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Kirk McElhearn: Everything you need to know about digital audio files. (MacWorld)


Paul R
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While I do have a few small quibbles with some of the finer points Mr. McElhearn presents, this is a great 90 second read that provides a very good condensation of all the heehaw that we toss around. Without much technobabble, and with great focus and clarity. Worth the time to read, even if you already know all about digital audio files. :)

 

I added a small excerpt after the link. -Paul

 

Everything you need to know about digital audio files | Macworld

 

If you use iTunes or if you buy and download digital music, you’ll have come across a number of terms and abbreviations that describe digital audio files. This alphabet soup can be quite confusing. What are codecs or audio file formats? What is a bit rate, and what’s a sample rate? What does it mean when music is “high-resolution?”

This article covers what you need to know about digital audio files. I’ll tell you the difference between lossy and lossless files, I’ll explain why bit rates matter (or don’t), and I’ll help you understand the various file formats you may encounter.

Compression: lossy and lossless

 

When you buy a CD, the audio on the disc is uncompressed. You can rip (or import) CDs with iTunes or other software, turning the CD’s audio into digital audio files to use on a computer or a portable device. In iTunes, you can rip in two uncompressed formats: WAV and AIFF (other software allows for other formats). Both formats simply encapsulate the PCM (pulse-code modulation) data stored on CDs so it can be read as audio files on a computer, and their bit rate (you’ll learn what the bit rate is below) is 1,411 kbps.

WAV and AIFF files can be quite large. As such, digital audio files are compressed to save space. There are two types of compression: lossless and lossy. Lossless includes formats (or codecs, short for coder-decoder algorithms) such as Apple Lossless and FLAC (the Free Lossless Audio Codec). Lossy includes the ubiquitous MP3 and AAC formats. (AAC, which stands for Advanced Audio Coding, is, in reality, the MP4 format, the successor to the older MP3. While Apple adopted it early on in iTunes, Apple was not involved in its creation, and has no ownership of this format.)

You may see other audio formats too, though they are less common. These include Ogg Vorbis, Monkey’s Audio, Shorten, and others. Some of these codecs are lossy, and some are lossless. However, if you use iTunes and Apple hardware, you’ll only encounter WAV, AIFF, MP3, AAC, and Apple Lossless, at least for music.

 

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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Thanks for the kind words!

 

I'd love to hear your quibbles. I wrote this for a general audience, so I certainly simplified some things, but I'm always interested in constructive criticism.

 

Kirk

 

Perhaps you can peer into the future a bit - can you "rip" MQA encoded audio files technically (into other formats, etc.) with existing software, and can you do so legally?

Hey MQA, if it is not all $voodoo$, show us the math!

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Thanks for the kind words!

 

I'd love to hear your quibbles. I wrote this for a general audience, so I certainly simplified some things, but I'm always interested in constructive criticism.

 

Kirk

 

 

They are truly quibbles, not serious stuff at all. I think your article was well worth posting for other folks to enjoy, though I probably would have asked you first if I knew you were on here...

 

In any case, since you asked... the link to the 24/192k article was quibbly. I do not think I have ever heard a 24/192k recording that distorted. I do not think there is anything inherent in the sample rate to cause distortion.

 

And it was a most minor point - especially for non audiophiles.

 

It might have been interesting to include a paragraph that describes how almost all DACs, even those limited to 16/44.1 inputs, resample the input to very high sample rates before sending it through the actual D2A conversion. It is an endlessly fascinating subject around here. :)

 

I would also have liked to see more about DSD, and the new crop of portable DACs that hook up to iPhones and iPads and produce some really top quality sound. But that would have been of limited interest to your target audience, at best.

 

All quibbles - which are utterly trival points that detract nothing at all from the overall work. Well done work too, IMO.

 

Glad to see your here at CA.

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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Thanks, Paul. As you can expect, I had a word count limit. My goal was to cover things that "average" users would wonder about. Maybe in the future I can pitch another, more advanced article about those things.

 

As to the question about MQA, does anyone have a link to anything describing that format? I went to the website, and listened to the video, using weasel words like "folding" to talk about compression. It sounds a lot like homeopathy, the way it's described.

 

Kirk

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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Thanks for the kind words!

 

I'd love to hear your quibbles. I wrote this for a general audience, so I certainly simplified some things, but I'm always interested in constructive criticism.

 

Kirk

 

Very nice piece, Kirk.

 

Tiny edit suggestion from this former computer magazine editor:

 

After your first mention of the Apple Lossless format, add something in parentheses like "aka, ALAC" because while iTunes never uses that acronym, readers will still see it out in the world.

 

Dave, who held that edit job from the mid-1980s to the mid-1990s

++++++++++++++++++++++++++

Music is love, made audible.

++++++++++++++++++++++++++

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Very nice piece, Kirk.

 

Tiny edit suggestion from this former computer magazine editor:

 

After your first mention of the Apple Lossless format, add something in parentheses like "aka, ALAC" because while iTunes never uses that acronym, readers will still see it out in the world.

 

Dave,

 

Good point. Apple actually does use it on their support site, on some pages, such as this:

 

https://support.apple.com/en-gb/HT204925

 

But it's true that the general public will see that acronym.

 

Of course, with that logic, we might want to start saying things like "iPod touch (aka iTouch)" because of what consumers often write. :-)

 

Kirk

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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Dave,

 

Good point. Apple actually does use it on their support site, on some pages, such as this:

 

https://support.apple.com/en-gb/HT204925

 

But it's true that the general public will see that acronym.

 

Of course, with that logic, we might want to start saying things like "iPod touch (aka iTouch)" because of what consumers often write. :-)

 

Kirk

 

Ah, but your article is about computer audio files, not devices, so perhaps "that logic" does not extend.

 

And it's not just consumers who write "ALAC," but most manufacturers whose devices are compatible with that format.

 

Dave, who says being an editor is like the old commercial for the U.S. Army in that "It's not a job, it's a character flaw"

++++++++++++++++++++++++++

Music is love, made audible.

++++++++++++++++++++++++++

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Thanks, Paul. As you can expect, I had a word count limit. My goal was to cover things that "average" users would wonder about. Maybe in the future I can pitch another, more advanced article about those things.

 

Now that you have opened the floodgates, I expect questions will pour in. :)

 

Not sure a more advanced article is needed, more like on the same level covering the stuff people will encounter as soon as they "scratch the surface."

 

It did occur to me that a 24/192k file may sound distorted when played through iTunes, which will resample it down to whatever the audio-MIDI settings are. That is commonly set to 16/44.1. iTunes automagic resampling can be the source of really perplexing results. Understanding what it is doing and how to fix it would be a challenging article. :)

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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Not sure a more advanced article is needed, more like on the same level covering the stuff people will encounter as soon as they "scratch the surface."

 

If there were a more advanced article, would would you all think it should contain? Macworld is generally amenable to that type of stuff, since most of what I write about iTunes - and I write about it regularly - gets good traffic. (I know, it's a shame to think of traffic, but that's what pays the bills.)

 

Kirk

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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It did occur to me that a 24/192k file may sound distorted when played through iTunes, which will resample it down to whatever the audio-MIDI settings are. That is commonly set to 16/44.1. iTunes automagic resampling can be the source of really perplexing results. Understanding what it is doing and how to fix it would be a challenging article. :)

 

That's a good point. I covered that in an article back in 2011:

 

How to find and play high-resolution audio on the Mac | Macworld

 

But that could use a refresh. I'd need to get a DAC that handles above 96 kHz (which is what mine does). Or even one that can handle DSD...

 

However, I think your idea is more one of trying to figure out exactly what happens, what gets sampled and when. And that's something that's really hard to find info about. Apple doesn't give any information about it.

 

Kirk

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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If there were a more advanced article, would would you all think it should contain? Macworld is generally amenable to that type of stuff, since most of what I write about iTunes - and I write about it regularly - gets good traffic. (I know, it's a shame to think of traffic, but that's what pays the bills.)

 

Kirk

 

Traffic is good. Keeps the pub afloat and that means you get checks for your work. Nothing is more aggravating than having a pub go out of business while they owe you a boatload of checks. (grin)

 

As far as "advanced" stuff, wow - there is a lot of material to mine there.

 

How about integrating iTunes with streaming devices? For example, Sonos, Blue Sound, playback on your iPhone/iPad? integration with products like the $10 BitPerfect app, which enables automatic rate switching in iTunes, and can also make DSD files playable? What do you do if you want to stream hi-res files? Metadata in iTunes is a lot better than most people used to think, but embedding the metadata into the files means you can rebuild an iTunes library from the media files without a lot of grief. Sharing iTunes libraries on more than one device, and so on. Separating the physical layout on disk from the iTunes library, backing up media and the iTunes library, interactions with TimeMachine, etc.

 

I think the problem is not finding the relatively advanced material, but in narrowing the subjects down to bite-sized chunks of information, so as to be digestible to the non-audiophile crowd. Not much of the above stuff is really "advanced", but neither it is exactly fit fare for a total beginner. I run into a lot of this from people wanting to put together their first music server. :)

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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That's a good point. I covered that in an article back in 2011:

 

How to find and play high-resolution audio on the Mac | Macworld

 

But that could use a refresh. I'd need to get a DAC that handles above 96 kHz (which is what mine does). Or even one that can handle DSD...

 

However, I think your idea is more one of trying to figure out exactly what happens, what gets sampled and when. And that's something that's really hard to find info about. Apple doesn't give any information about it.

 

Kirk

 

Look at the iFi Nano iDSD - hard to find fault with that little guy. Handles *everything* including DSD, and sounds great. Makes a very good headphone amp as well as a standalone DAC that isn't embarrassed when put up against far more expensive units.

 

nano – iDSD

 

List is $189 or thereabouts.

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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I think the problem is not finding the relatively advanced material, but in narrowing the subjects down to bite-sized chunks of information, so as to be digestible to the non-audiophile crowd. Not much of the above stuff is really "advanced", but neither it is exactly fit fare for a total beginner. I run into a lot of this from people wanting to put together their first music server. :)

 

Exactly. We generally run articles from 800-1000 words, and occasionally, as in this latest, I can ask for as much as 1500 words. So most articles have to have tight focus.

 

I've already covered a lot of what you mention, at least regarding iTunes. I did an article several years ago about playing high-res files on iOS devices, using third-party apps, and that could do with a refresh. I'm not sure that streaming high-res from an iPhone is that common, but I have covered other types of streaming a lot. (FWIW, I've probably written about 200 or more articles about iTunes for Macworld over the past ten years.)

 

One thing I hope to do is review the Fiio X7, which plays many formats, and could be an iPod replacement for some people. I'm waiting to hear back from an editor about whether they want to cover that.

 

As for actual add-on hardware (in response to your second comment), they're less interested in that. Remember, this is a Mac/iOS publication, so I need to stay within certain limits. I did write about DACs some years ago, when they started becoming affordable, but that's not something they're interested in.

 

Thanks for the ideas; I'm always interested in others. :-)

 

Kirk

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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...I did an article several years ago about playing high-res files on iOS devices, using third-party apps, and that could do with a refresh...

 

Over the next 3 to 6 months (or longer :) ) the "facts on the ground" could change radically around high res iOS devices (or any other kind of device/software), because MQA is going to enter the market. This will in particular impact streaming (e.g. Tidal will be switching their 16/44 "hi-fi" service to MQA).

 

Of course, Meridian hopes to conquer the world with MQA, and I believe the industry would not mind it as it is a proprietary/closed (with patented IP) format that has the potential to get DRM into audio (they call it "authentication"). I don't think Meridian is capable of pulling this off, but when Apple (or Sony, etc.) buys it watch out!

 

Might want to hold back a bit on refreshing that article...

Hey MQA, if it is not all $voodoo$, show us the math!

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As I said above, I can't find any technical info about MQA, other than someone saying that the music is "folded." Apparently, it's a proprietary compression format (lossless, presumably), with DRM, so it'll probably be dead in the water.

I write about Macs, music, and more at Kirkville.

Author of Take Control of macOS Media Apps

Co-host of The Next Track podcast.

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As I said above, I can't find any technical info about MQA, other than someone saying that the music is "folded." Apparently, it's a proprietary compression format (lossless, presumably), with DRM, so it'll probably be dead in the water.

 

Maybe not so much audio homeopathy as audio origami.

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Very nice piece, Kirk.

 

Tiny edit suggestion from this former computer magazine editor:

 

After your first mention of the Apple Lossless format, add something in parentheses like "aka, ALAC" because while iTunes never uses that acronym, readers will still see it out in the world.

 

Dave, who held that edit job from the mid-1980s to the mid-1990s

 

FWIW, ALAC and FLAC are practically identical algorithmically speaking.

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As I said above, I can't find any technical info about MQA, other than someone saying that the music is "folded." Apparently, it's a proprietary compression format (lossless, presumably), with DRM, so it'll probably be dead in the water.

 

It's lossless only in the sense that mp3 is, i.e. not. Less lossy, yes, but the marketing is still misleading. The best info you're likely to find at the moment is probably Meridian's patents.

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As I said above, I can't find any technical info about MQA, other than someone saying that the music is "folded." Apparently, it's a proprietary compression format (lossless, presumably), with DRM, so it'll probably be dead in the water.

 

I think this guy does the best overall and balanced (rather than just repeating Meridian marketing gobblygook) presentation:

 

 

edit: The DRM word is wisely avoided, with "authentication" being used. As of now, it is open in that "legacy systems" (i.e. non MQA hardware DACs) are able to play it (though with a trivial sofware tweak in version 2.0, this can be rectified ;) ). Analysis by some around here is pointing to the fact that an MQA file played on non-MQA DACs is in fact slightly degraded (contradicting Meridians promise) but how audible it is in question.

 

One has to string together "ifs" right now, like IF MQA on Tidal is impactful (or even if Tidal survives) and IF Apple or Sony buys MQA IP, etc., but I am not willing to call it dead yet. Of course, around here in the "audiophile" space its promise of "high res" streaming is a big deal...

Hey MQA, if it is not all $voodoo$, show us the math!

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