Big-label mastering engineers don’t understand lossy formats, Article about Mastered for iTunes Options

[Kohlrabi]

Just found this article via twitter, circled among mastering "engineers" (in fact Heba Kadry reposted it, the girl who mastered the latest Mars Volta album, which reaches -12.79 dB on my RG scans, and is generally mastered in a horrible fashion).

This further backs my impression that most of them don't have a single clue of what they are doing. The section about the mastering practices of Rubin and Meller are especially eye-opening to me. Masterdisk "engineers" also apparently are now out to rape the Rush back catalogue. Further down they cite phase-reverse tests to prove AAC files are different from the original (wow, REALLY?).

The good thing is, I can use this article to decide which releases to avoid in the future. But I'm really at a loss what we can do beside that. I'm really fed up with mastering "engineers" destroying music releases.

This post has been edited by Kohlrabi: Mar 27 2012, 09:17

[evereux]

Apple’s 256 kbps AAC files are supposed to sound pretty close to CD-quality and they routinely fool listeners in double-blind listening tests. But when record-producer/living-legend Rick Rubin heard the iTunes version of his new Red Hot Chili Peppers production I’m With You, he was reportedly appalled by how its sound changed during the conversion process.

“He was horrified,” Grammy-winning mastering engineer Vlado Meller told me when I visited him at Masterdisk.

“It was as if they had notched out certain frequencies in order to compress the file. The highs were missing and the lows were missing. The mids and the high-mids sounded like they were filtered out. When we did the A/B test with the original and the iTunes release it was like it was two different masters. If it wasn’t for [Rubin] making a stink and putting his weight behind it, we wouldn’t have this today. He deserves the credit for that.”

This makes me so sad.

[skamp]

They obviously think what they do is teh shit. Normal people think it sounds great. I remember when I first listened to Californication during New Year's Eve 1999-2000: loved the album, didn't complain about how it sounded. I developed the tastes I have now over several years, and I think it would be fair for others to qualify me as being anal.

What we have here is a mix of different tastes, a bunch of misconceptions, a certain lack of education, and perhaps straight up incompetence in certain cases. What can we do?

Fortunately, some albums still come out sounding great.

[2Bdecided]

I think you're being a little harsh on the article.

One thing amazed me though...

Bob Ludwig of Gateway Mastering, who is known for his objectivity and diligence, said "…[Another] important addition is the realization that the act of AAC encoding can cause clipping where there was none on the original PCM .wav or .aiff file"

This is news to a diligent mastering engineer? Has he just stepped out of a time machine from 1996?!


I haven't looked into "mastered for iTunes" - it seems strange to "need" to EQ a track to compensate for the effects of an AAC encoder running at 256kbps.

Cheers,
David.

[Kohlrabi]

I think you're being a little harsh on the article.

I'm a little anxious right now, because I tried to listen to "Noctourniquet" by The Mars Volta and got all angry.

I haven't looked into "mastered for iTunes" - it seems strange to "need" to EQ a track to compensate for the effects of an AAC encoder running at 256kbps.

Please understand how these people roll. They don't understand perceptual encoding. They don't understand that AAC encodes merely are intended to sound like the original. I guess they sit in front of their mastering software and see that the waveforms differ, and then start to fiddle with the stream they send into the encoder until the waveforms match better. I have no definitive proof of that, but the phase-inversion comparison gives me the strong impression that this is the case.

Just to make it clear, I don't intend to give disrespect to mastering engineers or engineers in general, just to the breed which completely abandoned, or never acquired, understanding of digital audio, and still sprout their bullshit all over the internet, and keep destroying legit good music. They are a disgrace to the engineering community.

This post has been edited by Kohlrabi: Mar 27 2012, 09:50

[KMD]

Thats round the wrong way, the article said the waveform shapes were not the relevant factor it was the person skeptical of mastered for itunes that was looking at the sum of two file with one inverted.

[Nessuno]

Just to make it clear, I don't intend to give disrespect to mastering engineers or engineers in general
[...]
They are a disgrace to the engineering community.

Actually, americans have a rather imaginative way to use the word "engineer"...

[Porcus]

I bet the people behind Monkey's Audio will want to bomb a certain kohlrabi with rotten bananas over this comparison.

[DonP]

Just to make it clear, I don't intend to give disrespect to mastering engineers or engineers in general
[...]
They are a disgrace to the engineering community.

Actually, americans have a rather imaginative way to use the word "engineer"...

There are several senses of it.

1) a guy who drives a train

2) Someone who puts science into practice. Generally considered as needing at least a BS/BE degree in the field and for some disciplines, a license.

3) Someone looking to dignify his job, like a janitor calling himself a sanitation engineer. In fact, sanitation engineers design things like sewage and water treatment plants.


As I understand, in Britain machinists are called engineers, but not in the US.

This post has been edited by DonP: Mar 27 2012, 12:57

[dhromed]

I'm a little anxious right now, because I tried to listen to "Noctourniquet" by The Mars Volta and got all angry.

I don't consider the new album (and the one previous to that) to be as harsh as the earlier ones, but subjectively I find it less interesting. It's just a shame that the earlier albums break one's ear drums, because on purely musical terms, I think they're very good. That is what saddens me. It's like putting on a light show but you shine all the spotlights directly in people's faces.

[RobWansbeck]

Vlado Meller is reported as saying :

“ The highs were missing and the lows were missing. The mids and the high-mids sounded like they were filtered out. “

Seems like everything was missing. Perhaps he forgot to turn the volume up!

[greynol]

http://www.hydrogenaudio.org/forums/index....st&p=787986

[Arnold B. Kruege...]

Thats round the wrong way, the article said the waveform shapes were not the relevant factor it was the person skeptical of mastered for itunes that was looking at the sum of two file with one inverted.

That is very sad as well.

That goes back to knowing what a perceptual coder does.

The one question that really matters is whether or not they've done reliable listening tests. The expected answer is "No".

BTW, Bob Ludwig is probably about my age.

[TrustScience]

I think you're being a little harsh on the article.

Thats round the wrong way, the article said the waveform shapes were not the relevant factor it was the person skeptical of mastered for itunes that was looking at the sum of two file with one inverted.

From the Author

Thanks for sharing the article, Kohlrabi. If you have another read of it sometime, I think you'll find it's pretty even-handed.

I get the sense that you disagree with the claims made by the mastering engineers, and not with the article itself, which tries to take a neutral stance.

Since this was piece of reportage, rather than opinion, I wanted to accurately deliver the news, present both the commentary and the criticism, and to offer some dispassionate analysis of both stances. The article tries to remain skeptical of the magnitude of the claims, but I also stand by the fact that it's unfair to dismiss them entirely without proper tests.

If you do want to read an opinion piece, you'll probably find that my own feelings about blind listening are pretty congruent with the philosophy here at Hydrogen Audio. I'm a big supporter of this site and of ABX tests in general, and I even wrote a supportive opinion piece about blind listening tests in the very same issue you cited! (You can read that here):

"Can You Hear What I Hear? A Guide to Listening Blind"

I will have to disagree with the extreme stance that mastering engineers are generally snake-oil salesmen (I've never had an experience that would lead me to believe that) or that Mr. Ludwig or Ms. Kadry are incompetent (I know both, and they're definitely not).

However, as a matter of personal opinion, I would agree that Rick Rubin overstates the audible differences normally found between high-res AAC files and their original WAV masters. I'd also agree that at least one of Meller's comments was probably more figurative and expressive than it was literal.

With that said, the engineers I interviewed told me that in "Mastered for iTunes", Apple also fixed an actual issue they had in the past with creating AAC files from high-resolution masters. To be fair, even Bob Ludwig agrees that 256kbps files won't necessarily sound any worse than traditional CD files - Just so long as they're created properly, and the engineer can verify there were no issues with the transfer. (He says that this is something that they're now able to do.)

The other real development appears to be that MEs can now easily and effectively hear the differences between their original master and the file that the iTunes store's proprietary encoder will create. (I'm told that, for better or worse, it's not the same encoder used in the consumer version of iTunes.)

Who knows? Even if the AACs sound identical in 95% of cases, this new ability to actually listen and check can't be a bad thing

Personally, I think the new tools are a good idea, but I'm not about to replace my music library with new "Mastered for iTunes" versions anytime soon.

I definitely appreciate the healthy dose of skepticism here on Hydrogen Audio, and would agree that people who have a service or product to sell sometimes dramatize their claims... But show me a salesman who doesn't, and I'll show you a salesman who's out of a job!

Thanks again for the share and the comments. Keep doing what you guys do!

Very best,

Justin Colletti
Recordist, Journalist
http://justincolletti.com
http://trustmeimascientist.com
http://sonicscoop.com

[Canar]

show me a salesman who doesn't, and I'll show you a salesman who's out of a job

If that's the case, I fully support sales staff unemployment.

[saratoga]

I get the sense that you disagree with the claims made by the mastering engineers, and not with the article itself, which tries to take a neutral stance.

Since this was piece of reportage, rather than opinion, I wanted to accurately deliver the news, present both the commentary and the criticism, and to offer some dispassionate analysis of both stances.

Yes, clearly people are mostly annoyed by how clueless some of the people doing the mastering are. That Bob Ludwig quote where he seemingly does not understand what audio encoding is or why it might cause clipping is particularly galling from someone doing any sort of audio work. Particularly to people like me who consider the huge amount of clipping accidentally introduced by incompetent engineers to be one of the worst aspects of modern music.

The article tries to remain skeptical of the magnitude of the claims, but I also stand by the fact that it's unfair to dismiss them entirely without proper tests.

Yes of course, however some of the stuff you say is just ... odd. For instance:

First is that Sheperd’s sample size of one song is far too small to be conclusive — especially with a manual process like mastering for iTunes.

Second is that Sheperd’s methodology is flawed. He takes a song that was mastered in August, before the new protocols were in place, and then uses both a lower bit-depth source-file and a different AAC encoder than was used to create the “Mastered for iTunes” version.

With all that in mind, it would be no surprise if Shepherd’s results are different. He then continues to compare his own custom file to a down-sampled CD version rather than the original high-resolution master. In his test, Shepherd also neglects to run either a blind ABX test or an objective frequency analyzer to verify which version of the file could be shown to sound more similar to the original during normal playback.

Even if Shepherd fixes his methodology, there’s still a third argument that could call his analysis into question: Since the Mastered for iTunes process uses a healthy dose of additive EQ to restore frequencies that are lost during the AAC conversion process, it’s plausible to suggest that the phase-shift inherent in all non-linear EQs could cause his phase-based null test to report additional cancellation differences — even if the EQ was successful in restoring the original frequency balance.

No, first everything that clown says is irrelevant since you can't show that one encoding is closer to CD by subtraction. Its not that his sample size is too small its that his test is meaningless. Its not that he took a song mastered at the wrong time, its that he doesn't know what hes doing. Why are you talking about EQ when nothing he says could possibly make sense? Actually, why are you even addressing this guy aside from to say "no I'm sorry, thats not how audio works"?

I will have to disagree with the extreme stance that mastering engineers are generally snake-oil salesmen (I've never had an experience that would lead me to believe that) or that Mr. Ludwig or Ms. Kadry are incompetent (I know both, and they're definitely not).

That part where Ludwig discovers that very loud digital files can easily clip when you do any sort of lossy processing, was that taken out of context? Because by implying that hes unfamiliar with digital processing you make him sound utterly incompetent . . .

[Fandango]

show me a salesman who doesn't, and I'll show you a salesman who's out of a job

If that's the case, I fully support sales staff unemployment.

Me too.

The main characteristic of snake oil is that the one who sells it claims it can do stuff, it in reality cannot. Another not so well known characteristic is that snake oil might actually do stuff that the salesman is either unaware of or if he is he is silent about it...

With that said, the engineers I interviewed told me that in "Mastered for iTunes", Apple also fixed an actual issue they had in the past with creating AAC files from high-resolution masters. To be fair, even Bob Ludwig agrees that 256kbps files won't necessarily sound any worse than traditional CD files - Just so long as they're created properly, and the engineer can verify there were no issues with the transfer. (He says that this is something that they're now able to do.)

The other real development appears to be that MEs can now easily and effectively hear the differences between their original master and the file that the iTunes store's proprietary encoder will create. (I'm told that, for better or worse, it's not the same encoder used in the consumer version of iTunes.)

So they're telling you that they have basically added a signal that they can audibly perceive later on when playing the AAC? And Apple even uses a special version of their encoder to ensure the signal is not extenuated? For what? To ensure the encoding process didn't "damage" the music too much? I've never heard of a more ridiculous process. "Mastered for iTunes" is a sound degrading watermark, really?

[greynol]

the Mastered for iTunes process uses a healthy dose of additive EQ to restore frequencies that are lost during the AAC conversion process

Citation please!

[Fandango]

@greynol: Oh, here it is explained by a guy named Bob Ludwig, he says some funny things along the way but I think the concept behind "Mastered for iTunes" should be somewhat clearer now. Whether it's the only processing "Matered for iTunes" is capable of remains unclear, I guess.

4: Speaking of compression, many people believe you cannot get a download to sound good no matter what you do. I disagree, not that I feel the overall dynamics of a download can equal that of an LP (or can they)—but I play a great deal of downloaded music at home through a decent DAC and system, and I'm surprised at how good it can sound. Do you master things differently for iTunes for example?

Bob Ludwig: Apple has begun a new initiative called "Mastered for iTunes" which greatly improves the sound of iTunes AAC encodes without changing a single piece of hardware on the 250,000,000 players in the field. It can be so dramatic you can easily hear the difference between the new and old technology on your little laptop speakers.

Instead of ingesting the music from a CD rip or 16-bit file, the new system uses 24-bit master files for the encode. The AAC encoder can make use of bits 17-24. An important addition is the realization that the act of AAC encoding can cause clipping where there was none on the original PCM .wav or .aiff file. In classical music this encoder induced clipping can occur at the occasional climaxes or in a typical over-compressed pop/rock recording, many times a second. Apple has created tools to log the number, severity and time of each clip so the mastering engineer can lower the level of the 24-bit master by fractions of a dB and the clips and resulting distortion from them is eliminated.

It is a complicated answer, but a 24-bit AAC encoded file can thus sound better and measure better in certain cases than a normal 16-bit Compact Disc, which unfortunately has been regarded as the gold standard for sound in these comparisons.

Well, I'm not that into the matter of lossy encoding, but can't you just make a 16bit master that is not that freaking loud and brick-walled and have the same effect at the end? The whole "Mastered for iTunes" fad is like a cruel joke when the industry is putting out crap like this:

I'm a little anxious right now, because I tried to listen to "Noctourniquet" by The Mars Volta and got all angry.

So you only got a little anxious and angry? Why didn't you scratch your eyes out, poked your eardrums and shredded your skin when listening to this joke of an album?

When I tried listening to it, it sounded as if something was wrong with my speakers, like if a driver was dead. Or as if my amplifier was broken. No kidding. Of course I knew they weren't but...

People see for yourselves, this is one of the worst DR meter results if not the worst, I've seen:

CODE

foobar2000 1.1.11 / Dynamic Range Meter 1.1.1
log date: 2012-03-29 05:47:45

--------------------------------------------------------------------------------
Analyzed: The Mars Volta / Noctourniquet
--------------------------------------------------------------------------------

DR         Peak         RMS     Duration Track
--------------------------------------------------------------------------------
DR4       -0.20 dB    -6.74 dB      4:49 01-The Whip Hand
DR5        0.00 dB    -6.04 dB      5:11 02-Aegis
DR3        0.00 dB    -3.91 dB      4:22 03-Dyslexicon
DR2        0.00 dB    -4.44 dB      6:43 04-Empty Vessels Make the Loudest Sound
DR3        0.00 dB    -4.90 dB      4:44 05-The Malkin Jewel
DR3        0.00 dB    -4.95 dB      4:16 06-Lapochka
DR4        0.00 dB    -6.11 dB      7:26 07-In Absentia
DR3        0.00 dB    -5.51 dB      3:58 08-Imago
DR3        0.00 dB    -4.53 dB      3:33 09-Molochwalker
DR4        0.00 dB    -7.72 dB      4:25 10-Trinkets Pale of Moon
DR3        0.00 dB    -4.94 dB      3:54 11-Vedamalady
DR4        0.00 dB    -6.38 dB      5:39 12-Noctourniquet
DR3        0.00 dB    -5.75 dB      5:36 13-Zed and Two Naughts
--------------------------------------------------------------------------------

Number of tracks:  13
Official DR value: DR3

Samplerate:        44100 Hz
Channels:          2
Bits per sample:   16
Bitrate:           1003 kbps
Codec:             WavPack
================================================================================

Mastered for iTunes my ass, that's like putting a cherry on top of a pile of shit.

PS: The Dynamic Range Meter results for Ms. Kadry's latest work are worse than Frances the Mute (DR7), Amputechture (DR6) and The Bedlam in Goliath (DR6).


This post has been edited by Fandango: Mar 29 2012, 05:23

[greynol]

I read the paper by Apple back when we first discussed it. I don't believe it said anything about "a healthy dose of additive EQ to restore frequencies that are lost during the AAC conversion process," or did it?

To me this sounds like the author doesn't understand even the basics about how lossy compression works.

EDIT: I read the paper again. It says nothing about additive EQ to restore frequencies that are lost during the AAC conversion process. Not a big surprise.

This post has been edited by greynol: Mar 29 2012, 05:42

[Fandango]

Ah, it has been discussed before and Apple actually released a paper about it? I didn't know that. But yes, regarding the article, I got the same impression, you don't even have to be an expert in the matter to notice that he isn't actually explaining how this technique by Apple works. It's not well written and the fact that one mastering engineers is linking to it, let's one believe that she doesn't have a clue of what she is doing.

[greynol]

I provided a link already. Go to the first post in that topic for a link to the paper.

[Fandango]

I provided a link already. Go to the first post in that topic for a link to the paper.

Thanks, I'm skimming throught it already...

You’re being provided with all the tools you’ll need to encode your masters precisely the same way the iTunes Store does so that you can audition exactly what they’ll sound like as iTunes Plus AAC files.

I have the feeling that this will not end well! The article from the first post here provides proof of that. MEs are tweaking already.

This post has been edited by Fandango: Mar 29 2012, 05:52

[saratoga]

I think the most damning thing about the mastered for itunes program is the incredible detail Apple felt they needed to go into in order to explain how to correctly master tracks so that they do not clip. They explain what clipping is, how it happens, and why someone would want to avoid it. Then they give tools to check for clipping, and urge people to convert their files to lossy first, check for clipping, and then lower the damn volume if it clipped. Finally, they remind people that Apple products use soundcheck, so trying to make their tracks louder digitally will generally not have the intended effect.

Essentially the entire document assumes that the reader has absolutely no idea how to master a CD, and if left to their own devices, they would screw it up. It certainly seems to me at least that Apple's engineers have independently come to much of the same conclusions as the people in this thread, and are at least trying to do something about it.

This post has been edited by saratoga: Mar 29 2012, 05:54

[greynol]

As I said in the dedicated discussion, Apple is addressing inter-sample overs. They were very clear that DRC is subject to artistic expression.

Please, let's not have a parallel discussion about this here.

EDIT: Apple is addressing clipping resulting from lossy compression. I'm brain-dead this evening.

This post has been edited by greynol: Mar 29 2012, 06:43