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Big-label mastering engineers donít understand lossy formats, Article about Mastered for iTunes
Fandango
post Mar 29 2012, 06:04
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QUOTE (saratoga @ Mar 29 2012, 06:53) *
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.

Well, they don't have a clue or why else would they do what they do and say what they say since the age the CD arrived? Wasn't Apple too trustful of what the engineers eventually will do with this Mastered for iTunes concept and the provided tools?

From the article by Mr. Coletti it seems some mastering engineers already interpret the concept of Mastering for iTunes their own way and find quite amusing ways to "cheat" the AAC encoder. I'd love to hear what codec developers at Apple have to tell about their cooperation with those guys. But that must remain behind NDA-secured corporate walls, I guess.
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saratoga
post Mar 29 2012, 06:12
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QUOTE (greynol @ Mar 29 2012, 00:59) *
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.


Yes of course, and I'm not interested in that argument. I'm just pointing out their presumed level of reader competence:

QUOTE
Clipping is a form of audio distortion
and can be caused in many ways. In
general, it is the result of the amplitude
of a signal becoming too great to be
accurately represented by a system.


Can you imagine if FAA flight regulations began like this?

"Plane crashes are a form of impacting the ground at high speed. Plane crashes can be caused in many ways. In general, they are the result of the plane descending too fast..."

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greynol
post Mar 29 2012, 06:30
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laugh.gif


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2Bdecided
post Mar 29 2012, 09:36
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It's what happens when the art-world and science/engineering-world meet head-on. You get arty people operating technical equipment, when their understanding is barely one step up from believing that magic pixies are making it all work.

Actually, some of them probably do believe in the magic pixies.


It would probably be even worse if we only got to hear songs written by artless science types*. Good songs, badly recorded, vs bad songs perfectly recorded? wink.gif

* - I can upload something I wrote to prove the point. wink.gif

Cheers,
David.
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TrustScience
post Mar 29 2012, 14:24
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QUOTE (Canar @ Mar 28 2012, 21:12) *
QUOTE (TrustScience @ Mar 28 2012, 15:39) *
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.

Haha - Fair enough.

QUOTE (saratoga @ Mar 28 2012, 22:29) *
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.


Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.

QUOTE (saratoga @ Mar 28 2012, 22:29) *
First everything that clown (Shepherd) says is irrelevant since you can't show that one encoding is closer to CD by subtraction. [/b] 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"?


What you seem to take issue with here is that I presented the most damning argument last rather than first (because that's how mounting arguments work!) Otherwise, I think we're on the same page. smile.gif

Shepherd's faulty analysis was ranked high in Google and getting a ton of reads, so I felt it was only appropriate to address it in the article. Please remember that not everyone has the same level of understanding, and that a nuanced breakdown is extremely valuable to many readers.


QUOTE (greynol @ Mar 28 2012, 23:23) *
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?
...
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.


Correct greynol, that fact is not from the Apple paper, but from my interviews with over a half dozen of the busiest M.E.s in New York City.

They say that in practice, they use the new toolset to A/B before-and-after files, and then use additive EQ to compensate for changes in tone if they find it necessary to do so.

In theory, that's not much different than having two slightly different EQ settings so that a cassette and vinyl version sound closer.

Many of you might effectively argue that this process is subjective and open to error (true) or that the sonic differences between a 24-bit WAV and a 256kbps AAC tend to be much slighter than the differences between vinyl and cassette (also true).


QUOTE (Fandango @ Mar 28 2012, 23:14) *
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).


To be fair, I believe that's a reflection of taste rather than competence. Making a master that's less hot isn't that difficult, and it doesn't take much advanced training at all.

To argue that Kadry or any other in-demand ME don't know what they're doing misses the point. I believe they know exactly what they're doing: Making very loud masters!

Whether you dig what they're doing is an entirely different question. I just don't think it makes sense to argue about that on a "technical" level.

(Unless you we were citing some scientific double-blind tests that compare specific levels of dynamic range with perceived enjoyment. Now that would be neat! If you know of such a study, I'd be the first to read it.)

I'll admit that I haven't heard the records you've cited here, but in defense of Kadry, it's important to remember that any mastering job can be deemed "good" as long as it's what it was intended to be. We just have to judge it by the creator's criteria.

For instance: I love the sound of a lot of Dave Fridmann's work with the Flaming Lips, which is often clipped-to-death. What's important to remember is that those records aren't clipped because they're loud... they're loud because they're clipped!

That's a world of difference. That style of mixing and mastering is an aesthetic choice, and not some unintended side-effect of ignorance or accident.

The truth is that mastering engineers who get repeat clients aren't making loud records by mistake. You don't have to like their work, but I still think it's important to make a fair argument. Otherwise, we just end up sounding like dimwits who trash on studio reverbs because they don't sound like actual concert halls.

It's also useful to remember that to people younger than us, taste-based arguments against hot, bombastic masters is going to sound a whole lot like "Hey you damn kids, get off of my lawn!"

In reality, that's part of the reason the kids are into those records in the first place! Don't you remember what it's like to be young? cool.gif What self-respecting American teenager wants to listen exclusively to music his parents would approve of?

In the end, I think that with the right effort, we can bring healthy dynamic range back into the mainstream. I just don't think we're going to do that by making negative or unprincipled arguments.

QUOTE (2Bdecided @ Mar 29 2012, 03:36) *
It's what happens when the art-world and science/engineering-world meet head-on.
...
It would probably be even worse if we only got to hear songs written by artless science types*. Good songs, badly recorded, vs bad songs perfectly recorded? wink.gif


Now that, I'd agree with in a heartbeat.

This post has been edited by TrustScience: Mar 29 2012, 15:16
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greynol
post Mar 29 2012, 15:22
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QUOTE (TrustScience @ Mar 29 2012, 06:24) *
QUOTE (greynol @ Mar 28 2012, 23:23) *
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?
...
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.

Correct greynol, that fact is not from the Apple paper, but from my interviews with over a half dozen of the busiest M.E.s in New York City.

Your article states that the Mastered for iTunes process adds EQ to compensate for losses caused by the encoding process. It should say that some mastering specialists are taking a liberty that is not prescribed by the process.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
They say that in practice, they use the new toolset to A/B before-and-after files, and then use additive EQ to compensate for changes in tone if they find it necessary to do so.

So that you understand, Justin, A/B is not ABX. If these specialists were to actually employ ABX then they would quickly realize that the compression process does not color the tone in the way that they imagine.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
In theory, that's not much different than having two slightly different EQ settings so that a cassette and vinyl version sound closer.

It would be if the compression process actually colored the tone.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Many of you might effectively argue that this process is subjective and open to error (true)

Subjective in that some people are more capable of identifying lossy artifacts than others? Yes. Subjective in that expectation bias cannot be circumvented? No.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
that the sonic differences between a 24-bit WAV and a 256kbps AAC tend to be much slighter than the differences between vinyl and cassette (also true).

Yes, but the type of audible lossy artifacts cannot be corrected through pre-equalization. To think otherwise is foolhardy.


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greynol
post Mar 29 2012, 15:37
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QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.

I don't think Saratoga will mind me speaking to this. The issue is not peak levels, the issue is audible distortion that is caused by aggressive use of dynamic range compression. Reducing the volume by a "full" decibel below full-scale does very little to cool a hot master.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
For instance: I love the sound of a lot of Dave Fridmann's work with the Flaming Lips, which is often clipped-to-death. What's important to remember is that those records aren't clipped because they're loud... they're loud because they're clipped!

They're loud because they're compressed (and sometimes given mid-range emphasis) and often this compression can cause clipping regardless of whether the final master reaches full-scale.

QUOTE (TrustScience @ Mar 29 2012, 06:24) *
That's a world of difference.

Yes, especially when you actually focus on the offending mechanism. wink.gif

You might find this educational:
http://www.hydrogenaudio.org/forums/index....showtopic=91909

This post has been edited by greynol: Mar 29 2012, 15:53


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2Bdecided
post Mar 29 2012, 16:45
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QUOTE (TrustScience @ Mar 29 2012, 13:24) *
That style of mixing and mastering is an aesthetic choice, and not some unintended side-effect of ignorance or accident.

The truth is that mastering engineers who get repeat clients aren't making loud records by mistake. You don't have to like their work, but I still think it's important to make a fair argument. Otherwise, we just end up sounding like dimwits who trash on studio reverbs because they don't sound like actual concert halls.

It's also useful to remember that to people younger than us, taste-based arguments against hot, bombastic masters is going to sound a whole lot like "Hey you damn kids, get off of my lawn!"

In reality, that's part of the reason the kids are into those records in the first place!
You can have that sound without clipping. What you can't have is that loudness. If you switch Sound Check on, or use ReplayGain, the latter is irrelevant.

Some clipping is inaudible. Some clipping is gratuitously audible, and sounds like ****. Teenagers might like a loud aggressive sound, but when they grow up and try to play their music on something other than a mobile phone, they'll find the clipped bass just sounds poor. Or maybe, as CliveB suggests in that thread greynol just linked to, people will give up trying to play recent pop music on decent stereos because it just sounds so bad. I know I have. I save it for the car/train.


I think there's a big distinction between intentionally changing the sound to make the whole recording sound more dense, and trying to make the master louder while trying not to change the sound too much. Others will disagree, but it's the latter that I think is a disaster. You have a recording, it sounds just how you want it to - but then you wreck it to make it louder. That's pathetic. Whereas taking a recording which doesn't sound how you want it to, and trashing it to make it sound like you want it to is another matter entirely!

Cheers,
David.

EDIT: You can change the sound of something without clipping it at all, or even making it louder. Here's a jazz example...
original:
Attached File  04_Claire_Martin___Chased_Out_section_2.mp3 ( 356.31K ) Number of downloads: 180

compressed:
Attached File  04_Claire_Martin___Chased_Out_section_DRC2_EQ_16_bit.mp3 ( 354.22K ) Number of downloads: 171

I'm sure someone with access to a proper compressor and some unmastered pop music could prove the point better.

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krabapple
post Mar 29 2012, 17:10
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QUOTE (TrustScience @ Mar 29 2012, 09:24) *
For instance: I love the sound of a lot of Dave Fridmann's work with the Flaming Lips, which is often clipped-to-death. What's important to remember is that those records aren't clipped because they're loud... they're loud because they're clipped!
.
.
.
It's also useful to remember that to people younger than us, taste-based arguments against hot, bombastic masters is going to sound a whole lot like "Hey you damn kids, get off of my lawn!"



Wayne Coyne is just one year younger than me. Given the kind of mastering he favors, I've got to wonder how good his hearing is at this point. wink.gif


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krabapple
post Mar 29 2012, 17:14
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QUOTE (greynol @ Mar 29 2012, 10:22) *
So that you understand, Justin, A/B is not ABX. If these specialists were to actually employ ABX then they would quickly realize that the compression process does not color the tone in the way that they imagine.
...

It would be if the compression process actually colored the tone.



You mean 'data compression' (high bitrate lossy encoding in this case) here rather than dynamic range compression, right? The latter certainly can subjectively 'color the tone'.

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krabapple
post Mar 29 2012, 17:17
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QUOTE (greynol @ Mar 29 2012, 10:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.

I don't think Saratoga will mind me speaking to this. The issue is not peak levels, the issue is audible distortion that is caused by aggressive use of dynamic range compression. Reducing the volume by a "full" decibel below full-scale does very little to cool a hot master.


Not to mention that individual tracks of a multitrack can already be made 'hot' early in the production process -- nothing done at the mastering stage can reverse that.

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TrustScience
post Mar 29 2012, 17:18
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QUOTE (greynol @ Mar 29 2012, 09:22) *
Your article states that the Mastered for iTunes process adds EQ to compensate for losses caused by the encoding process. It should say that some mastering specialists are taking a liberty that is not prescribed by the process.


As a matter of practice, the engineers I spoke to employ the judicious use of EQ as part of the process. You're entitled to your argument, although I feel it's a semantic one. I still think the way it was expressed in the article gives the clearest picture of what engineers are actually doing. Of course, you don't have to agree!

QUOTE (greynol @ Mar 29 2012, 09:22) *
So that you understand, Justin, A/B is not ABX. If these specialists were to actually employ ABX then they would quickly realize that the compression process does not color the tone in the way that they imagine.


I'm aware that A/B and ABX are different, and I believe any credible mastering engineer would be as well. The M.E.s I spoke to are arguing that faults in the encoding process have resulted in audible tonal differences in the resulting files in many cases. Whether you believe that claim is another story.

As you already know, listening tests suggest that with proper encodes at a decent rate, this shouldn't be the case for almost any listeners. This fact is also mentioned in the story, complete with a link to an entire article on the importance of blind listening tests. I felt that was a responsible thing to do.

QUOTE (greynol @ Mar 29 2012, 09:22) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
In theory, that's not much different than having two slightly different EQ settings so that a cassette and vinyl version sound closer.

It would be if the compression process actually colored the tone.


See above.

QUOTE (greynol @ Mar 29 2012, 09:22) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Many of you might effectively argue that this process is subjective and open to error (true)

Subjective in that some people are more capable of identifying lossy artifacts than others? Yes. Subjective in that expectation bias cannot be circumvented? No.


Agreed.

QUOTE (greynol @ Mar 29 2012, 09:22) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
that the sonic differences between a 24-bit WAV and a 256kbps AAC tend to be much slighter than the differences between vinyl and cassette (also true).

Yes, but the type of audible lossy artifacts cannot be corrected through pre-equalization. To think otherwise is foolhardy.


Again, the mastering engineers are claiming that there were tonal differences between the resulting AACs and the 24-bit source file that are separate from what we consider expected lossy artifacts.

They also claimed that creating a different master for the encoder was able to lessen the tonal differences between files, and have stated that the iTunes Store's encoding process has been improved as part of "Mastered for iTunes."

Again, I have no way to prove or disprove these claims. I am only able to present them as consistent statements, and to allow room for skepticism, and suggest further reading to give fuller context. To take a different stance would have been dishonest and biased. The rest is for you guys to test and decide! If you come up with a scientific and newsworthy conclusion, then I can always report on that too.
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TrustScience
post Mar 29 2012, 17:32
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QUOTE (greynol @ Mar 29 2012, 09:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.

I don't think Saratoga will mind me speaking to this. The issue is not peak levels, the issue is audible distortion that is caused by aggressive use of dynamic range compression. Reducing the volume by a "full" decibel below full-scale does very little to cool a hot master.


I'm sorry greynol, but I think you're confused about Ludwig's point here. From what I understand, he suggests that lowering the peak level reduces the number of additional clipping errors introduced by the AAC encoder itself. According to his argument, and the Apple whitepaper, this is a separate issue from aggressive use of dynamic range compression.

QUOTE (greynol @ Mar 29 2012, 09:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
For instance: I love the sound of a lot of Dave Fridmann's work with the Flaming Lips, which is often clipped-to-death. What's important to remember is that those records aren't clipped because they're loud... they're loud because they're clipped!

They're loud because they're compressed (and sometimes given mid-range emphasis) and often this compression can cause clipping regardless of whether the final master reaches full-scale.


Compression is clipping - In a very strict and literal sense. Whenever a compressor or limiter acts on peaks, it is inducing "clipping" by definition.

QUOTE (greynol @ Mar 29 2012, 09:37) *


I've read Bob Katz's book a couple of times and seen him speak on several occasions. I don't have the time to check out another of his videos at the moment, but maybe later.

If your desire is to school me on the basics of how all this works, there may be better uses of your time. But if you honestly think it's a neat video that adds something new to the conversation, I'd love to check it out in the future!

Have a good one,

Justin

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greynol
post Mar 29 2012, 17:39
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QUOTE (TrustScience @ Mar 29 2012, 09:18) *
As a matter of practice, the engineers I spoke to employ the judicious use of EQ as part of the process. You're entitled to your argument, although I feel it's a semantic one.

Your negligence is appalling! You are clearly misleading people into believing that judicious use of EQ is part of Apple's process. It is not.

QUOTE (TrustScience @ Mar 29 2012, 09:32) *
I'm sorry greynol, but I think you're getting confused about Ludwig's point here. He suggests that lowering the peak level reduces the number of additional clipping errors introduced by the AAC encoder. According to his argument, and the Apple whitepaper, this is a separate issue from aggressive use of dynamic range compression.

Once again, I think you should be concerned with your communication. It was about Saratoga's point, not your non sequitur reply.

QUOTE (TrustScience @ Mar 29 2012, 09:32) *
Of course, if you honestly think it's a neat video that adds something new to the conversation, I'd love to check it out!

I do.

QUOTE (TrustScience @ Mar 29 2012, 09:32) *
I think it should be clear by now that there may be better uses of your time.

This is disappointing as you don't really inspire much confidence if you think compression and clipping are the same thing.

This post has been edited by greynol: Mar 29 2012, 17:57


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saratoga
post Mar 29 2012, 17:48
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QUOTE (TrustScience @ Mar 29 2012, 09:24) *
QUOTE (saratoga @ Mar 28 2012, 22:29) *
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.


Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are.


I'm not talking about intentions, I'm talking about competence. Its great if he dislikes how hot things are mastered and I completely agree with him if so. My general complaint is that you make it sound like he has no idea why clipping happens smile.gif

QUOTE (TrustScience @ Mar 29 2012, 09:24) *
Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.


If by 'handle' you mean 'not clip' then this would be basically impossible. So either they don't know what they're doing, or they're just leaving clipping in for basically no reason!

QUOTE (TrustScience @ Mar 29 2012, 09:24) *
Again, the mastering engineers are claiming that there were tonal differences between the resulting AACs and the 24-bit source file that are separate from what we consider expected lossy artifacts.


If someone tells you this, then you ought to know that they are not credible.

QUOTE (TrustScience @ Mar 29 2012, 09:24) *
Again, I have no way to prove or disprove these claims. I am only able to present them as consistent statements, and to allow room for skepticism, and suggest further reading to give fuller context.


There is actually a lot of research into the artifacts produced by perceptual audio encoding. Saying you have no way to verify a statement here is incorrect. You could access the research in question, compare files yourself, or use your knowledge of how perceptual audio encoding works to realize that you're being fed a load of bullshit.

So saying you have no way to prove or disprove these claims is simply not true. I think what you mean to say is that you decided not to try and evaluate these claims. Which is unfortunate, because they are counter to the reality of how AAC encoding works.
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TrustScience
post Mar 29 2012, 17:49
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QUOTE (greynol @ Mar 29 2012, 11:39) *
QUOTE (TrustScience @ Mar 29 2012, 09:18) *
As a matter of practice, the engineers I spoke to employ the judicious use of EQ as part of the process. You're entitled to your argument, although I feel it's a semantic one.

Your negligence is appalling! You are clearly misleading people into believing that judicious use of EQ is part of Apple's process. It is not.


I have to disagree. I believe that yours is an extreme statement, as well as a misinterpretation of the whitepaper.

Apple has released new tools, based on the engineer's requests, that were specifically designed to allow them to A/B the source and encoded material and make adjustments if necessary.

It's true that Apple's documentation does not say "Though Must EQ", but to call a reasonably accurate representation of the practice and the context that surrounding "misleading" or "negligent" is ridiculous.

With that, I'm going to have to bow out of this conversation, as your demeanor is clearly inhospitable, and you're now resorting to knee-jerk ad hominem attacks.

Sorry dude. Not my style. The floor is now yours, and you can use it to be a silly and self-important as you want.

Bye now,

Justin
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saratoga
post Mar 29 2012, 18:00
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QUOTE (TrustScience @ Mar 29 2012, 12:32) *
QUOTE (greynol @ Mar 29 2012, 09:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.

I don't think Saratoga will mind me speaking to this. The issue is not peak levels, the issue is audible distortion that is caused by aggressive use of dynamic range compression. Reducing the volume by a "full" decibel below full-scale does very little to cool a hot master.


I'm sorry greynol, but I think you're confused about Ludwig's point here. From what I understand, he suggests that lowering the peak level reduces the number of additional clipping errors introduced by the AAC encoder itself.


He "suggests" that taking a signal thats just short of peak normalized and then adding a bunch of additional random signals to it might introduce clipping? Are you sure he is only suggesting that taking a signal and driving it above peak will introduce clipping?

Would you "suggest" 1+1=2? smile.gif

QUOTE (TrustScience @ Mar 29 2012, 12:32) *
QUOTE (greynol @ Mar 29 2012, 09:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
For instance: I love the sound of a lot of Dave Fridmann's work with the Flaming Lips, which is often clipped-to-death. What's important to remember is that those records aren't clipped because they're loud... they're loud because they're clipped!

They're loud because they're compressed (and sometimes given mid-range emphasis) and often this compression can cause clipping regardless of whether the final master reaches full-scale.


Compression is clipping - In a very strict and literal sense. Whenever a compressor or limiter acts on peaks, it is inducing "clipping" by definition.


No this is nonsense.

QUOTE (TrustScience @ Mar 29 2012, 12:32) *
I have to disagree. I believe that yours is an extreme statement, as well as a misinterpretation of the whitepaper.

Apple has released new tools, based on the engineer's requests, that were specifically designed to allow them to A/B the source and encoded material and make adjustments if necessary.


Yes, but the claims you have made are as far as I can tell, so while his statement may be extreme, it also appears to be correct.

QUOTE (TrustScience @ Mar 29 2012, 12:32) *
With that, I'm going to have to bow out of this conversation, as your demeanor is clearly inhospitable, and you're now resorting to knee-jerk ad hominem attacks.


Attacking the false statements you make is not an ad hominem attack. An ad hominem attack is an argument of the form "you're wrong because you're stupid". Arguments that begin with "you've made incorrect statements, therefore..." are not ad hominem by definition, even if you feel attacked by them.


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saratoga
post Mar 29 2012, 18:02
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QUOTE (TrustScience @ Mar 29 2012, 12:49) *
With that, I'm going to have to bow out of this conversation, as your demeanor is clearly inhospitable, and you're now resorting to knee-jerk ad hominem attacks.

Sorry dude. Not my style. The floor is now yours, and you can use it to be a silly and self-important as you want.


Ironically, this IS an ad hominem attack!
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TrustScience
post Mar 29 2012, 18:02
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QUOTE (saratoga @ Mar 29 2012, 11:48) *
There is actually a lot of research into the artifacts produced by perceptual audio encoding.
...
So saying you have no way to prove or disprove these claims is simply not true.


That is a fair argument, saratoga. Still, I have to remind you that I don't have access to their before and after files, and therefore it would be patently wrong of me to say that dozens of respected audio professionals are lying without having actual direct evidence.

All I can do is remind readers that there have been a ton of listening tests and studies that suggest it's unlikely any listeners would be able to hear tonal differences between these files, if they do in fact exist.

The article was also supportive of skepticism against these claims, but maintained that those accusations should be made properly. And again, I even wrote and linked to an article supporting blind ABX listening tests that would encourage healthy skepticism.

I think that's due diligence. You're entitled to feel like I should have taken a harder line in support of your position. However, I believe my job here was to present the news, the process, and the context surrounding it. My job was not to editorialize passionately that it's a foregone conclusion that mastering engineers must be lying dirtbags because related tests raise suspicions on their claims! smile.gif So, mission accomplished, I guess.

Again, I see the atmosphere here has become less than welcoming of a nuanced and non-aggressive position like mine, so I'm going to respectfully step aside, and leave you guys to it.

This post has been edited by TrustScience: Mar 29 2012, 18:19
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greynol
post Mar 29 2012, 18:03
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QUOTE (krabapple @ Mar 29 2012, 09:14) *
You mean 'data compression' (high bitrate lossy encoding in this case) here rather than dynamic range compression, right?

Right.

This post has been edited by greynol: Mar 29 2012, 18:44


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saratoga
post Mar 29 2012, 18:13
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QUOTE (TrustScience @ Mar 29 2012, 13:02) *
QUOTE (saratoga @ Mar 29 2012, 11:48) *
There is actually a lot of research into the artifacts produced by perceptual audio encoding.
...
So saying you have no way to prove or disprove these claims is simply not true.


That is a fair argument, saratoga. Still, I have to remind you that I don't have access to their before and after files, and therefore it would be patently wrong of me to say that dozens of respected audio professionals are lying without having actual direct evidence.


They're not lying, they're confused. And no its not wrong of you to figure out whats going on. You call yourself a journalist right? Isn't that actually your job, to know whats going on and then report it? If you just report what someone says without actually figuring out if they understand what they're saying, you're not doing a very good job.

QUOTE (TrustScience @ Mar 29 2012, 13:02) *
All I can do is remind readers that there have been a ton of listening tests and studies that suggest it's unlikely any listeners would be able to hear tonal differences between these files, if they do in fact exist.


But you didn't even do that much!

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

You're repeating something that you know isn't true! Why?

QUOTE (TrustScience @ Mar 29 2012, 13:02) *
I believe my job here was to present the news, the process, and the context surrounding it.


So how does repeating things that aren't true work towards that end?

QUOTE (TrustScience @ Mar 29 2012, 13:02) *
Again, I see the atmosphere here has become less than welcoming of a nuanced and non-aggressive position like mine, so I'm going to respectfully step aside, and leave you guys to it.


Heh, I would say lazy and misinformed. And indeed, people won't be welcoming of that. But if we're welcoming of you, well that depends. Are you willing to open your mind and learn something or are you going to get angry and storm off that people don't agree with you?
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saratoga
post Mar 29 2012, 18:19
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QUOTE (greynol @ Mar 29 2012, 10:37) *
QUOTE (TrustScience @ Mar 29 2012, 06:24) *
Hi Saratoga,

I think you and Ludwig would agree that most masters shouldn't be as hot as they are. From what I remember, he's come recommending that masters peak at a maximum of a full -1db below 0dbfs to reduce unintended clipping, which is an idea that was balked at by many of the mastering engineers I spoke with. Most of them seemed to believe their clients expect peaks at at least -0.5 or -0.4 dbfs, and would continue shooting for those peaks as long as they could verify that the encoder could handle it.


I don't think Saratoga will mind me speaking to this. The issue is not peak levels, the issue is audible distortion that is caused by aggressive use of dynamic range compression. Reducing the volume by a "full" decibel below full-scale does very little to cool a hot master.


I think you and I have a different perspective here. I don't mind high dynamic range compression necessarily. What drives me nuts is audible clipping. It just ruins the sound to me. So if someone has a master that sounds good with high compression, I'm ok with that. But I just ask that, having knocked off all the peaks, they don't then push the entire signal up into distortion! Its not that hard to set the level first, then apply DRC. But everyone seems to like to do it the other way and it sounds awful.

People talking about a fraction of a dB of headroom on a DRCed track is just nuts.
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2Bdecided
post Mar 29 2012, 18:26
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QUOTE (TrustScience @ Mar 29 2012, 16:32) *
Compression is clipping - In a very strict and literal sense. Whenever a compressor or limiter acts on peaks, it is inducing "clipping" by definition.
Oh for goodness sake - you haven't a clue what you're talking about with this one!

(there's no nicer way of putting it - sorry!).

Cheers,
David.
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TrustScience
post Mar 29 2012, 18:52
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QUOTE (2Bdecided @ Mar 29 2012, 12:26) *
QUOTE (TrustScience @ Mar 29 2012, 16:32) *
Compression is clipping - In a very strict and literal sense. Whenever a compressor or limiter acts on peaks, it is inducing "clipping" by definition.
Oh for goodness sake - you haven't a clue what you're talking about with this one!

(there's no nicer way of putting it - sorry!).

Cheers,
David.


David, care to back that statement up with a widely accepted definition of "clipping" that would exclude an aggressive dynamic-range limiter? biggrin.gif

To be honest, I'm really surprised and disappointed by the few posters who are taking extreme positions and resorting to anonymous ad hominem attacks, especially when we already agree on so much.

Disagreement I'm fine with. The childishness of a few of your peers, not so much.

For the record, I am ethically and legally obligated not to call anyone "a liar" or "incompetent" without direct proof. That would be called "libel".

There are related studies that can be used to suggest the MEs and Apple folks could be overstating their claims. (The article makes direct mention of that - I'm surprised I have to keep mentioning that like it hasn't been said already.) But without direct before-and-after evidence, saying that their claims are conclusively false would not only be illegal and unethical, but factually incorrect.

That's all I have to say on that. I'm sure the vast majority of readers here are smart enough and unbiased enough to understand that. For the few who aren't - I'm sorry to hear that. Good luck and be well. I wish you a long life of yelling at strangers on the interwebs.
rolleyes.gif

This post has been edited by TrustScience: Mar 29 2012, 19:00
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Canar
post Mar 29 2012, 18:58
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QUOTE (TrustScience @ Mar 29 2012, 10:52) *
care to back that statement up with a widely accepted definition of "clipping" that would exclude an aggressive dynamic-range limiter?
Urf. You don't need a limiter or anything to clip. f(x)=max(x,min(x,1.0),-1.0) on a signal that exceeds [-1,1] will cause clipping where the signal falls outside that interval. This is conceptually identical to working with samples at a certain word-length and dealing with values that fall outside that word length.

This post has been edited by Canar: Mar 29 2012, 19:00


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