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Master Engineer: Apple's "Mastered For iTunes" No Better Than AAC-Encoded Music
New submitter Stowie101 writes "British master engineer Ian Shepherd is ripping Apple's Mastered for iTunes service, saying it is pure marketing hype and isn't different than a standard AAC file in iTunes. Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences. Apple or someone else needs to step it up here and offer some true 'CD quality downloads.'"
You want CD quality downloads? Yeah, magic keyword "FLAC".
Piracy: giving you for free what the market won't since the first bestiality video was filmed.
While I agree that its all bunk, I would be interested in knowing if the two files where bit for bit the same or just sound the same to the listener?
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
Summary is incorrect. Article says that there was a significant difference between the Mastered for iTunes and CD version, while there was no difference between Mastered for iTunes and a standard AAC track.
To test with Red Hot Chili Peppers is rather pointless, I would think - they're one of the most compressed bands there is, probably not using more than the top 4-5 bits out of 16. So yes, it's going to be fairly similar no matter what the format, unless you can get ahold of the sources to the original masters.
Here is the actual relevant part of the article:
I am not an Apple fan, and, actually, dislike the company. However, I wonder if they are truly making claims that are not true or if their claims are simply carefully worded to convey, well, nothing. Apple seems to big and way too self-important to risk the scandal of an outright lie. It reminds me of how they handled the antennae problem with the iPhone. It would be interesting to hear Apple's response but my guess is that they will simply not respond and their fans will be fine with that.
http://www.busyweather.com/
From the /. summary:
Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences.
That'd be a good thing if there were no differences between the CD version and the audio versions. However, what the article actually says is
After his comparison of the three digital music files, Shepherd says there was a sonic difference between the Mastered for iTunes waveform and the CD waveform. He says the Mastered for iTunes and AAC-encoded files didn't reveal any differences, adding that this proves to him Apple's Mastered for iTunes isn't any different than a standard AAC file from Apple's iTunes store.
In other words, the Mastered for iTunes version is basically identical to the standard AAC version, and both are different from the CD version.
GLaDOS for President 2016! "Well here we are again. It's always such a pleasure." -- GLaDOS, 2011
Those wonderful color screens people could put on their TV's to impreove the picture -- you can't get more out of something than you put into it. If the lossy music process has lost data you can't put it back (but you can always convince the gullible that you can!)
Now, buy my Slashdot Post Converter, which placed on your screen turns each of my posts into a fantastic media experience! Zowie!
A feeling of having made the same mistake before: Deja Foobar
Summary says: "Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences." Emphasis Mine. If there were no difference, then this new format sounds great; what's the problem. Oh right, slashdot.
TFA says: "Shepherd says there was a sonic difference between the Mastered for iTunes waveform and the CD waveform."
Ugh.
Put an end to over compressed music and squeaky sub base encoding with WAVE files! Uncompressed WAV files are super, you can make them as big as you like bits and Hz wise! Need 8.1 channels? NO sweat ... that's 4 stereo and 1 mono! Works great with other uncompressed formats too! Compression is for tiny old handheld gadget weenies, to summarize ... :0)
The purpose of existence is to make money.
Most of what's called music sounds like crap in the firs place. Enhancing mastering quality won't do any good anyway.
Or get the LP version of the album :)
It's The Golden Rule: "He who has the gold makes the rules."
The guy running the tests is also implying that Apple takes an off-the-shelf CD (like he did) and uses that as a source for their music, which may OR MAY NOT be true.
This "mastered for itunes" stuff is pointless crap as long as we are still fighting the Loudness War.
The Red Hot Chili Peppers are a particularly bad test case because all of their albums have massive loudness-compression. And the same guy responsible for that travesty has started to do the mastering on recent Metallica albums so their stuff is going to be all suck too.
When information is power, privacy is freedom.
first:
"Mastered for iTunes format with a CD version of the same song, and said there were no differences. "
then
" Apple or someone else needs to step it up here and offer some true 'CD quality downloads."
Isn't no different then the CD version CD quality?
The Kruger Dunning explains most post on
The summary link just goes to a (slow loading) blog post, the actual article being discussed is at:
http://productionadvice.co.uk/mastered-for-itunes-cd-comparison/
And more specifically, the 11 minute youtube video:
http://www.youtube.com/watch?v=kGlQs9xM_zI
I can't agree with Shephard's methodology here. Why is he using RHCP to guide these comparisons? These are notoriously poorly mixed & mastered tracks - repeat offenders in the Loudness Wars debates that consume the audio engineering industry. Start with a record that is mastered to audiophile standards (say, RATM's debut) and then let's see if there's a difference. A piece of shit is going to sound like a piece of shit no matter what. Especially when the original (CD) master has digital clipping...
Further: "No differences" between CD and downloaded quality is a GOOD THING: The "Mastered for iTunse" AAC format is a compressed version of the audio data found on a CD (both are 16 bit, 44.1khz) so no discernible difference would mean that the encoding is transparent, does not result in a loss of dynamic range, and that the auditory masking effect does not leave artifacts.
The Mastered for iTunes tools creates a iTunes Plus file as its output, just check the docs:
http://www.apple.com/itunes/mastered-for-itunes/
From the PDF:
"Master for iTunes Droplet. The Master for iTunes Droplet is a simple, standalone drag-and-drop tool that can be used to quickly and easily encode your masters in iTunes Plus format."
The PDF is a good read for people wanting to publish to the iTunes store with regards to making sure the best audio quality is sent to them and what to watch out for. But the problem with the whole article is the assumption that Mastered for iTunes != iTunes Plus. They are in fact the same thing, so its no wonder that they test out the same. Add to this the potential differences of quality of the original masters before conversion and of course some details will be lost compared to the master or CD, its lossy compression.
Sadly enough Apple is one of the major forces behind the proliferation of very bad music quality. Not sure why with current advances of storage and processing power we should focus on "true CD quality". There are much better alternatives - Sony SACD (1-bit compression, I guess as close to analog as you can get) or at least 192-24 bit. Most of the materials are recorded in much better quality, and it is shame we are facing low quality offerings only. Unless we steal:)
What the hack is difference for the average Joe?? Very simple, many music styles (baroque, folk, jazz, modern classic) just cannot be appreciated without either live listening or high-quality recording. In my humble opinion, this is one of the reasons great number of people don't even know what many of the genres are.
And - no you do not need to spend $$$ to appreciate good recording.
While you are probably right about the RHCP (as well as any other CD released lately) about the gain compression, there is no reason why you still cant do quantitative analysis to see differences between the two different compression schemes when they are decompressed. It would just be a matter of comparing the bytes of decompressed files to the original, never compressed (ie from the CD) data. Compute the variance of the errors in the two different schemes referenced to the CD and the check to see if they are statistically significant. There you go, you have just tested to see if the compression schemes are different.
That being said, you would probably have a better indicator of errors if you did use a source that was not heavily gain compressed before data compression, but that is another debate.
I can't speak for the RHCP tracks, but I downloaded a dozen or so tracks I already have on CD and exist as both FLAC and LAME MP3s on my computer on the day of the announcement to see what the difference is. I could immediately tell a difference with the Master for iTunes tracks, better or worse, I'm not sure yet. They are easy to pick out in A/B testing, the most glaring difference is in the mid-bass area 80-120hz is noticeably boosted in the rock tracks I downloaded.
Stupid Cheap Guitars
agreed. Listen to "a love supreme" and tell me that it doesn't sound amazing. The point of mfi is not just the encoding process. the producer must also increase the quality of the recording significantly for it to be considered for mfi.
Pretty sure the Mastered for iTunes is not trying to rival CD quality, but rather increase the quality of the current AAC rips by using a better source and providing better tools to do so. A better test would have been to compare the original iTunes AAC with the new Mastered for iTunes AAC and compare those to the CD. Hopefully showing that the new rips are closer in waveform than the old.
It's interesting that this sudden focus on compressed music as opposed to uncompressed (iTunes Plus) has cropped up so soon after Steve's demise. IIRC, Steve was a music nut and was always pushing for DRM-free, higher fidelity digital downloads through iTunes. My foil-hat says that this might be an attempt to sell shitty quality music at a higher price. However, it could also ease network burden when streaming audio on the go. That said, one should still have access to high quality, uncompressed music for when you want to pump up the volume on your home system.
RHCP would be great for the purpose. Or Metallica "Death Magnetic" (or whatever the world champion of compression is nowadays):
HOW different though? I am willing to bet that people tested on very good stereo equipment can't tell the difference between a 320k MP3 and redbook audio. With their ears - not with waveform equipment.
And I mean a real blind test, not just playing both and having them claim that one sounds better.
Is CD quality really the holy grail of audio quality? I thought DVD Audio with up to 24-bit bit depth and 192kps sampling rate was supposed to the the best in audio quality - far beyond the human ear's ability to hear.
Or is CD Quality "good enough", even for audio engineers?
Would I rather listen to an uncompressed 96bit 100kHz sampled (made up spec for effect) recording of Justin Beiber or a scratched 78 rpm recording of Leadbelly (for example)?
No fsckin' contest - tech spec wars are for onanists.
"Mastered for iTunes" is just a set of guidelines that ensure that the resulting AAC file is the highest quality possible when encoded directly from a 24-bit master. It's higher quality then most FLACs because they are usually 16-bit, whereas AAC is essentially 24-bit when the source material is 24-bit. In essence, compressing 24-bit audio to 256kbps AAC sounds better then going to 16-bit uncompressed audio.
If you're going to go FLAC, at least make sure that you're getting 24-bit.
No, I will not work for your startup
HOW different though?
He will need additional funding to explore this aspect.
Brilliant marketing! Apple is primarily a marketing company, so branding specific digital downloads as "Mastered for iTunes" is really smart. As with their other products, that "iTunes/Apple" brand is permission to print money, so they can charge whatever they'd like for these downloads. People will buy them no matter what the price. AND, they can also apply the label selectively, steering consumers to whatever Apple stuck their name on this week. Labels will pay a LOT for this.
I gotta give it to Apple. They are really incredibly smart at manipulating consumers for maximum profit in a way that few other brands can do.
I don't respond to AC's.
Or, for one of the albums, you can get the MFSL version.
The gold plated CDs and ultra-heavy LPs may be a gimmick, but they do know how to mix masters.
I know many friends who have used higher compression on their FLAC files and, with my gear, I can clearly hear the artifacts. I realize most people won't but I've got mostly high end stuff, and I always burn in both my audio and network cables before using them and mark them with directional arrows (only with pvc-free tape and audio-grade markers) so that the don't get installed backwards after they've been burned in.
I'm amazed at how many people can't seem to grasp the fine points of lossless compression for audio work. I find most non-audiophiles expect that lossless means that what you put in exactly matches what you put out. I can tell you first hand, though, that when you spend as much money on gear as I have, you recognize that perfection comes from not just the bits, but the purity in which the bits are delivered. They may be the same ones and zeros, but a discerning ear can always tell the difference in the various lossless formats when listening to the color and soundstage of the reproduced performance.
Is it just my observation, or are there way too many stupid people in the world?
I want Vinyl quality.
This completely misrepresents what the 'Mastered for iTunes' represents.
If give the producer the tools and options to create CD quality files.
If a producer is putting a mastered for iTunes stamp ion the song that hasn't been improved beyond the most filmiest technicality, then it's on the producer.
There are a lot of issues regarding Apple products, and how Apple runs it's business. Lets not try to make some up, m'kay?
The Kruger Dunning explains most post on
"Apple recommends to mastering engineers not to compress a track. Owsinski says there’s a feature called Sound Check in iTunes that lets users hear all of their music files at the same level. He says a highly compressed track will actually sound less impactful because of the Sound Check technology. Moving beyond some of the technical aspects of mastering he adds that compressing is becoming less relevant because file storage is becoming less of an issue for consumers. This is why he theorizes that Apple is pushing its AAC Plus lossless high-resolution format (The existence of AAC Plus Lossless could not be verified)." .wav file and turning it into an mp4/AAC/Ogg/pick your poison.
The second falls within Applke's domain as it addresses the type of file and it's size as delivered to consumers.
The first has nothing to do with Apple. I'd love to see an Apple employee try and tell Bob Ludwig how he should be using his racks of high-end tube compressors and limiters. That would be a short conversation.
Audio compression during the mixing and mastering process has nothing to do with compressing a digital file to make it smaller. The first is a way of limiting dynamic range which is useful for several reasons such as creating a perceived loudness, making audio levels more consistent, or changing the character or transients through attack and release time settings. The other is taking a
Anyone know of peer-reviewed studies looking at these claims about audio quality? (forgetting about the compression artifacts for
now just considered raw wave forms) For instance, human
hearing tops out at about 22khz which is why the standard has been 44.1khz & 48khz sampling to get up to 22.05khz or 24khz
playback. Young people have hearing in this range but it falls off with age so I'm not entirely clear why 96khz is needed.
According to the nyquist limit you need to 2x samples of the waveform to reproduce the original. Maybe I'm misunderstanding
something? For instance if you have a pure tone of 100hz sampled at 200hz or 1000hz is there an obvious difference is sound quality
when played back? Similarly 16-bit allows ~65k possible amplitude levels whereas 24bit gives ~16.7million. But in terms of perception
I haven't the foggiest idea how much the human auditory system can actually distinguish. Anyone well versed in auditory perception want to
chime in? As a techie I'm all for bigger numbers to put on products, but is this the case of the psychology of audiophiles thinking they can tell
a difference when in actuality its pretty unlikely except for perfect audio conditions (i.e. in a sound isolated lab) and a prime auditory (young ears)
Compared to what? People who buy what could be described as music files on a plastic disc?
Isn't that the point? This is confusing: " no difference from the CD " ... "someone needs to offer CD quality downloads..." .
The point for "Mastered for iTunes" is not to make it different from the CD, it's to make the compressed, lossy AAC file as close to the CD as possible. It sounds like they've done that.
That being said, you would probably have a better indicator of errors if you did use a source that was not heavily gain compressed before data compression, but that is another debate.
No, that was actually my point. If you use the CD as a master, and the CD is heavily compressed (as is the case here), there will be far less difference between different compressed versions. You're not going to get anything that sounds better than the master you use, cause the bits that are gone are gone. And in the case of RHCP CDs, that's unfortunately most of the bits.
tl;dr: GIGO
Apple has a lossless format, but they don't use it.
Who actually buys music from iTunes?
whatever the world champion of compression is nowadays
My vote is for Nickelback's latest. I have never seen a waveform so deprived of any information - it's on or off, with absolutely no headroom.
Apple doesn't claim Mastered for iTunes tracks sound more like CD. Apple claims they sound more like what "the artist and sound engineer intended." Apple requests far higher quality material be submitted to iTunes than CD quality. That means Mastered for iTunes tracks will sound different from CD and [i]better[/i] than normally ripped tracks. The raspy sound during the null test is attributable to errors in the CD.
It depends on the equipment and room. As important though, is the program material. Take pretty much any chart release right now and it's irrelevant as those tracks are pretty much squashed to death to begin with. Something like Joni Mitchell's Blue, or Miles Davis, or well engineered orchestral music ... yes, there is a difference and it's noticeable. Then again, it's my job to notice (audio engineer)
What good is an optimized (if not lossess) format when played through and iPod with a digital to analog converter that costs 50 cents? My $40 Sansa Clip plays FLAC and has a better quality DAC than a $300 iPod. Why is Apple even bothering?
Here's what the article actually says: If you have a sound engineer who creates a recording with material that is badly distorted in the first place, then whatever Apple tries to do with "Mastered for iTunes" is not going to help, and the AAC encoded material sounds the same as AAC encoded material converted from a CD.
According to the article, the recording itself is not clipped, but it sounds as if clipping has happened at some time earlier in the production. Garbage-in, garbage-out principle.
First problem:
Subtracting one waveform from another to look at the difference, doesn't prove there are audible difference in the case of AAC vs CD.
It just proves that one file is using perceptual encoding, which we already know.
Perceptual encoding changes the waveform, but that does not prove that the difference is audible when in the original file being masked by louder material. To prove that you would need Double blind listening tests.
So that point is a total failure.
Second problem.
"Mastered for iTunes" produces 24 bit files, this offers more dynamic range than CD. But in order to see a benefit, your source material also needs more than 16 bits of dynamic range. You are lucky if RHCP has 10 bits of dynamic range.
So again, nothing proved.
Content is absolutely critical. I find live content particularly with crowd noise and applause can really give the encoders trouble.
Do you not get CD-quality sound when you download a song in Apple Lossless format?
I have a CD (I think it was either "Machinehead" or "Bad Company" that has a very noticeable hiss on some systems.
It reminds me of when I played tapes in crappy decks, and makes me wonder if the CD was recorded from a cheaper analog system. On tapes it probably would have been *less* noticeable as many decks actually had noise-reduction stuff build in.
This is a store-bought CD, not a burn.
"Shepherd compared three digital music files...with a CD version of the same song, and said there were no differences. Apple or someone else needs to step it up here and offer some true 'CD quality downloads.'"
Does anyone else notice the contradiction in that statement?
Even on the best audio equipment ever made, the Red Hot Chili Peppers would hurt my ears.
http://www.scientificamerican.com/article.cfm?id=is-space-digital
From the article: Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences. Apple or someone else needs to step it up here and offer some true 'CD quality downloads.' So let me get this straight, this guy compared the Mastered for iTunes format with the CD version and found no differences. Then the headline says someone needs to "step it up here and offer some true 'CD quality downloads". So given the first statement, it seems to be that Apple is in fact offering 'CD quality downloads'. Am I missing something here?
Apple's "Mastered for iTunes" is a set of guidelines about how to turn a master recording into an iTunes-optimized digital file. The author of TFA, however, is talking about taking a CD track and making a compressed version that's as close as possible to the CD track. A CD track is NOT a master file. (We don't want a track that's merely a CD representation - we've heard plenty on
So of course if you make an iTunes track from a CD track via the "Mastered for iTunes" process, you'll get a 256 kbps VBR AAC that's identical to ripping a CD track to a 256 kbps VBR AAC. However, if you follow Apple's recommendations, quoted here:
To take best advantage of our latest encoders send us the highest resolution master file possible, appropriate to the medium and the project.
An ideal master will have 24-bit 96kHz resolution. These files contain more detail from which our encoders can create more accurate encodes. However, any resolution above 16-bit 44.1kHz, including sample rates of 48kHz, 88.2kHz, 96kHz, and 192kHz, will benefit from our encoding process.
you'll probably get something different, perhaps better, than a CD track ripped to AAC.
Apple is providing the tools they use to convert to AAC so that sound engineers can preview the product before it goes on sale, but they appear to be the same tools they've been using all along. As I said before, "Mastered for iTunes" isn't a new encoding tool - it's a process workflow. Other recommendations:
- Apple recommends listening to your masters on the devices your audience will be using
- Be Aware of Dynamic Range and Clipping
- Master for Sound Check and Other Volume Controlling Technology
- Remaster for iTunes [That is, they suggest starting over from the original recordings, rather than send in a file that was mastered with CDs in mind.]
"Mastered for iTunes" is indeed optimized for iTunes: it's optimized for separating the gullible from their money.
Oh, the beautiful gloss of greality!
Using RHCP records as a basis for comparison is a terrible example; everything they've brought out since One Hot Minute has been overcompressed to death at multiple stages in production (Californication is even cited as a specific example of a crappily mastered record in the Wiki article).
Shortly after reading this article on ars I went to check it out for myself. Yes, technically they are still "just" 256k VBR AAC files just like other stuff in the iTunes Store. But if the engineer doing the mastering has busted his/her ass to play the cat & mouse cycle of re-tweaking the dynamics after listening to the encoded result a few times, the results are extremely surprising.
If you've got a good stereo or a nice pair of headphones, go listen to a normal CD version of Jimmy Smith's "The Cat" ripped at 256k VBR AAC, and then listen to the "mastered for iTunes" version. I had no idea lossily compressed audio from 40+ year old analog master tapes could sound that good.
The low-to-0 moderator scores on the most relevant, factual comments indicate to me that the blogger, submitter and moderator are clueless about Mastered for iTunes.
Different enough that MD5Sum doesn't show them as duplicates :-) Presumably different enough that a phase-inverted null test has a result that is within the threshold of human perception -- at which point we are into subjective territory and would require a significant sample of listeners in a blind test in order to make a subjective determination. I'm also willing to bet (any bet you can cover) that a properly conducted controlled A/B/X test will not give a meaningful result when comparing a high-quality MP3 with a Redbook CD of any typical pop music genre. There are edge cases (like solo Oboe) that are poorly encoded by the commonly used MP3 algorithms, where a contrived test will be easily skewed. Lower bitrates tend to be more perceptible in actual practice than is often assumed. Listen to cymbals and triangle hits, and you'll hear compression artifacts from time to time, you don't need golden ears for that. There are also artifacts associated with imaging in the stereo field, and also it's pretty common for compression algorithms to affect stereo panning in ways that are audible, particularly to someone who is extremely familiar with the material who is listening analytically in a controlled environment -- such as when producing one's own track.
TL;DR, if the differences are not within the threshold of human perception, then they don't matter musically. However, don't assume that MP3 encoding is outside that threshold, because sometimes this is not the case, even if it is mostly true.
Correct, FLAC is not inherently "CD quality" — it's more flexible.
CD quality is (two channel) 16 bit samples at a 44.1 kHz rate. FLAC can handle CD quality because it handles a range from 4 to 32 bit samples and frequencies from 1 Hz up to about 650 kHz stored in up to 8 channels. So FLAC has your quality range covered. You could not want for a more capable format. (I think the frequency range means you could encode a substantial chunk of commercial AM radio signal?)
As others note, this the capability range of FLAC, not necessarily the quality of the source signal you're encoding.
FTFAS:
If there are no differences between a Mastered for iTunes format song and a CD version of the same song, what's the bitch? Does he want better quality from a downloadable version?
the Nyquist limit that says you can encode at twice the sample rate applies when encoding a single sine wave.
Or a sum of sine waves, so long as the sample rate is greater than twice the highest frequency. (You need the twice to capture the phase as well as the amplitude.)
I have not heard any music recently that is made entirely of pure sine waves.
People building on the work of Fourier have showed that all music is made of pure sine waves, at least over the short term. Audio codecs divide the signal into "frames", each roughly as long as a video frame, which overlap slightly. Over such a short time period, the fundamental frequency and overtones of each instrument look like pure sine waves. The "underwater" effects in early MP3 codecs came from faulty assumptions about how to deal with transitions from one frame to the next.
An often made error in sample rates involve confusion between sample rate and bitrate. Bitrate is bits per second such as the rate your dial up modem can send including start/stop/parity bits with data bits. This should not be confused with sample rates. Sample rate is how often a sample is captured. For the often touted CD Quality claim of 44.1 Khz, remember that a sample is 16 bits per channel. This is a 32 bit sample taken 44.1K times per second. This does not include any framing, error correction (ECC), encoding (EFM Modulation) etc needed to support Uncompressed audio.
Without any overhead the raw data bit rate for a CD is 44.1K samples per second Times the sample size of 32 bits. This is 1411200 bits per second.
The truth shall set you free!
It is pretty pathetic that iTunes can't even get CD quality. CDs which have been available since the 80's. Why the fuck aren't people selling music with higher quality? There used to be DVD-Audio which was way, way better than CD quality but ever since iTunes all music quality has gone to shit. Give me better fucking quality wtf it is 2012 and we are still using fucking blades on our skin to shave. We should have been using lasers in the 70's and perfected neural implants in the 90's and just will your hair to be shaved or grow with the power of your mind.
The Official Site of 1337 Pwnage
In this video interview with Neil Young, he states that dominant digital audio formats are inadequate and 'some rich guy' needs to build a new iPod that will play up to 30 albums. I don't think he's heard of flac or the Sansa Clip+ (or MOST Android devices).
Most modern music is brick-walled these days anyway. Loudness is winning over dynamic. Half of the reason I find vinyl more pleasing is because it's usually mastered with a lot taken off the limiter.
Any thoughts on Korg's AudioGate? Is DSD even related to this conversation?
Actually, chances are the cheaper the gear the better they will sound, as that's what they are mastered for.
First let me start by saying, lossy compression has absolutely no place in mastering. Capture you samples at the highest resolution possible 24-bit/96Hz is passable, 192Hz is better. If you're mastering music on a machine that can't handle this, then simply take when you're given and be off with you.
The author of this article makes claims about performing an analysis of the Apple Mastered for iTunes method. I didn't like his form of analysis. There are major issues with comparing lossy to lossless audio since we have to decide if we want to perform individual listening tests, which often yield nothing of any interest since most "Super Listeners" generally are pretenders to begin with. Frankly, at 24-bit/96Hz or better using high bit rates (as would be used for mastering) chances are, you don't have suitable speakers or headphones to perform the test reliably anyway. Even the best monitor speakers from Genelec can't reproduce the differences at these levels. Some headphones might be able to handle it in some ranges, but not in all. Therefore we're limited to what is possible with pure data analysis.
In data analysis, we can do things like invert the wave of the output and add the results together to produce a distortion wave. As the author claims to have done, but now comes the issue of deriving anything meaningful from this. Often times, better codecs will produce greater distortion because it's supposed to be "meaningful distortion". As such, think of it like dithering an image to improve results from image compression, this is extremely common when down-sampling before compressing. As a result, filters will produce more accurate AC characteristics of the waves being compressed. This comes at a cost of bit rate consumption, but the end result when the image is decompressed is higher.
Some numbers like SNR (signal to noise ratio) are calculated by deriving a meaningful number to calculate how much of the original signal still exist in the compressed signal. Higher distortion such as what this guy is observing can in fact produce better signal retention.
Next is the issue of attempting to produce the best audio output possible based on what the listener perceives as being superior sound. This is a very common issue in audio compression. AAC originally defined 7 possible branches for compression methods which would be selected per audio unit based on a vendor specific 'Psycho-acoustic model". This would attempt to choose the best balance between bit rate allocation and what should sound best to the user. Often these models just tried all 7 compressions and built a quality metric related to how the audio should sound in the end and chose the best output and moved on. Now, though I could be wrong, I believe I know of 21 possible branches for the compression. While each one has its benefits, for a computer to choose one branch over another requires the computer to have a concept of what sounds best. Rarely is it chosen based on pure wave distortion. Often it's chosen based on concepts like "we can improve the quality of this signal by increasing the high frequency distortion since in those ranges, it wouldn't be reproducible by anything other than piezoelectric elements far too small to be heard."
So, in the end, while he may be actually on to something, his reasoning is likely entirely incompatible with reality. Lossless compression chooses how best to lose based on perceived quality as opposed to pure signal quality. A perfect compression would lose nothing and still chop audio to 1/50th the original size. But in this universe, the best lossless compressions still struggle to perform 2:1 reliably and while it can often average or peak at 4:1 can often also end up increasing the size instead. Most of the old Ella Fitzgerald/Loius Armstrong recording are examples of worst case files.
So, while his analysis was very cute, it was possibly inaccurate.
Now, I'll reiterate the first point.
Audio compression DOES NOT BELONG in a mastering environment. Lossless is ok if there's a
You see that Nyquist limit is the requirement to reproduce the FREQUENCY. But it doesn't reproduce the amplitude. You need 2-3x as many points, depending on how much energy there is in the frequency.
At the Nyquist limit, you get 22kHz (which is within most children's hearing and still quite a way in from GOOD adult hearing, getting up to 25kHz, still) but can't tell how much power (amplitude) it has.
To get the amplitude right, you have to look down to 7-12kHz as your maximum frequency.
Since MOST of the energy in a pop song is in the band below 12kHz, this doesn't become a problem for pop music. But orchestral and synthetic pieces, especially when there are only a few instruments, can easily sound bad at "CD quality". A piccolo would sound too similar to a tin whistle, for example. In the volume of an orchestral crescendo you won't hardly hear them, and miss the difference. But on its own, it won't sound right.
He says there's no difference between the Mastered for iTunes AAC and the non-Mastered-for-iTunes AAC. BOTH were different from the CD.
"Shepherd compared three digital music files, including a Red Hot Chili Peppers song downloaded in the Mastered for iTunes format with a CD version of the same song, and said there were no differences. Apple or someone else needs to step it up here and offer some true 'CD quality downloads.'""
Surely if there were no differences between the CD version and the AAC file, that means the AAC version _is_ CD quality? Quality loss would be a difference, right?
i feel compelled to respond: mp3 vbr
You would think a master engineer would look into the program a little before making a fool of himself. The program is a set of guidelines for mastering, not a different file formats. A lot of engineers may be using similar guidelines when creating their iTunes submissions anyway. There would be no difference in file format. None is claimed. Anywhere. By Anyone.
Though experiment. Take a 1 KHz tone sampled at 10 KHz, phase shift it 180 degrees as described in article, thats 5 samples phase/temporal shift. On the other hand in the 100 hz band you need to shift 50 samples for the same degree phase shift.
and this is part of why the guy is a total non-authority. He is a "mastering engineer" (where did he get his degree, exactly?) who doesn't know the difference between phase and polarity.
There used to be DVD-Audio which was way, way better than CD quality but ever since iTunes all music quality has gone to shit.
DVD Audio is still around.
DVD-Audio authoring software is available for various OS platforms:
For Linux (and BSD and Solaris),
http://dvd-audio.sourceforge.net/
For Mac OS
Burn - open source, free
still running on PPC Macs from OS X 10.3.9, also on Intel Macs, a 64bit-version available, too:
http://burn-osx.sourceforge.net/Pages/English/home.html
Minnetonka Disc Welder - commercial
http://www.minnetonkaaudio.com/index.php?option=com_content&view=article&id=70&Itemid=93&lang=en
For Windows
Minnetonka Disc Welder - commercial
http://www.minnetonkaaudio.com/index.php?option=com_content&view=article&id=70&Itemid=93&lang=en
DVD-Audio Solo - commercial
http://www.cirlinca.com/
You'll also need a DVD recorder capable of DVD-Audio and a respective player.
For PCs, LG Electronics and Pioneer used to have such hardware.