Clarification of MPEG 4, AAC and Apple

[MacRumors]

Based on posts/responses on the forums, it appears there is still a significant amount of confusion regarding audio codecs and their implications.

For clarification purposes, "MP3" is officially known as MPEG-1 Layer 3. This audio codec provides the popular compression format that both iTunes and the iPod support.

Songs can be encoded at varying "bitrates". The most common bitrate for MP3 is probably "128kbps". This translates into 128 kilobits per second -- which means the format will use 128kilobits of data to encode one second of audio - no more, no less. Therefore, the final size of a file depends on both Bitrate and the Length of the Song.

Many users, however, prefer to utilize larger bitrates to achieve higher quality audio, but at the sacrifice of a larger final file size. Based on this popularly referenced c't magazine blinded study (http://www.geocities.com/altbinariessoundsmusicclassical/mp3test.html), it is commonly held that 256kbps MP3 are equivalent to original CD Audio:

In plain language, this means that our musically trained test listeners could reliably distinguish the poorer quality MP3s at 128 kbps quite accurately from either of the other higher-quality samples. But when deciding between 256 kbps encoded MP3s and the original CD, no difference could be determined, on average, for all the pieces. The testers took the 256 kbps samples for the CD just as often as they took the original CD samples themselves.

AAC/MPEG4

This page at Apple (http://www.apple.com/mpeg4/aac/) helps clarify some terms and definitions regarding the audio format: AAC. Advanced Audio Coding (AAC) is the audio codec for the standard known as MPEG-4. According to Apple's site, AAC provides advantages over MP3 -- but the most significant for end-users is the improved compression algorithm:

AAC compressed audio at 128 kbps (stereo) has been judged by expert listeners to be "indistinguishable" from the original uncompressed audio source.*

As a result, the advantage of AAC will be better quality audio at the same file sizes. Or, alternatively, equal or better quality at smaller sizes.

Some commonly asked questions:

Q: Is a 128kbps AAC/MPEG4 file smaller than a 128kbps MP3?
A: No. They are exactly the same size... but the AAC file should sound better. See above.

Q: Will there be a way to convert my MP3's to AAC files?
A: Converting directly from MP3 to AAC is not recommended (by this author). Going from a 128kbps MP3 to a 128kbps AAC file will provide no space spavings, and yet you will likely lose audio quality. (both are "lossy" file formats). Remember, you will never "regain" the quality lost when a song was encoded into MP3. The recommended course of action would be to re-rip the files from its original format (CD, for example).

[Abstract]

Bah, I hate it when they say that 256kbs is the same quality as an Audio CD. That's bull. I encode at 320 kbs and that sounds fine, but the bass is the weakest part of mp3 encoding. There are much better formats out there that are almost lossless quality.

Is this AAC going to be better than "almost lossless", because I sure can't see anything compressed as being completely lossless.

[ldjessee]

Thanks for taking the time to help people understand.

[grapeice]

Thank you for finally laying this all out. I know I heard this all, but I tend to forget, and I think others did too. It'll be interesting to see what Apple really goes with on this Music Subscription Service, if indeed that really rolls out too. :)

[mattalici]

I love that MacRumors takes the time to spell this stuff out for the little people. It took me like 5 years to figure out what mobo meant. (motherboard) I thought it was an insult.

Team MacRumors rules!

[Steamboatwillie]

As far as MP3s that is...

Encoding with different encoders, with different settings, yeilds different results. My favorite is LAME set with the --r3mix options. These files sound excellent and are close to most 128kbs file sizes. I encourage anyone interested to go to http://r3mix.net/ and read about it. My point is: not all MP3 files can be judged for quality based on just the bitrate. Also, unless the file sizes are reduced dramatically, I see no need for new codecs. I have an in dash MP3/CD player in my car and I'de like to get a few years out of it before I feel compelled to upgrade to whatever is new and better. I feel MP3 still has a lot of life left in it.

[Steamboatwillie]

Originally posted by Abstract
I encode at 320 kbs and that sounds fine

Try LAME --r3mix and save a bunch of disk space.

[arn]

Originally posted by Abstract

Is this AAC going to be better than "almost lossless", because I sure can't see anything compressed as being completely lossless.

of course there are lossless compressions out there... there are a few audio ones (shorten, is on that comes to mind), along with all the usual compressions - zip, stuffit, gz, lzw.... those are all lossless.

AAC is lossy, of course... I don't know which formats you are talking about (almost lossless)

arn

[Sheebahawk]

Can an ipod/itunes play mpeg4's as it is right now? if not I should probably wait until it does before buying one... I plan on using it in my car and I like my bass loud and clear...

would it be just as easy to start using mpeg4 as the standard audio format for apple's music solutions? like ripping cd's into mp4 on the next version of itunes? Calling it mp4's (unless mp4 is already taken by mpeg-1 layer 4 or something) would definately make the masses think that it is superiour to mp3's, and using it as the standard in apple's music service would just provide yet another advantage over gnuetella and any competing solutions.

Now I'm getting worried that i'll have to pay for the thousand songs I've already "borrowed", just to get the mpeg4 versions, so they sound better. I've already put all my cd's into storage/given them away/sold them after ripping them into mp3...

Mpeg-4's descriotion sounds good though, I hope apple pushes it as the new standard, as I've always worried about my mp3's sounding inferior to people who still use CD's.

[evilbert420]

"Going from a 128kbps MP3 to a 128kbps AAC file will provide no space spavings, and yet you will likely lose audio quality."

Okay, but if all my MP3s are 320kbps, then that might be acceptable to convert to a 128kbps AAC, no?

I grimace to think about having to re-rip another 15gigs worth of albums. I assume it's only a matter of time before a conversion mechanism is available, unless AAC has some copy-protection embedded that would prohibit this.

When answering a question, it's okay to give your opinion... but you didn't answer the question of whether it can be done.

[arn]

Originally posted by evilbert420
Okay, but if all my MP3s are 320kbps, then that might be acceptable to convert to a 128kbps AAC, no?

When answering a question, it's okay to give your opinion... but you didn't answer the question of whether it can be done.

The question becomes - why do you want to convert to AAC? Why do you want to convert your 320kbps MP3 to 128kpbs AAC?

It won't sound better... if anything, it'll sound worse.
It will take up less space... but drive space is cheap.

If you have an AAC-only playing device - that might be the most legitimate reason to do so.

As for "is it possible" - yes, it's possible. Right now, you'd have to convert to AIFF (noncompressed format first) and then convert that to AAC.

arn

[ennerseed]

just some personal thoughts...

I would keep you mp3s as they are.

i would re-rip your cds to aac... this time make sure it sounds good to you!

I have thousands ( 4221 ) of mp3s, I could re-rip but they are from vinyl and are a pain in the a** to record, much less tag properly. I have totally stoped recording my records till I find out what the final deal is with aac, iTunes, iPod.

As time went on I went from 128k to 320k and really wish this stuff came, would be coming, about faster.

Thanks for the info Arn

[Tom800]

Is it possible that iTunes 4 will have the LAME encoder or a similarly top-quality encoder at its heart? I've heard the current iTunes encoder is decent and fast, but compromises on quality... Could there be an option to toggle between encoders?

[arn]

Originally posted by Tom800
Is it possible that iTunes 4 will have the LAME encoder or a similarly top-quality encoder at its heart? I've heard the current iTunes encoder is decent and fast, but compromises on quality... Could there be an option to toggle between encoders?

you can use iTunes-Lame Encoder (http://www.versiontracker.com/dyn/moreinfo/macosx/13048) in the meanwhile

arn

[redAPPLE]

Originally posted by Abstract
Bah, I hate it when they say that 256kbs is the same quality as an Audio CD. That's bull. I encode at 320 kbs and that sounds fine, but the bass is the weakest part of mp3 encoding. There are much better formats out there that are almost lossless quality.

Is this AAC going to be better than "almost lossless", because I sure can't see anything compressed as being completely lossless.

i agree. compressing any file, would result to quality loss.

[bignumbers]

Has anyone independently done a real comparison of MP3 vs AAC? Apple claims AAC is better, but (as much as I do like Apple) they are of course biased towards their own products.

And you probably can't even do a direct comparison of MP3 vs AAC, because there are a multitude of encoders. If Apple is comparing a great AAC to their adequate (but not great) MP3, is that a valid comparison?

I agree that a conversion to something other than MP3 will be a tough sell. Many consumer CD players now play MP3 CD's. What will happen if you have a library of AAC's and want to make an MP3 CD? Could you? Would you need to convert everything? At what loss of time and quality?

And would there be a way to maintain mirror libraries of different formats? I'd like that now. I like high-quality MP3's for listening at home through good speakers. But when I'm mowing the lawn, do I really need 256K+? I have two MP3 players, a 5GB iPod and a 64MB Nomad IIMG; how about loading the Nomad with 64K music so I can store more than 45 minutes?

Oh, the confusion...

[centauratlas]

>The question becomes - why do you want to convert to AAC? Why do you want to convert your 320kbps MP3 to 128kpbs AAC?<

For me, I would convert from 320kbps to some-kbps AAC for a couple of reasons:
1. If I can get the same quality at say 240kbps AAC as 320kbps MP3, then that gets more room on the iPod
2. It saves some room on the hard drive and gets the same quality.

Admittedly if Apple made a 50GB (or larger) iPod I would just record at the best quality bit-rate with the best quality encoder. But they don't yet do so.

Ideally what I would like it to have 7000 songs scanned in at the best quality available (320kbps MP3 when I did my scanning), and have iTunes have an option to send a 160 kbps (or something) version to my iPod. Then when i got a bigger iPod I would up the quality being synched to it.

Alternatively, I'd like something like the Rendezvous enabled iTunes with a tablet and speakers on the tablet. Then I'd have all my tunes available anywhere the tablet was in the house.

>It will take up less space... but drive space is cheap.

Except when you absolutely can NOT get more space on the iPod... ;-)

[bikertwin]

And remember that using VBR (variable bit rate), even iTunes' MP3 encoder does a good job at 160 kbps. Takes a little longer to encode, but it's worth it for the quality. MP3's tinny sound at 128 kbps drives me batty, but I still need to keep the file size down since my Sony Clie only holds a 128 MB memory stick.

[fantomas1976]

r3mix is a good lame setting but dibrom's newer tuned --alt-preset's are the top quality mp3 settings you can use in LAME, and are tuned much better for transparent quality. Here is a link with the presets you can check out http://www.hydrogenaudio.org/index.php?act=ST&f=15&t=203&st=0

[mangoduck]

for those of you asking about mp3 to aac conversion, i really see no point.

lets say you have a jpeg file that you want to convert to some newer and more efficient jpeg compression algorithm. in photoshop, or graphics program of choice, open the file and save as / save for web and select jpeg. even though the new version of the format is better overall, your final product should look even worse than before. not only do you not magically regain image quality simply by opening the file in an image editor, but you also compress the artifacts that resulted from the FIRST compression.

i use this example because (i think, correct me if i'm wrong) mp3 audio compression uses the same principle as jpeg, and later, mpeg. i swear if you could listen to a jpeg, it would sound like an mp3.

so in short, you don't really gain anything from this conversion. stick with your existing mp3s, and just use aac for new rips from the source.

[kwajo.com]

Originally posted by bignumbers
Has anyone independently done a real comparison of MP3 vs AAC? Apple claims AAC is better, but (as much as I do like Apple) they are of course biased towards their own products.


I have ripped many of my most treasured CDs in mp4 through Quicktime and they are mixed in my iTunes library along with everything else (mp3s, wavs, aiffs). honestly, they do sound improved, and, just as with mp3, the higher the bitrate, the better. I have experimented with mp3-to-mp4 and it is not worth it, the quality does go down, so don't even think about it. the mp4s (despite what Apple says) do use more CPU, but that will probably improve as they become more integrated. don't listen to people who say that mp4s at half the bitrate of mp3 sound the same; that is garbage. 64 kbps mp4s do not sound the same as 128kbps mp3s, though they are miles ahead of their mp3 counterpart. I use either 160 or 192 as the bitrate for my mp4s, and for me tht yeilds good results (if I want full quality, I make the effort to go grab the CD off the shelf).

so in the end they do sound better, and once iTunes makes it easier to rip them and plays back a bit more smoothly, I would recommend re-ripping as many of your CDs as you have the patience to do.

p.s. It is true that telling people that you have a beatles collection ripped in 'mp4' sounds impressive, higher numbers make people believe it is better no matter what

[impierced]

Originally posted by Steamboatwillie
Try LAME --r3mix and save a bunch of disk space.

The "--r3mix" has been superseded by the "archive quality" "--alt-preset standard" for lame encoding.

--r3mix will be a bit smaller at good quality, but the --alt-preset standard will sound much better.

Do a blind test on your hi-fi system and I think you'll agree.

[bennetsaysargh]

ok everyone. do a blind test and see for yourself which is the higher quality. a 192kbps mp3, or a 96 kbps mp4. i'm about to do mine now. i'll report back with my results later.

[bennetsaysargh]

i just did a blind test, and mixed the 1st half and second half of a song. (1st half in mp3 and the 2nd in mp4. also done visa versa).
my results. they both sounded the exact same quality. the mp3 file was 5.5mb, while the mp4 was only 2.8mb. i'll stick with the mp4.

[Abstract]

That's not much of a blind test. :p


I wouldn't touch a thing. Its not as if this is an issue for me right now. It wouldn't be difficult to re-rip an album, but since I have everything at 320kbs, why would I want to switch over to mp4? To save HD space? I have plenty of space because i don't carry too many mp3's. When I don't like an mp3, or if I know I'll never listen to it ever again, I delete it. What would I do with 11 GB of mp3's, maybe show off my large collection? I have only what I know I may listen to. If you have enough HD space, then don't switch. Just because a new technology comes out, it doesn't mean that you need to make an issue out of nothing. If music quality wasn't a problem before, then don't switch for the point of switching. My music sounds great the way it is. ;)

[elo]

Two thoughts:

1. For those who have plenty of space and want maximum quality, you can *already* rip your CD's using the lossless AIFF format in iTunes.

2. Listening improves through education (this is my job). Those who don't hear a difference between two songs encoded differently may well learn to reliably hear a difference if shown how to listen and what to listen for. This can be proven using double-blind tests. If you *don't* hear a difference, it doesn't necessarily mean that a difference isn't audible to others.

Nice thread.

elo

[docpsycho]

This is all fine and dandy . . . But I will treat all compression techniques and a digital version of cassette.

I am NOt a musician. or have perfect pitch trained ears yet I can tell:

1: all forms of compression
2: all fox channels on dish and Directv are badly compressed
3: the difference between a one bit and a sixteen bit cd player
4: standard and HDCD encoded cd's

I guess this explains why I do most of my listening on SACD or DVD Audio. (by the way the rerelease of Pink Floyd's dark side of the moon is wicked)

For me to tell the diff' from all these formats was in 5 minutes in a high end audio shop. NOT BEST BUY(mostly low end stuff)

As a MAC user, I demand a higher level of quality, not quantity, in all of my purchases.

Yes most look at the price tag and understandably so, but I'll go without if the market provides a junk only option

'nuff said

[Snowy_River]

Originally posted by ennerseed
just some personal thoughts...

I would keep you mp3s as they are.

i would re-rip your cds to aac... this time make sure it sounds good to you!

I have thousands ( 4221 ) of mp3s, I could re-rip but they are from vinyl and are a pain in the a** to record, much less tag properly. I have totally stoped recording my records till I find out what the final deal is with aac, iTunes, iPod.

As time went on I went from 128k to 320k and really wish this stuff came, would be coming, about faster.

Thanks for the info Arn

Ah! So I'm not the only one who is converting an older music collection to a newer format. Here's a piece of advice: You can keep on recording. Just record to AIFF, burn a CD, then convert to MP3 (or MP4). If, later, you want to re-rip the music, you have a copy on CD that iTunes will remember the tags for, and it was recorded from the lossless AIFF format (i.e. best quality possible). Of course, the down side of this is you have to buy lots of CD-Rs...

:D

[porovaara]

Originally posted by docpsycho
3: the difference between a one bit and a sixteen bit cd player


What does this sound like to you? (Honestly curious). For those who can't hear the difference between mp3s done at things like 128-196, etc... try the following:

Get the source CD. Pick out a specific percussion instrument or the strongest portion of the bass line. Listen to it. Now play the mp3 specifically listening for that portion only. You should notice a definite difference in crispness, strength and clarity. You can also do this with strong voice performances, try a piece of opera. But the best overall way I've found to demonstrate the difference between mp3 bit rates is classical music. mp3 at lower bit rates absolutely murders the full-bodied sound of an orchestra.

As to encodings everything I do or have done for the last bit has been lame+alt preset. The size growth is definitely worth the difference in quality. Another thing I rarely see people talk about is how mp3s sound coming from different hardware. Luckily the iPod is one of the better sounding portable mp3 players (although to my ears the pjb100 still sounds more full despite less output power).

[C14ru5]

Originally posted by docpsycho
This is all fine and dandy . . . But I will treat all compression techniques and a digital version of cassette.

I am NOt a musician. or have perfect pitch trained ears yet I can tell:

1: all forms of compression
2: all fox channels on dish and Directv are badly compressed
It seems to me like you are confusing BITRATE compression and DYNAMIC compression. The former does nothing of the latter as long as we're not talking about the kind of bitrate compression used in cellular phones. I apologize if your point in saying this was only to emphasize that you have good ears.
3: the difference between a one bit and a sixteen bit cd player
I believe you are referring to SACD vs. Red Book AudioCD. To clarify the issue: SACD uses a 1 bit PAM signal with 64 x oversampling to overcome the shortcomings of a 16 bit PCM signal (i.e Audio CD). The result is, presumably, alot better, but the SACD Sony/Phillips standard is not compatible with most of today's audio equipment.

On the other hand, if your point was to emphasize that you hear the difference in ENOBs (Effective Number Of Bits), then please answer the following: If you were to hear a stereo DVD Audio recording (24 bit) and a CD recording (16 bit) through THE SAME SIGNAL CHAIN, would you hear any difference? Chances are you would not. Why? If you were to buy the world's most expensive AD/DA converter, it would still only give you 17 ENOBs.

My third interpretation of your statement is that you are confusing quantize levels (bits) with throughput (bps, bits PER SECOND). They are in no way related especially since mp3 uses variable quantize levels (don't confuse with variable bit rate!), so any such comparison becomes irrellevant.

What's my reason for saying all this? Mainly that there is about as much confusion with bits in the audio world as with bits in the processor world - and we've all seen the big discussions on the 32 vs. 64 bit processor issue, right?

[Steak]

Not that I'm against a new format. but this story is a load of crap. Anyomne with even half an ear, can hear a vast difference between an MP3 at 256kb, and original CD file. cd's sound bad enough, Mp3, or Mp4, sounds bad. 256kb p/s doesnt help with MP3's harsh, mid-heavy crappy sound. An MP3 is like listening to a pro-mastered CD through a pair of 1 1/2 inch speakers. It loses most of the dynamics. most of the range, and all of the original mix. .AIFF is compressed and squashed enough, anything less is a demo, not a good sounding mix.

MP3 is convenient, but sounds like a steaming turd.

[CrackedButter]

I have heard alot about another file format called .ogg, and this is superior to mp3 as well, how does this fit in, alot of people have .ogg files as well.

[deepkid]

Originally posted by Steamboatwillie
I encourage anyone interested to go to http://r3mix.net/ and read about it.

Hey, thanks for the info. Where is the MAC version of this? :)

[deepkid]

Originally posted by ennerseed

I have thousands ( 4221 ) of mp3s, I could re-rip but they are from vinyl and are a pain in the a** to record, much less tag properly.

Amen. However, you should *always* keep uncompressed digital copies of your vinyl-transferred audio. Even if you keep it on cheap CDRs, it would allow you to go back to an AIFF, WAV in order to rip using another codec.

I have thousands of vinyl records and after calculating how long it would take me just to digitize them as AIFFs, I just walked away shaking my head.

Now if someone could come up with some sort of *scanner* that would allow me to digitize my vinyl much like reading bar codes... oh boy... they would have my wallet!

Imagine walking past a stack of records *waaawwnngggg* AIFFs. Even if it made one huge AIFF that I had to disect, no problem.

[eric_n_dfw]

Originally posted by Steak
Not that I'm against a new format. but this story is a load of crap. Anyomne with even half an ear, can hear a vast difference between an MP3 at 256kb, and original CD file. cd's sound bad enough, Mp3, or Mp4, sounds bad. 256kb p/s doesnt help with MP3's harsh, mid-heavy crappy sound. An MP3 is like listening to a pro-mastered CD through a pair of 1 1/2 inch speakers. It loses most of the dynamics. most of the range, and all of the original mix. .AIFF is compressed and squashed enough, anything less is a demo, not a good sounding mix.

MP3 is convenient, but sounds like a steaming turd. Then, unless you are storing everything in uncompressed format, what's your point? MP3 and MP4 are good enough for the masses and that's where the money is.

[crush7]

Originally posted by Abstract


Is this AAC going to be better than "almost lossless", because I sure can't see anything compressed as being completely lossless.

It all depends on your listening habits and on the equipment you use. The music also plays an important role. I for instance listen mostly to the original CDs or even the LP, when it is available. MP3s are only good on the road or in the iPod.

I wonder just how much of the "AAC is indistiguishable from CD at 225bps" is marketing, and how much is truth.

[eric_n_dfw]

Originally posted by deepkid
Now if someone could come up with some sort of *scanner* that would allow me to digitize my vinyl much like reading bar codes... oh boy... they would have my wallet!

Imagine walking past a stack of records *waaawwnngggg* AIFFs. Even if it made one huge AIFF that I had to disect, no problem. Your wish is my command! Check this out: http://www.cs.huji.ac.il/~springer/

(Doubt it's the quality you're looking for though!)

[deepkid]

Originally posted by eric_n_dfw
Your wish is my command! Check this out: http://www.cs.huji.ac.il/~springer/

(Doubt it's the quality you're looking for though!)

I remember reading about laser turntables a decade or so ago... I wonder how much progress has been made? But then again, the goal would be to avoid real-time conversion.

I'd like to see the scanner referenced above.. wonder what progress has been made there.

Thanks.

[Steamboatwillie]

Originally posted by impierced
The "--r3mix" has been superseded by the "archive quality" "--alt-preset standard" for lame encoding.

--r3mix will be a bit smaller at good quality, but the --alt-preset standard will sound much better.

Do a blind test on your hi-fi system and I think you'll agree.

Indeed I will, thank you for pointing it out. Just as a point of reference this is a list of the equipment I will be using to compare the LAME switches:

- B&W 602DM Speakers
- Transparent "The Link 100" Bi-wired Speaker Cable
- Rotel RB976 Six Channel Amplifier (Running 4 channels for Bi-Amped mode)
- Creek OHB-12 Passive Pre-Amp
- Musical Fidelity X-10D Buffered Tube Stage
- Musical Fidelity X-ACT 18-bit 48kHz DAC
- 2 Monarchy Audio DIP's (Anti Jitter)
- Kimber Kable Digital X 75-ohm digital cables
- Kimber Kable Silver Streak interconnect cables (RCA unbalanced)
- MOTU 2408 (Digital SPDIF out from my computer)

As soon as I get a chance I'll encode some of my best cd's (best quality recordings) and do some tests. Of course sound is highly objective so whatever my findings are just an opinion.

[ennerseed]

hmmmm uncompressed copy, on cd... or dvd.... ..... .. . ****.

- a tear slowly falls through the air, then crashes on his desk with a sound of thunder (at 192-kHz) -

[pseudobrit]

Originally posted by Steak
Not that I'm against a new format. but this story is a load of crap. Anyomne with even half an ear, can hear a vast difference between an MP3 at 256kb, and original CD file. cd's sound bad enough, Mp3, or Mp4, sounds bad. 256kb p/s doesnt help with MP3's harsh, mid-heavy crappy sound. An MP3 is like listening to a pro-mastered CD through a pair of 1 1/2 inch speakers. It loses most of the dynamics. most of the range, and all of the original mix. .AIFF is compressed and squashed enough, anything less is a demo, not a good sounding mix.

MP3 is convenient, but sounds like a steaming turd.

TEHO, I guess.

I have all my iPod music compressed at 160kbps and it seems okay. At home I run 7.1 and I've got a factory Monsoon in the car and for all I'm worth I don't notice much of a difference if any.

I guess the question becomes one of usability. What good is *perfect* sound if I have to listen to it on studio master tapes and equipment? A CD might not sound perfect, but it's convenient and usable; MP3 even moreso. I can easily carry and access over 1100 songs on my 5GB scollwheel iPod.

I'd rather put up with imperfect music and have 100 CDs worth of music crammed into the size of a cigarette pack. How many pounds of vinyl or studio master tape would that equal?

[Jeff Harrell]

Just for fun, I just did my own MP3-MP4 taste test. It's not remotely scientific, so if you folks wanna argue about my methodology, that's fine, but don't get all worked up about it.

For my subject matter I picked the track "Beautiful Day" from the U2 album "All That You Can't Leave Behind." I chose this track for two reasons: first, because I happened to have the CD sitting here on my desk, and second because I noticed some weeks ago that a 128 kbps MP3 of this song ripped with iTunes sounds like chisled spam, and even a 160 kbps MP3 ain't all that great.

I opened the AIFF file in QuickTime Player and exported it as a 128 kbps MP4 at 128 kbps using a sample rate of 48 kHz and "High" encoding quality.

The results astounded me. I loaded both the AIFF and the MP4 up in QuickTime Player, then used the "Play All Movies" feature. I toggled back and forth between the two, and yes, by God, they were indistinguishable to me. I am no audiophile, but 128 kbps MP3's generally make me cringe, so I guess you'd call my ear "semi-educated," for what that's worth.

I then did the same test with the 128 kbps MP4 and a 192 kbps MP3 ripped through iTunes. The MP4 sounded a bit better. In particular, in the first minute of the song, listen to the high hat. The MP3 muddies it, though it's not shredded like it is at 128 kbps. The MP4 preserves it. I'll say it again: a 128 kbps MP4 sounds slightly better, and certainly no worse, than a 192 kbps MP3.

I'm amazed. A 3.8 MB file sounds better than a 5.6 MB file, and very nearly as good as a 42 MB AIFF.

I'm hooked! Sign me up! Where's that iPod firmware update enabling .mp4 playback?

[avkills]

I hear people complaining of no bass in their MP3s...if you are using iTunes to encode then you do know that there is a low-frequency filter than you can turn off, of course it says the cut-off is 10Hz, but I always turn it off anyway. Another problem could be the *el-cheapo* sound systems beaing used to play them. I don't care which brand of "computer systems" you buy, none of them are high-end stuff. Granted, the source CDs will always sound fuller, but I see no major depreciation in the low frequencies on my MP3s.

I'm surprised no one has mentioned MiniDiscs. Sony's minidisc systems compress as well, and they seem to sound half way decent.

Oh well, since I've invested in some "real" audio gear for my home setup, I've decided that if I "really" want to listen to some music, I will just put the CD in. :D

-mark

[SoonToGetAMac]

Originally posted by avkills


I'm surprised no one has mentioned MiniDiscs. Sony's minidisc systems compress as well, and they seem to sound half way decent.


-mark

Sony uses ATRAC or something like MP3 but with DRM stuff, right?

[RBR2]

Originally posted by ennerseed
just some personal thoughts...

I would keep you mp3s as they are.

i would re-rip your cds to aac... this time make sure it sounds good to you!

I have thousands ( 4221 ) of mp3s, I could re-rip but they are from vinyl and are a pain in the a** to record, much less tag properly. I have totally stoped recording my records till I find out what the final deal is with aac, iTunes, iPod.

As time went on I went from 128k to 320k and really wish this stuff came, would be coming, about faster.

Thanks for the info Arn

_______________________________

One of these days I need to copy a bunch of vinyl to digital. Maybe the new compression standard will be out by then. Are you using anything in particular to clean up the pop/scratch noises from the vinyl? I have Toast Titanium that has some sort of program that is supposed to do that, but I have not tried it as yet. Are there others? Better ones?

Thanks!

[ennerseed]

Originally posted by RBR2
_______________________________

One of these days I need to copy a bunch of vinyl to digital. Maybe the new compression standard will be out by then. Are you using anything in particular to clean up the pop/scratch noises from the vinyl? I have Toast Titanium that has some sort of program that is supposed to do that, but I have not tried it as yet. Are there others? Better ones?

Thanks!

Stienberg makes a vst plugin called declicker, as to its quality, I don't know.

I tried running some other filters over some tracks and messed up the range too much.

Added - http://pub41.ezboard.com/fr3mixfrm1.showMessage?topicID=564.topic

[Rincewind42]

Originally posted by Jeff Harrell
I opened the AIFF file in QuickTime Player and exported it as a 128 kbps MP4 at 128 kbps using a sample rate of 48 kHz and "High" encoding quality.

Actually, using a sample rate of 48khz on a CD-Audio file will probably decrease the quality since QT will have to upsample the audio (from 44.1->48) which is not a good conversion to do. If you are going to rip from QT, use the 'Recommended' sample rate setting - it will use the current sample rate of the song.

[abdul]

Stupid question but ot hought that AAC and MP4 were two copletely different formats. I guess thats not true is it? I also thought that Panasonic made AAC, is that npot true either?

[bennetsaysargh]

aac is the audio to an mp4 file.

[CrackedButter]

Nobody interested in .ogg then?

[SoonToGetAMac]

Originally posted by CrackedButter
Nobody interested in .ogg then? I don't think it has the possibility to include DRM. Also, .mp4 sounds like an upgrade .mp3, so people would be framiliar with the name, whereas .ogg would be a new filename.

[bennetsaysargh]

the ogg format has been around for a while, but only familiar with a few people. i've never tried it, but as it's been said, it sounds like an upgrade and people are familiar with mp3. my grandparents know what they are for gosh sake!

[arn]

Originally posted by SoonToGetAMac
I don't think it has the possibility to include DRM. Also, .mp4 sounds like an upgrade .mp3, so people would be framiliar with the name, whereas .ogg would be a new filename.

besides... it is expected that Apple will release an AAC supported iPod and iTunes... while ogg may not get as much support.

arn

[CrackedButter]

It would be nice if they did, but i was more interested in how .ogg compared to mp3 and AAC on a technicial side, forgetting DRM for the moment.

[bennetsaysargh]

if someone has the time, could they do a quality test or something like that for mp3 mp4 and .ogg? i want to know how much better it is, and how much of a difference it is in the file size.

[arn]

Originally posted by bennetsaysargh
if someone has the time, could they do a quality test or something like that for mp3 mp4 and .ogg? i want to know how much better it is, and how much of a difference it is in the file size.

With something as subjective as audio quality -- it's going to be hard to get a quantitative "how much better" one is than the next.

There was one study that placed ogg higher than AAC in quality.... but until Apple offers ogg as a simple option in iTunes/iPod as easy as mp3 or AAC (presumably will be) -- then it's a moot point for me.

If you really care about it, you should encode your favorite songs in each format. Then decompress them to a raw AIFF file. Have a friend randomize them and play them on the same hardware, but not tell you which one is which.

arn

[docpsycho]

[QUOTE]Originally posted by porovaara
[B]What does this sound like to you? (Honestly curious). For those who can't hear the difference between mp3s done at things like 128-196, etc... try the following:

Get the source CD. Pick out a specific percussion instrument or the strongest portion of the bass line. Listen to it. Now play the mp3 specifically listening for that portion only. You should notice a definite difference in crispness, strength and clarity. You can also do this with strong voice performances, try a piece of opera. But the best overall way I've found to demonstrate the difference between mp3 bit rates is classical music. mp3 at lower bit rates absolutely murders the full-bodied sound of an orchestra.

SOUNDSTAGE . . . THE 3RD DIMENSIONABILITY(talk about hacking the english language) The mind being able to perceive 3 dimensions of the recording. I still can hear compression at 320 rates . . . in the high freqs . . .crash cymbols, reverbs cut of faster . . . etc.

[Rincewind42]

For everyone that has posted about how MP3 sounds like crap at even 256+ how about this: Maybe not all of us want a trained ear. I rip mp3 at 192 right now because I heard something nasty in one track a couple of years ago, but it is likely that there is a lot of my collection that could be ripped at 128 and I wouldn't even notice. If my ear were trained to hear it, I wouldn't enjoy my music except by putting the bloody CDs in the drive to listen to them!

If you are really so unhappy about mp3 at 256+, then you should be happy that aac is here. It gives better performance than mp3, so your 320 aacs outta sound better than your 320 mp3s. And if it doesn't, then what loss is that to you =).

Let the rest of us with normal ears just revel in the joy that will be (at least for us) CD quality audio at 1/2 - 2/3 the previous file size.

[bennetsaysargh]

Originally posted by Rincewind42
For everyone that has posted about how MP3 sounds like crap at even 256+ how about this: Maybe not all of us want a trained ear. I rip mp3 at 192 right now because I heard something nasty in one track a couple of years ago, but it is likely that there is a lot of my collection that could be ripped at 128 and I wouldn't even notice. If my ear were trained to hear it, I wouldn't enjoy my music except by putting the bloody CDs in the drive to listen to them!

If you are really so unhappy about mp3 at 256+, then you should be happy that aac is here. It gives better performance than mp3, so your 320 aacs outta sound better than your 320 mp3s. And if it doesn't, then what loss is that to you =).

Let the rest of us with normal ears just revel in the joy that will be (at least for us) CD quality audio at 1/2 - 2/3 the previous file size.

that's exactly right
if you are too busy paying attention to the bit rate of the music, then you shouldn't even be allowed to listen to it. 256 takes up a lot of space, and is very good, but i don't need trained ears to enjoy music

[docpsycho]

Originally posted by bennetsaysargh
that's exactly right
if you are too busy paying attention to the bit rate of the music, then you shouldn't even be allowed to listen to it. 256 takes up a lot of space, and is very good, but i don't need trained ears to enjoy music

Whell then why Do U have a MAC???? why not use windows instead? Why would you want to be a lemming?? "got steep cliff?" see that the prob you don't care . . . only when you'll need hearin' aids, the shoulda coulda woulda will come back to bite you in the ass hard. if there is anything left off it from other things that come back . . .from half assin' it!!!!!!

been there, done it, lesson learned . . . . ah life what an experience!!!!

[Rincewind42]

Originally posted by docpsycho
Whell then why Do U have a MAC???? why not use windows instead? Why would you want to be a lemming?? "got steep cliff?" see that the prob you don't care . . . only when you'll need hearin' aids, the shoulda coulda woulda will come back to bite you in the ass hard. if there is anything left off it from other things that come back . . .from half assin' it!!!!!!

been there, done it, lesson learned . . . . ah life what an experience!!!!

Don't make this a mac vs pc thing, it's not and is far, far from it. I enjoy my music just fine without trying to listen for all the compression artifacts that a trained ear may or may not hear. I don't have the time or will to look for them. I want my music to just work (sounds familiar does it not?). And my music works a lot better as 5MB mp3 files than it does as 50MB aiff files coming off a CD. I predict that I will enjoy much more music in the same amount of space as 3MB aac files. Either way being aware of the compression artifacts doesn't do that for me, but instead makes me annoyed that there isn't a better way (I know that sounds familiar... :D). If you don't like your music compressed, then don't compress it - copy the audio files from the CD to your 500GB HD. But don't tell me that because I like compressed audio that I'm a lemming or that I have a tin ear because I won't care - I'll just keep on ripping my mp3s/aacs.

[SwitchMonkey]

Ummm.. be careful.. there is no such thing as "MP4".

More specifically, the thread author stated that AAC is the audio track of the video standard known as MPEG4.

I believe MPEG4 is the format video DVDs are encoded in. Please correct me if I'm wrong here.

Panasonic using AAC? me not know...

Originally posted by abdul
Stupid question but ot hought that AAC and MP4 were two copletely different formats. I guess thats not true is it? I also thought that Panasonic made AAC, is that npot true either?

[SwitchMonkey]

Cool thread,
when do we start the MIDI thread?

[eric_n_dfw]

Originally posted by SwitchMonkey
Ummm.. be careful.. there is no such thing as "MP4".

More specifically, the thread author stated that AAC is the audio track of the video standard known as MPEG4.

I believe MPEG4 is the format video DVDs are encoded in. Please correct me if I'm wrong here.

Panasonic using AAC? me not know... DVD's are in MPEG2, their audio portion is in Dolby AC3 (AAC also is available under MPEG-2 but I don't know if DVD's use it)

An interesting note, if you use Quicktime to export an audio file to MPEG-4, AAC format, by default it gives it an .mp4 file name extension.

[niels]

Okay, a little bit of background information about MPEG-4 and AAC.

The MPEG-4 standard was designed by the Motion Picture Experts Group, which is also responsible for MPEG-1 and MPEG-2.
The group consists of many different companies who all work together to set standards. The companies all bring in specific parts which is then licensed to MPEG-LA. Other companies who want to use the MPEG standard can then take a license for the complete standard from MPEG-LA, who makes sure every company that contributed to the standard gets paid. For example: The QuickTime container format is used by the Motion Picture Experts Group as the official MPEG-4 container format.


** updated (begin) **

MP3 is actually called MPEG Layer 3 and is part of the MPEG-1 specifications. MPEG-1 consists of three different audio compression formats called Layer 1, 2 and 3 a.k.a. MP1, MP2 and MP3.

There are many differences between the Layer 1, 2 and 3. The higher the Layer, the more complex the format is, the less space it takes to store a piece of audio of the same length. So MP3 is more complex than MP2, which in its turn is more complex than MP1. MP3 offers the best compression.

All of the different Layers were based on already existing technologies created by many different companies.

The MP1 format is also known as PASC, which was used by Philips for their failed DCC (digital compact cassette).

The MP2 format is also known as MUSICAM and is mostly known from the usage on VCDs and SVCDs.

The MP3 format was contributed to the Motion Picture Experts Group by Fraunhoffer IIS and Thomson (known in the US as RCA). The format was originally created as part of EUREKA, a european project for digital audio broadcasting (DAB).

MPEG Layer 4 does not exist

** updated (end) **


The MPEG-2 format is mostly known from DVDs. The DVD forum (a different group of movie studios and consumer electronics manufacturers) decided base their DVDs on the MPEG-2 standard. But the DVD standard is not the same as the MPEG-2 standard. There are many other products which uses the MPEG-2 standard such as digital set-top boxes.


** updated (begin) **

With the introduction of MPEG-2 a new audio formats was introduced as well, but at the time it wasn't used much. The format is called AAC and was created by Fraunhoffer IIS in collaboration with Dolby, Sony and AT&T. This format is now refered to as MPEG-2 AAC.

The older Layer 1 - Layer 3 formats (MP1-MP3) were updated and are also part of the MPEG-2 standard. The MPEG-2 Layers are backwards compatible with MPEG-1. The only difference between the MPEG-1 and MPEG-2 versions are the number of channels that are supported.

On DVDs MPEG-2 is mostly used together with the AC-3 codec, developed by Dolby, but the AC-3 codec isn't part of the MPEG-2 standard. The DVD forum decided to deviate from the standard because of licensing issues. The AC-3 format was already a widely used format for digital audio in theaters. So DVDs are not 100% compatible with the MPEG-2 standard, but it is based on it.

** updated (end) **


The MPEG-4 format is the latest standard set by the Motion Picture Experts Group. MPEG-4 is a still expanding standard which is become more and more populair. Because Apple contributed their QuickTime container format they get paid for every MPEG-4 license sold, which is probably also one of the reasons they want to see this standard become populair. The MPEG-4 standard is pretty large and has a many different ways to compress both audio and video.

The preferred way to compress audio according to the MPEG-4 standard is by using the AAC format. Please note, this isn´t the same AAC as using in the MPEG-2 standard, the official name for the *new* AAC is MPEG-2/4 AAC. After AAC was introduced in MPEG-2, the creators made a number of improvements to make the quality even better. AAC isn't the only MPEG-4 audio format, other audio standards such as the old MPEG Layer 3 (MP3) are still allowed.

Confused already? No... don't worry you will be in a minute.

As I mentioned already the MPEG-4 container format is based on QuickTime. But what is exactly a container format? Well, think of it as a box in which you can store different things. The box contains a couple of audio tracks, a video track or possible even subtitles. The box is just a small part of the MPEG-4 standard, but it describes how all these different formats can be mixed into one little neat file.

The older MPEG standards also used a container format called .mpg, but it was very different from the MPEG-4 container format. Basically every movie file that also included audio is placed in a container format, for example .mov, .avi or even .rm.

Without a container format you would need a couple of different files to store all the information. For example instead of a simple .mpg file on a VCD disc, you would have an .mp2 file for the audio and a .mpv file for the video.

An .mp3 is nothing more than a MP3 track which isn't placed inside the .mpg container format.

Because MP3 became very popular the Motion Picture Experts Group decided to give their new MPEG-4 standard a boost by using .mp4 as the official extension for the MPEG-4 container format. So if you see a file ending with the extension .mp4 it will be a MPEG-4 file.

Unlike an .mp3 file which is just an audio track, the .mp4 file is an container format, so it can contain video and/or audio. Most likely AAC would be used to encode the audio, but that is not always the case. Basically you can't be sure what the .mp4 file contains without opening it. It could be very possible the .mp4 file contains a single MP3 audio track.

Just like MP3 and .mp3 files, you can store AAC audio tracks without using the MPEG-4 container format. These files can be recognised by the .aac extension.

[CubeHacker]

Originally posted by CrackedButter
It would be nice if they did, but i was more interested in how .ogg compared to mp3 and AAC on a technicial side, forgetting DRM for the moment.


If anyone cares, I did some tests comparing mp3, mp4, and ogg. The results were quite surprising, especially on the low bitrate end of things.

I compared all three formats at the lowest possible levels of 48kbps, using some music with a lot of high frequencies. Not surprisingly, the mp3 sounded horrible - like it was comming through a telephone or something. I didn't bother with VBR mp3's, so that might have helped a little, but i doubt too much. Keep in mind that I was using LAME as the encoder, hailed as the best.

Next came the AAC mp4 file, which is natively VBR. Using quicktime to encode the file at 48kbps, the sound quality was a step above the mp3, but nothing ground shattering. Most of the high frequencies were still missing, and it sounded like someone put a pillow in front of the speakers.

Last was the Ogg Vorbis at 48kbps, also natively VBR. Now this was the shocker - the ogg at this horribly low bitrate sounded 95% CD quality! Almost all of the high frequencies played, and although there was a very slight wavering effect in the background, it sounded remarkably good. As a matter of fact, i later did some tests, and it seems the 48kbps ogg sounded BETTER than a 128k mp3!

So who the heck would ever encode at 48kbps? Well, you're right. If you're planning to stick music on an ipod, there is no reason to skimp on the quality with all that space available. But these low bitrate files are useful in 2 areas - flash memory mp3 players, and online streaming. Unfortunatly, no flash memory mp3 players can play ogg files that I know of. It would be great if they did.


I DID do some tests with 128kbps files, using two different kinds of music - pop and classical. There was no real audiable difference between the three formats playing the pop music, although the mp3 did display some small artifacts. The ogg and mp4 sounded CD quality. The real test was with the classical. The mp3 file really showed its weakness here, and there was a *lot* of artifacts in the music, especially in the string instruments. The ogg and mp4 sounded perfect, although I think the ogg sounded a bit "cleaner".

If you want the audio samples I used to do this comparison, feel free to PM me and i'll be happy to send you the files.

I really do hope that Apple supports Ogg Vorbis, as I feel its time we started to move away from closed formats. Ogg is free and sounds far better than mp3, so I don't see why it shouldn't be used! And while Mp4 also sounds great, it requires royalty fees to use.

[SwitchMonkey]

That was veddy educational, thanks niels

Originally posted by niels
Okay, a little bit of background information about MPEG-4 and AAC.