the music that I listen to and so far do not have the problem of encoder inflation.

*ABX - a formalized methodology of double-blind listening testing to prove that one can actually hear a difference between two encodings. It is designed to eliminate the placebo effect.

Comparable AAC VS MP3 Qualities?

Reply #18 –
Quote from: Hectic on
But really, if I was THAT CONCERNED about having good quality for the albums I downloaded, I would have bought the CD's for them instead, so no BIG deal.
Any MP3 encoding that you can download that's been encoded with the LAME MP3 encoder in VBR at -V3 or better will almost definitely be indistinguishable from the original CD, so no.
Quote
I may re-download and transcode some, or all of it, or I may just leave them as-is.  (In MP3)  I'm just not sure yet.
If the MP3 encodings have been made properly then, as I said above, you are incredibly unlikely to be able to tell them apart from the original CD. As has been said to you numerous times in this thread already, transcoding them WILL hurt the quality. Transcoding just for the sake of it makes no sense whatsoever.

You've asked plenty of questions and been given almost unanimously agreed answers. Please try listening to what people are trying to tell you.

Cheers, Slipstreem.