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

[julf]

Except psychoacoustically, small differences in 'volume' are not necessarily perceived as 'loudness' changes -- they are perceived as quality changes. That's why the biasing effect of level mismatch is so insidious.

Absolutely. When I did a rudimentary 16-bit vs 24-bit and 44 vs 48 vs 96 k listening test over at CA, one of my references was a file that had been amplified by 1 dB. That was the one consistently picked as "best" despite not being the best sample rate or resolution...

[ErectX]

Engineers really need to go back to the pre-mastered version and use this for a quality lossy encode.

Mastering these days is a euphemism for making the tracks as hot as possible. This means not just using typical analog-style dynamic compression to get it as close to 0dB as possible, they use digital processing on the waveform samples to essentially clip (with rounded edges) every peak to make a CD packed full of maximum level samples. You can see this when viewing the waveform on a ripped CD of something new, you would swear the signal is just clipped from the multiple max samples in a row. Even just decoding the samples back into a analog waveform (with DAC lowpass frequency filtering) will result in levels higher than 0dB. That's how you get a CD that looks like this: http://upload.wikimedia.org/wikipedia/comm...se_waveform.png

Another factor turning 0dB meant-for-CD tracks into a clipped mess is that when encoding lossy, the audio content is filtered into many passbands, and the ones deemed to be inaudible are discarded. Changing the spectral content will result in a 0dB signal going above 0dB too, as frequency components that had previously cancelled each other out are removed. One has to encode and then decode to see the resultant levels above peaks, and then process them into analog VU levels beyond that to avoid DAC clipping of the analog waveform. In other words, encode audio that gets nowhere near 0dB.

Then finally there is the fact that the psychoacoustic model can't work well on audio cranked up way beyond max. Lossy compression works on figuring out what you can't hear and discarding it, in comparison to a reference level. When the RMS level of the signal is +20dB of what an uncompressed and unprocessed version would be, lossy codecs can no longer work well as it will not be played back anything like the codec hearing model unless you like jet-engine volumes.

There is no reason to encode mp3/aac at loudness war levels. The audio is not going to be played on radio and doesn't have to compete with other tracks in the "loudness" war. The problem is that to do a proper "mastering for iTunes", you have to go back to the source before it went through the bit-cranking hard limiters, and it is doubtful that many engineers will be paid to do this. And unfortunately, "mastered for iTunes" more likely means that misguided engineers actually compress the audio more and screw with the equalization, picturing cheap speakers and ipods as the destination.

This post has been edited by ErectX: Apr 13 2012, 17:31

[Thasp]

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.

He was trying to be informative. Is it really necessary that he denote everything he says with "I already knew this, but just incase YOU didn't.."

When you are trying to get people to listen to you - you should not be condescending. This is a social industry, you get nowhere by giving people the "wow, you didn't already know X? Well, here's what you SHOULD know" attitude.

Most mastering engineers hate what they are forced to do by the labels. They do it because if they don't, someone else with an L2 or Ozone maximizer plugin. Mastering engineers crushing music sucks, but it is 100000x worse when some bozo with a single plugin tries to do the same thing.

It is weird that in 2013 we are still reading threads where people blame the mastering engineers for everything. If mastering dude X doesn't ruin the music, he will be fired and they will give it to mastering guy Y. Considering how few paying jobs there are left in the music industry, you can't expect them to abandon their paying clients to fight a losing battle when the crushing will happen down the hall at another studio anyway.

This post has been edited by Thasp: Yesterday, 06:20

[Kohlrabi]

Most mastering engineers hate what they are forced to do by the labels. They do it because if they don't, someone else with an L2 or Ozone maximizer plugin. Mastering engineers crushing music sucks, but it is 100000x worse when some bozo with a single plugin tries to do the same thing.

You can make a recording sound hot without showing off your technical inability by letting your signal clip or claiming FUD about AAC. I simply don't buy the "poor mastering engineers" story in these cases. How come that regardless of producer the same engineers always produce the same horrible masters?

It is weird that in 2013 we are still reading threads where people blame the mastering engineers for everything. If mastering dude X doesn't ruin the music, he will be fired and they will give it to mastering guy Y. Considering how few paying jobs there are left in the music industry, you can't expect them to abandon their paying clients to fight a losing battle when the crushing will happen down the hall at another studio anyway.

So, we should all be thankful for the great job Vlado Meller did on the last few RHCP recordings, because someone else might have done a worse job? That's a pretty low standard there.

[2Bdecided]

He was trying to be informative.

If that's informative, it just shows you how behind the times the audience is.

FWIW some (lesser) mastering engineers absolutely despise discussions like this. Their results aren't shameful to them - they are quite proud of what they do, and are very insulted that anyone should question their "judgement" and "skill". It's the good ones that realise what crap they're pushing out.

We should remember that, even in 2013, there are still whole swathes of the industry that are largely unaffected by these trends - with many wonderful recordings issued every year.

Cheers,
David.

[Kohlrabi]

We should remember that, even in 2013, there are still whole swathes of the industry that are largely unaffected by these trends - with many wonderful recordings issued every year.

Which is problematic if you are into pop, rock or metal music (and derivatives), since the mastering standards in these genres are generally exceptionally low.

This post has been edited by Kohlrabi: Yesterday, 10:23

[db1989]

To add to the recent unearthing of this post:

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?!

Not to mention that his oversimplified statement implies that such introduced clipping is more likely to be audible/consequential than it is in reality.

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.

Indeed. Many of us had the same sentiment in the thread about this, erm, service. Something is fundamentally wrong with the concept. Another amazing innovation from Apple!

[skamp]

Not to mention that his oversimplified statement implies that such introduced clipping is more likely to be audible/consequential than it is in reality.

I recall that you retorted to me in the past, that I jumped the gun by drawing conclusions from certain statements. This time I think it applies to you. Simply saying that some processing can cause clipping doesn't imply anything about audibility, just like it doesn't imply anything about the amount of clipping that will occur. And as a techie who likes to do things Right™, you're probably going to aim for a result that doesn't include any clipping at all, even if SOME of it would be acceptable (inaudible). But then that only implies attenuation (or headroom), in the smallest amount that will do the job.

Indeed. Many of us had the same sentiment in the thread about this, erm, service. Something is fundamentally wrong with the concept. Another amazing innovation from Apple!

I don't recall Apple's paper saying anything about applying EQing or any other sort of processing prior to encoding. The important part of it was, "please feed our encoder your high resolution master without prior downsampling, as our encoder will do it automatically with optimized settings" (I'm paraphrasing here). The idea that a different master is needed, more likely comes from mastering engineers like Vlado Meller (and producers like Rick Rubin) trying to get more business.

This post has been edited by skamp: Yesterday, 14:29

[db1989]

I recall that you retorted to me in the past, that I jumped the gun by drawing conclusions from certain statements. This time I think it applies to you. Simply saying that some processing can cause clipping doesn't imply anything about audibility, just like it doesn't imply anything about the amount of clipping that will occur.

This is a good point. I should have qualified my statement with the condition that what he said was technically correct. What I meant was that it might be open to being misread by other people. But that is their problem, not his, and it is probably not very feasible to expect people always to bullet-proof their statements against misinterpretation by others.

And as a techie who likes to do things Right™, you're probably going to aim for a result that doesn't include any clipping at all, even if SOME of it would be acceptable (inaudible).

This is a nice thought, if only it were true for more engineers!

I don't recall Apple's paper saying anything about applying EQing or any other sort of processing prior to encoding. The important part of it was, "please feed our encoder your high resolution master without prior downsampling, as our encoder will do it automatically with optimized settings" (I'm paraphrasing here). The idea that a different master is needed, more likely comes from mastering engineers like Vlado Meller (and producers like Rick Rubin) trying to get more business.

Good points too. I confess that I remembered little about MfI, and not to blame David, but when I read what he said, I just defaulted to assuming it was definitely correct.

Still, looking at the official PDF about MfI, certainly not all of it is unreasonable, but very near the start, we have this:

AAC is the new standard for digital music. It only makes sense to create masters specifically for this format.

As the document goes on to explain, albeit without making it crystal-clear and thus avoiding the risk of undermining their pet format, the concepts recommended by Apple during mastering are not format-specific and, indeed, are little more than common sense. Whilst I cannot argue with many of their recommendations on the latter level, I disagree with how they are presented as revelations and points in favour of AAC. Anyway, no doubt this has all been said before.

[smok3]

From what I observed lately mastering goes all the way from useless to quite ok, however there is that weird feeling when you enjoy youtube-bootleg version better than the final master.