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Topic: (AAC) advantages & disadvantages (Read 53205 times) previous topic - next topic
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(AAC) advantages & disadvantages

What are the advantages and disadvantages of using AAC over MP3? Other than hardware support.

Wiki: (AAC) Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at many bit rates.

I know Lame MP3 at lower bitrates is hard to compare to when it comes to VBR quality.

(AAC) advantages & disadvantages

Reply #1 –
AAC is a little newer and codes a lot better for very low bitrates.  At higher bit rates (192k) theres not much difference other then hardware support.

I would use AAC if you need 128k or lower and don't mind reduced hardware support.  Otherwise MP3 is nice due to universal compatibility.

(AAC) advantages & disadvantages

Reply #2 –
So the higher bitrates in AAC wouldn't be as good as the higher bitrates in MP3?

(AAC) advantages & disadvantages

Reply #3 –
it's true that mp3 decoder is lets resource intensive ??
this can save some battery life

(AAC) advantages & disadvantages

Reply #4 –
Quote from: Manu on
So the higher bitrates in AAC wouldn't be as good as the higher bitrates in MP3?


No. They are excellent. There is not much difference between MP3 and AAC, both perform equally well. There are many listening test, you might try to examine some of them and see the results.

(AAC) advantages & disadvantages

Reply #5 –
Quote from: arthurprs on
it's true that mp3 decoder is lets resource intensive ??
this can save some battery life


Depends on the device.  Generally everything has a well optimized MP3 decoder since its the standard.  Many devices have less well optimized codecs for other formats.  However on some devices (ipods) AAC is just as fast decoding as MP3.

(AAC) advantages & disadvantages

Reply #6 –
According to this Wikipedia entry:

http://en.wikipedia.org/wiki/Advanced_Audio_Coding


Quote
AAC's improvements over MP3


AAC was designed to improve on the MP3 format (which was specified in MPEG-1 and MPEG-2) by the ISO/IEC in 11172-3 and 13818-3.

Advanced Audio Coding is designed to be the successor of the MP3 format and demonstrates greater sound quality and transparency than MP3 files coded at the same bit rate[citation needed].

Improvements include:

More sample frequencies (from 8 kHz to 96 kHz) than MP3 (16 kHz to 48 kHz)

Up to 48 channels (MP3 supports up to two channels in MPEG-1 mode and up to 5.1 channels in MPEG-2 mode)

Arbitrary bit-rates and variable frame length. Standardized constant bit rate with bit reservoir.

Higher efficiency and simpler filterbank (rather than MP3's hybrid coding, AAC uses a pure MDCT)

Higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 samples, allowing more efficient coding than MP3's 576 sample blocks)

Higher coding accuracy for transient signals (AAC uses a blocksize of 128 samples, allowing more accurate coding than MP3's 192 sample blocks)

Can use Kaiser-Bessel derived window function to eliminate spectral leakage at the expense of widening the main lobe

Much better handling of audio frequencies above 16 kHz

More flexible joint stereo (different methods can be used in different frequency ranges)

Adds additional modules (tools) to increase compression efficiency: TNS, Backwards Prediction, PNS etc... These modules can be combined to constitute different encoding profiles.


(AAC) advantages & disadvantages

Reply #7 –
The AAC specification was written with mp3's known design-limitations in mind and it has new technologies that solve some problems of mp3. But mp3 is older and encoders like LAME have been fine tuned over the years to a degree where many of these issues were circumvented (at least with high bitrate files). For high bitrate files, the difference is negliable because mp3 is very optimized but AAC, although having better technological conditions, isn't as mature yet. Even when it gets better tuned, you can't get any better then transparent, so AACs strenght lies in lower bitrate regions.
But at low bitrates (<128 kbps) AAC is definitely better then mp3. Mp3's limitations come into effect here since there isn't enough bitrate to encode around them.

(AAC) advantages & disadvantages

Reply #8 –
At the end of the day it comes down to what bitrate you use for your music.  At high bitrates say 160kbps and up MP3 performs just fine compared to AAC and you also gain compatibility. Where at low bitrates 128kbps and lower AAC really pulls ahead of MP3.  Oh and compatibility with AAC isn't much of an issue these days anyway, even Microsoft is now supporting AAC.  Still there's nothing stopping you from using both.

(AAC) advantages & disadvantages

Reply #9 –
Quote from: Manu on
What are the advantages and disadvantages of using AAC over MP3? Other than hardware support.

Wiki: (AAC) Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at many bit rates.

I know Lame MP3 at lower bitrates is hard to compare to when it comes to VBR quality.


AAC is a newer generation of lossy audio codec than MP3.
So, it is more advanced in audio coding compared to mp3.
The AAC format has more sample frequencies, and it is much efficient in encoding (from the aspect of filterbank, stationary and transient signals etc....)

Going to sound quality.....
At 64kbps, HE-AAC sounds almost as good as MP3 at vbr -v5
(well, to my ears.... I have a hard time distinguishing them  )
while Mp3 at 64kbps doesn't sound good. Even at 48kbps (HE-AAC), the sound quality is still acceptable.
I'm using AAC vbr quality 0.55 (about 200kbps average) on my nokia phone and sony walkman and they sounded really, really good.... 

I'm not sure about the disadvantages of AAC (maybe a little bit slower encoding speed compared to lame 3.98..)

anyway... you should explore yourself to know how good is aac codec compared to mp3...
try encoding some samples at diffrent bitrate/setting and compare them to mp3...

(AAC) advantages & disadvantages

Reply #10 –
I can think of some disadvantages of AAC, they mainly focus around compatibility.  AAC software and hardware compatibility has increased over the years thanks to the success of iTunes and iPods.  However, you still have to be careful which portable player you purchase.  The SanDisk Sansa line does not support AAC audio (their top end player does but the rest don't).  Even then, AAC support can still be buggy.  The Creative Zen was having issues with Nero AAC files for some odd reason.  It was fixed when Nero came out with their new AAC encoder.  Creative didn't do anything to solve the problem, Nero did.  Additionally, many factory installed car CD decks still support only mp3 and WMA files.  Some of them support AAC but only through the use of USB media.  Another disadvantage is the lack of a unified tagging structure.  mp3 has ID3 tag, there are different versions of it (v1.1, 2.2, 2.3, 2.4, etc.) but they are still standards.  The AAC community never came up with a standard and there was a time when everyone used their own technology.  The growth of the iPod and iTunes has made Apple's tagging setup become the unofficial standard.  However, there are still some devices that don't support Apple's AAC tagging structure.  The PS3 is one big one.  I have to use software (TVersity) that will automatically convert the tags on-the-fly as it copies them over to my console.

I use Nero's AAC encoder as I have an iPod, Xbox 360, PS3, Wii, and an iPod integration kit in my Honda Civic.  I can play my AAC files anywhere I want.  However, I had to spend $70 for this iPod kit as my factory stereo would playback audio/mp3/WMA CDs only.  You just have to be aware that you may come across some device that doesn't work with AAC files or the tagging system that they use.  Also, as others have said, most modern day lossy encoders begin sounding alike at high bitrates.  AAC may have all these advantages on paper but the Lame mp3 encoder has really pushed the mp3 format beyond what many thought it was capable of.  Past listening tests have shown that it can really compete with both the iTunes and Nero AAC encoders even at lower bitrate settings (128kbps VBR).

I went with Nero AAC because it was able to provide transparent results for me at -q0.45 (but I use -q0.50 as it resulted in around a 0.2MB increase per file).  I think that Lame does a very good job at -V 3 but I was still able to ABX some songs from that setting meaning that I had to go higher.  Even at -V 2, there were still some songs (mainly from Nine Inch Nails and Marilyn Manson) that I could ABX.  So, for me, I went with Nero because it could provide completely transparent results at -q0.45.  Even with the use of -q0.50, the file sizes were smaller than with -V 2 and Lame (about 1-2MB smaller per file).

(AAC) advantages & disadvantages

Reply #11 –
In addition to what Kornchild is saying, there are very few standalone DVD players can play AAC files.

I see MP3 support in almost all of them and WMA supported in many of them, but I can't recall seeing any that support AAC files.  I'm sure one or two exist, I just don't know of the brand/model.

So, while one can burn a CD-R full of 100 or so MP3 or WMA files and the standalone DVD player will play them, you can't do the same with AAC.

(AAC) advantages & disadvantages

Reply #12 –
Parity at higher bitrates is not true. Especially the following features have enabled AAC to handle hard to encode content much better than MP3 will ever be able to.

  • Higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 samples, allowing more efficient coding than MP3's 576 sample blocks)
  • Higher coding accuracy for transient signals (AAC uses a blocksize of 128 samples, allowing more accurate coding than MP3's 192 sample blocks)


Well, actually the first just enables it to be more efficient, but the second can really help with complicated material.

As good as LAME has become over the years, it can't surpass the format's inherent limitations. Many bad experiences with MP3 have been fixed in the AAC specification.

Just compare the number of known killer samples. It is several times higher for MP3 than AAC. Look at how the Nero devs were able to eliminate one killer sample after another. Many LAME killer sample's could not be fixed sufficiently for years. The format just isn't flexible enough.

  • Much better handling of audio frequencies above 16 kHz

Most people can't hear frequencies over 16-17 kHz. If you can, AAC will be able to handle this content much more easily.

Add AAC's native VBR support instead of a hacked implementation in the case of MP3, where still many players choke although being 100% spec conforming.

(AAC) advantages & disadvantages

Reply #13 –
Quote from: rpp3po on
Parity at higher bitrates is not true. Especially the following features have enabled AAC to handle hard to encode content much better than MP3 will ever be able to.

  • Higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 samples, allowing more efficient coding than MP3's 576 sample blocks)
  • Higher coding accuracy for transient signals (AAC uses a blocksize of 128 samples, allowing more accurate coding than MP3's 192 sample blocks)


]


Efficiency only matters at low bitrates.  At higher bitrates its irrelevant since theres too many bits anyway. 

Quote from: rpp3po on
Just compare the number of known killer samples. It is several times higher for MP3 than AAC.


Yes but theres an order of magnitude more MP3 users, so no surprise that theres more problem samples.  If AAC ever becomes popular like MP3, then people will find a lot more samples.

Quote from: rpp3po on
Add AAC's native VBR support instead of a hacked implementation in the case of MP3, where still many players choke although being 100% spec conforming.


This is false.  VBR support is native to MP3 and AAC.

(and broken VBR support is hardly a problem unique to MP3, I had my iPod for ages before it could decode VBR AAC files without randomly skipping ahead)

(AAC) advantages & disadvantages

Reply #14 –
Advantages:

Better precho handling.
Supports higher freqs.
Supports higher bitrates.
Outperforms Mp3 at any bitrate.
No sfb21 bloat.
Better track seeking.
ISO standard.

Disavantages:

Limited (but growing) support.
Poor decoder support i.e Creative.
Comes in many flavours LC, HE, LD etc.
Patented to the teeth.
Not many well tuned command lined AAC encoders.
iTunes M4A vs MP4 file extention.
Getting gapless playback to work under Linux.

-
I have been using AAC at 200kbps VBR for a while now for my iPod, which offers me better sound and most of time produces smaller files then my old LAME V2 encodes. Most of the time LAME V3 and V2 is transparent to me, but i found too many problems such as drum smearing and i can ABX quite a few songs from Ministry, Metallica and Skinny Puppy. While i only have a few problem tracks with Nero at 0.55.
"I never thought I'd see this much candy in one mission!"

(AAC) advantages & disadvantages

Reply #15 –
Quote from: Mike Giacomelli on
Efficiency only matters at low bitrates.  At higher bitrates its irrelevant since theres too many bits anyway.


Higher transient resolution is an accuracy and not an efficiency feature.

Quote from: Mike Giacomelli on
Yes but theres an order of magnitude more MP3 users, so no surprise that theres more problem samples.  If AAC ever becomes popular like MP3, then people will find a lot more samples.

  • The biggest lossy music retailer worldwide is Apple.*
  • For years, most AAC killer samples could be fixed. MP3's couldn't. Use the search function.
  • Problem samples usually don't just pop out of the mass but are actively researched at communities like Hydrogenaudio. Actually we have had even more activity regarding AAC samples in the last years. Still the number of unfixed MP3 samples is higher.


So as much as you utterly want MP3 to be better in this regard, it just isn't. The MP3 spec was finalized in a kind of rush. A lot of stuff has been fixed or done better in its successor.

Quote from: Mike Giacomelli on
This is false.  VBR support is native to MP3 and AAC.


Read the spec before making false claims. VBR support has never been officially included for MP3. A MPEG compliant hardware decoder does not have to support it. It is a feature later added by codec developers, not by its standardization committee. MP3 has originally been designed around constant bitrates.

Quote from: rpp3po on
(and broken VBR support is hardly a problem unique to MP3, I had my iPod for ages before it could decode VBR AAC files without randomly skipping ahead)


I don't know what crappy encoder you have used. I have never had a problem like this. AAC has a variable bitrate design from the ground up. CBR and ABR are actually constraints to its basic operation.** In the case of MP3 it's the opposite, VBR is an arbitrary pseudo standard extension to the original spec. If a player manufacturer wants to support MP3 VBR encodes there is enough information out there to implement it, but he won't find it in the official specification.


* As of January 2009, the store has sold 6 billion songs, accounting for more than 70% of worldwide online digital music sales.
** Probably because codec developers had the most experience with CBR codecs like MP3, early AAC encoders were also mainly ABR/CBR implementations.

(AAC) advantages & disadvantages

Reply #16 –
Quote from: /mnt on
Patented to the teeth.


Licensing for AAC is AFAIK pretty straight. It's all handled by a single institution and fees are capped. Isn't that even more complicated and costly for MP3?

Quote from: /mnt on
Not many well tuned command lined AAC encoders.


Well, we have Nero on Windows, Linux, and Mac (through Wine). Its quality is beyond doubt. On the Mac there is additionally afconvert on the command line and a nice CoreAudio API. Its quality is also excellent. Quality-wise I'm not missing anything. OK, a open source product in the same quality league would be nice.

(AAC) advantages & disadvantages

Reply #17 –
Quote from: rpp3po on
Well, we have Nero on Windows, Linux, and Mac (through Wine). Its quality is beyond doubt. On the Mac there is additionally afconvert on the command line and a nice CoreAudio API. Its quality is also excellent. Quality-wise I'm missing nothing. OK, a open source product in the same quality league would be nice.


It's just if you want to use EAC or foobar2000, your stuck with only FAAC or Nero AAC, which is good encoder btw. Also a new open source AAC encoder to replace FAAC would be awesome, am getting sick of being stuck with FAAC when i rip DVDs with Handbrake.
"I never thought I'd see this much candy in one mission!"

(AAC) advantages & disadvantages

Reply #18 –
Quote from: rpp3po on
The biggest lossy music retailer worldwide is Apple.


Relevance? 

Quote from: rpp3po on
For years, most AAC killer samples could be fixed. MP3's couldn't. Use the search function.
Problem samples usually don't just pop out of the mass but are actively researched at communities like Hydrogenaudio. Actually we have had even more activity regarding AAC samples in the last years. Still the number of unfixed MP3 samples is higher.


MP3 has been used by far more HA members and for far longer.  The well known MP3 problem samples date back the better part of a decade.  HA members prefer it by a factor of several:

http://www.hydrogenaudio.org/forums/index....showtopic=68338

Integrate the area under the MP3 and AAC curves:

http://img206.imageshack.us/img206/3774/ha1fg1.png

And tell me which you think has had more careful listening for longer.  You're so focused on the numerator that you're forgetting the importance of the dominator when calculating a ratio and have come to an unsupportable conclusion.  Retract it. 

Quote from: rpp3po on
So as much as you utterly want MP3 to be better in this regard, it just isn't.


Been posting here about using AAC since before you were an HA member, noob.

Quote from: rpp3po on
Quote from: Mike Giacomelli on
This is false.  VBR support is native to MP3 and AAC.


Read the spec before making false claims. VBR support has never been officially included for MP3. A MPEG compliant hardware decoder does not have to support it.


I do not believe this is correct.  Quote this from the specification to me.

Quote from: rpp3po on
(
I don't know what crappy encoder you have used.


Ahead Nero.  The problem is well documented in these forums.  And since I'm not so lazy to tell you to search, I'll even provide a link:

http://www.hydrogenaudio.org/forums/index....showtopic=17773

Quote from: rpp3po on
I never had a problem like this.


I've never had a VBR MP3 problem.

(AAC) advantages & disadvantages

Reply #19 –
Quote from: Mike Giacomelli on
Relevance?


I thought you may have underestimated the number of circulating AAC tracks on this planet.

Quote from: Mike Giacomelli on
The well known MP3 problem samples date back the better part of a decade.


Well, a decade time to fix them. The Ahead devs, and I don't think LAME devs are less capable, are usually able to fix such issues in less than a year. Do you still want to neglect this to be an indication that MP3 has just more inherent (and actually relevant) limitations? The same decade that you cite with respect and its problem samples didn't just help MP3 to mature, but have also influenced the AAC spec.

AAC is not a competing format, but MP3's official successor and was partly developed by the same scientists and institutions as MP3. Much of the experience made with MP3 went right into AAC. So its not maturity vs. the new kid on the block. I'm pretty confident that there will never be as many outstanding problems with AAC as there are with MP3, especially regarding pre-echo and high frequencies. The latter has always been kind of a mess for MP3. The official bitstreams for decoder compliance tests even exclude the matter completely.

Quote from: Mike Giacomelli on
Quote from: rpp3po on

Read the spec before making false claims. VBR support has never been officially included for MP3. A MPEG compliant hardware decoder does not have to support it.


I do not believe this is correct.  Quote this from the specification to me.


I can't. The spec only defines the bitrates 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 192, 224, 256 and 320 kbit/s. No mention of VBR.

(AAC) advantages & disadvantages

Reply #20 –
Quote from: rpp3po on
Quote from: Mike Giacomelli on
Relevance?


I thought you may have underestimated the number of circulating AAC tracks on this planet.


Very well.  Then what is the relevance of me underestimating the number of circulating AAC tracks on this planet?  I fail to see the connection to your argument.

Quote from: rpp3po on
Quote from: Mike Giacomelli on
The well known MP3 problem samples date back the better part of a decade.


Well, a decade time to fix them. The Ahead devs, and I don't think LAME devs are less capable, are usually able to fix it in less than a year. Do you still want to neglect this to be an indication that MP3 has just more relevant inherent limitations?


I do.  It is a vague and unsubstantiated generalization of an opinion you hold.  It indicates nothing beyond the fact that you disagree with me, a fact I am already aware of.

Quote from: rpp3po on
The same decade that you cite with respect and its problem samples helped to improve the AAC spec.


For what its worth, this is wrong.  AAC-LC had already been more or less finalized by then, which is what you seem to be referring to above.

Quote from: rpp3po on
Quote from: Mike Giacomelli on
And tell me which you think has had more careful listening for longer.  You're so focused on the numerator that you're forgetting the importance of the dominator when calculating a ratio and have come to an unsupportable conclusion.  Retract it.


Since AAC is not a competing format, but MP3's official successor and was actually partly developed by the same people as MP3, I think a lot of the experience made with MP3 went right into AAC. So its not maturity vs. the new kid on the block.


Since this doesn't appear to refute or even address the numerical counter-evidence I have provided to show that you are wrong, I will take this as a tactless retraction of your above argument that somehow ratios can be evaluated independently and without knowing their denominators and move on.  If you think some part of what I have quoted is an argument in and of itself, feel free to pursue it further.

Quote from: rpp3po on
Quote from: Mike Giacomelli on
Quote from: rpp3po on

Read the spec before making false claims. VBR support has never been officially included for MP3. A MPEG compliant hardware decoder does not have to support it.


I do not believe this is correct.  Quote this from the specification to me.


I can't.


So much for "Read the spec before making false claims".  I suppose "trust me because I'm pretty sure I'm right and can't be bothered to check" just didn't sound as clever.

(AAC) advantages & disadvantages

Reply #21 –
Well, I guess you didn't get that I can't because it's not in there. ISO/IEC 11172-3:1993 does not mention VBR. Only the bitrates, that I have cited.

What you claim is wrong and I can't cite what's not there. Ask some LAME devs if you don't believe it.

(AAC) advantages & disadvantages

Reply #22 –
Quote from: rpp3po on
Well, I guess you didn't get that I can't because it's not in there. ISO/IEC 11172-3:1993 does not mention VBR. Only the bitrates, that I have cited.


Looking at the compliance vectors, some are VBR, so unless I am completely mistaken, you appear to be wrong.  Feel free to double check:

he_44khz.bit    all bitrates at 44,1 kHz (padding included)
[...]

Frame  Action
---------------------------------------------------------------------------

  1-10  bitrate = 32 kbit
 
11-20  bitrate = 40 kbit 
                           
21-30  bitrate = 48 kbit 

[...]

A simple google search reveals dozens of links confirming what the specification says.

Taken from ISO 11172 with a modified date in 1994. 

Quote from: rpp3po on
What you claim is wrong and I can't cite what's not there. Ask some LAME devs if you don't believe it.


Amazing.

(AAC) advantages & disadvantages

Reply #23 –
Quote from: Mike Giacomelli on
Since this doesn't appear to refute or even address the numerical counter-evidence I have provided to show that you are wrong,..


By numerical counter-evidence you mean the hydrogenaudio user polls, that are supposed to support your argument that 6 years of additional development basically don't have improved AAC over MP3??  I regret trying to convince you in the first place. So please bear with me if I don't follow every thread of your argument. Even if some of them may be consistent in themselves, I can't take the basic claim that they shall support serious.

AAC was a considerable improvement over MP3. Ask LAME developers about their headaches with high frequency encoding (sfb21 anybody) and AAC developers why they didn't share them. Look at why so many pre echo problems couldn't be eliminated for MP3, but could for AAC. The AAC spec was improved significantly over MP3. That's the data from my point of view and I consider the rest is rhetoric to defend a questionable thesis.

The ISO example you cite, shows perfectly why spec compliant MP3 is basically fixed bitrate oriented in a crude way. You can only switch betwen bitrates 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 192, 224, 256 and 320 kbit/s back and forth, but can't just exactly allocate as much bytes to a frame as you need. That's not VBR but VFBR, variable fixed bitrates.

If you want to see it done right, look at AAC. For every frame there can be allocated as many bytes as needed. No need to switch between a set of fixed rates. There's also generally less interdependency between frames, which makes it a lot easier for true VBR.

Finally, what's an MPEG spec compliant VBR header for a mp3 file? Why is there a Xing, LAME, and FhG flavor when it is part of the spec as you claim?

(AAC) advantages & disadvantages

Reply #24 –
Quote from: Mike Giacomelli on
Been posting here about using AAC since before you were an HA member, noob.


That's also not true, btw...  Before I had become a member at HA you never had even mentioned AAC. The first time you commented on it was five days later. And doesn't that look that familiar?  Even back then you were already trying to convince people to just stick with MP3 (instead of answering the original question wether there were portable players that supported AAC):

Quote from: Mike Giacomelli on
Quote
With hard drives for PC's so cheap these days I'm not all that concerned about file size, I figure using a bit rate of 256 kbps all the lossy codecs should sound good. Or is this a bad assumption?


Then why not use MP3?  Its more compatable and you yourself just said everything sounds good to you at high bit rates.

Quote
I know just about every portable out there supports mp3, but what about the other formats. Ogg really appeals to me as it's open source, but in the end I want portable support.


Since LAME is also open sourced and works with ever portable MP3 player, I'd probably use that.  Not to mention it works nicely with ipods.


So we could have had exactly the same discussion already six years ago. Back then I was already highly impressed with Dolby's AAC encoder implemenation in MusicMatch Jukebox, but I hated the program's shiny plastic interface and there was no alternative, so I rarely used it until Nero became available.