File This

A Brief Discussion of Audio File Types

This article first appeared Recording Magazine. I reprint it here with permission, and I encourage you to subscribe to that publication, as they are a stand up bunch of folk!

In my article “Keeping Track”, we covered data. We talked about the information you need to keep with your songs in order to sell, license and organize them. We covered metatags; data about data that gets embedded in files. We talked a little about the file types that carry metadata and how to use them, and that brought up a wider topic: audio file types.

There are hundreds of audio formats and an endless variety of settings and options. So, without a whole lot of fanfare, we’ll dive into some of the formats that exist as of now, but first let’s delineate a few traits and categories.

Compression

An audio file (or a video file for that matter) is either compressed or uncompressed. What this means is the file is either whole and complete or it has been squashed down to save space, like using a .zip file; or in physical terms, like using one of those infomercial vacuum bags to suck the air out of your Christmas sweaters. A WAV file is uncompressed; an MP3 is compressed.

Don’t confuse compression or the lack thereof with the terms lossy or lossless. Lossy and lossless are two types of compressed files. If a file is lossy, it means some data has been thrown out because in theory that data isn’t necessary, usually because the human ear can’t hear it. That data cannot be recovered. On the other hand, a lossless file is compressed, but no data has been thrown out. Think of the difference between cutting off the sleeves of your sweater (because it’d be fine as a vest) and sucking it in Mr. Popeil’s vacuum (lossy), and simply sucking it in the vacuum, but leaving it intact (lossless). As you might guess, lossless files are generally bigger. MP3s are lossy. FLAC files are lossless.

File Format and Codec

You may never need to know this, but there is a difference between a file’s format and it’s codec. The format, or file type, is simply the wrapper in which the audio data is kept. The codec is the meat of how it’s encoded. Not all file types support all codecs, but there are some surprising possibilities. A WAV file might not be encoded with PCM, for example. We don’t have room here for a comprehensive list, but it’s likely you’ll only ever need to worry about a few possibilities. We’ll say more on those big ones momentarily.

Sample Rate, Bit Depth and Bit Rate

These are the main measurement of audio quality, and there can be some confusion about what they all mean.

Sample rate is used to refer to an original or uncompressed recording. It’s how many times per second a snapshot of the signal is taken. 44.1k means 44.1 kilohertz, or 44,100 times in a second. You probably know that CD quality is 44.1k, 16 bit.

Bit Depth is how many bits are in each sample. If you record at 44.1k, 16 bit, you’re taking 44,100 16 bit samples every second. Crudely, more bit depth corresponds to more dynamic range.

Bit Rate can be a bit fuzzier. Bit rate simply means the number of bits that are processed over a given amount of time, and it is a measure that can be applied to any file. A CD quality file is 1,411 kbps (kilobits per second), for example. In practice, though, bitrate is more often used to refer to the quality of a compressed, lossy file. To be crude again, it comes down to a measure of how much data we’ve thrown away. The highest bit rate for mp3s is 320 kbps, and the default iTunes rate is 256. A 128k MP3 is noticeably smaller than a 320k file, but in many situations, not all that different sounding. A 32k MP3, however, would sound awful, except in special circumstances (audiobooks, for example, often use low bit rates, because that doesn’t much affect a spoken track).

The Big Ones

While there are actually tons of audio file types and different combinations of format/codec possibilities, there are only a few you’re likely to see very often. In fact, we can narrow that down to three. WAV, AIFF, and MP3.

WAV (Waveform Audio File Format) files are Microsoft’s format, used in PC applications, and based on RIFF (resource interchange file format). Usually WAV files are encoded using PCM (pulse code modulation) encoding, which is uncompressed and the same basic encoding used in CDs, but it is possible to encode a WAV file with other codecs, even compressed ones. A “RIFF Wav” is a normal WAV file, and a “Broadcast WAV” is a WAV file with extended headers, originally used by broadcasters. WAV files have .wav extensions.

AIFF (Audio Interchange File Format) files are Apple’s uncompressed format, also based on RIFF, and usually using PCM encoding. The only practical difference between WAV and AIFF files is that AIFF files allow more metadata by default (so you can see stuff like album covers in iTunes), but you will notice that certain DAWs won’t deal with both. That’s not a problem, as you can easily convert between them with something like Sox or FFMPEG, or free software like Audacity. AIFF files typically carry .aif extensions.

EDIT with a sneak pro tip: AIFFs and WAVs are literally the same format, from an audio standpoint. So if Joe Schmo who uses GarageBand sends you a bunch of AIFFs that your Windows DAW can’t read – you can just change the extension and voila.

MP3 (MPEG Audio Layer III) files are compressed, lossy and very common. MP3 shouldn’t be confused with MPEG-3, which is a video format. MP3 compression is done by throwing away data which isn’t needed, mostly due to a phenomenon in human hearing called auditory masking. That’s a pretty fancy way of saying we don’t hear everything in an uncompressed file anyway, so we might as well throw some away to save space. There’s no shortage of debate there, but it seems to work pretty well. MP3 was a proprietary format, owned and licensed by the The Fraunhofer Institute of Integrated Circuits, and that’s why not all software could make an MP3, at least until very recently. The Fraunhofer Institute declared MP3 an obsolete format in May of 2017, and terminated its licensing program. Whether this means the MP3 will die or proliferate further remains to be seen. For now, it’s still the de-facto compressed file format, and typically what you get when you rip a CD with iTunes or other software, or download that free track from your favorite polka band.

Other Major Formats

There are so many audio formats, we’d be hard pressed to talk about them all here, but there are a few you should know about.

CDDA (Compact Disc Digital Audio) is the format for compact discs. It’s just an AIFF file with different headers. If you happen across a .cdda file (probably ripped from a CD), you’ll probably be able to play it in anything that can play a WAV or AIFF.

AAC (Advanced Audio Coding) is a compressed, lossy format created by Dolby which was designed to be a successor to MP3. Apple subsequently developed a copy protected version that uses DRM (digital rights management) for iTunes, and that’s generally the format of files you buy from iTunes.

FLAC (Free Lossless Audio Codec) is exactly what it sounds like, a free, lossless, compressed format. Great for archiving files, since it can reduce size up to 60% without losing any quality.

WMA (Windows Media Audio) was originally a compressed, lossy Windows format designed to compete with MP3. It’s been expanded to include a lossless version, a multichannel version, and a lower bit rate version used for voice. You may encounter Windows system files or other similar things in WMA format. WMA files can be copy protected.

AC-3 is a lossy 5.1 surround sound format used by Dolby Digital in DVDs, HDTV and DTV (digital television). Its highest sample rate is 48k. A side note: The “point one” in surround sound refers to a Low Frequency Effect (LFE) channel which has less bandwidth. The LFE is where the shake your boots BOOM in movies comes from.

What To Use?

At this point your question may be why should I care, or what should I use? The truth is, audio is audio, and when it comes to format choice, utility is the main consideration. Your DAW will do what it does, and I recommended letting it do that. When you’re deciding what to export, think about the use at hand. You’ll want to export either WAV or AIFF for mastering, making CDs, importing into a video project, or other continuing full resolution work. They’re really the same thing, so think about the software you’re using next, or what the person on the other end needs, and use that.

When it comes to delivery to the general public, think about the end user rather than entering into an endless debate about the perceptual quality of various algorhythms or codecs. If you’re selling downloads to normal people, you’ll probably want to use MP3s. If you’re delivering files to a digital distributor, you’ll probably be asked for CD quality WAVs, and in some cases, distributors will take AAC files for iTunes. If you want you can also distribute lossless files in FLAC format, or give people access to WAVs, or even distribute OGG/Vorbis files, which is an open source container/codec combination very similar to MP3. Beware, though, that not all players support these less common formats, and your user may end up with no way to listen.

As far as bit rate, I like to give my loving, devoted fans the highest quality MP3s I can, so those are encoded at 320k, but it’s also a good idea to make a 128k version for web-based preview listeners, because the smaller size will load faster and stream better. Some submissions you make (say to internet radio or licensing folk) may have size limits, too, so those smaller MP3s are useful. In the end, this is a judgement call, and if it’s for your own personal listening, then do whatever you like best.

One other consideration is something we addressed in “Keeping Track”, which is metadata. There are many situations where you’ll want some data other than audio in your file. Whether it’s so consumers know who you are, or licensing agents know who to contact, you’ll need some extra info in there, so the file type you use to send to certain people needs to contain that data. That’s what we covered in “Keeping Track”, so if you haven’t seen it, check that article out.

Resources

As with any very technical topic, an exploration of audio file types can go quite deep, and we don’t have room here to cover everything we could think of, so here are some recommendations for further reading:

Principles of Digital Audio by Ken Pohlmann
The Audio Expert (chapter 8 especially) by Ethan Winer
Mastering Audio by Bob Katz
How Music Got Free by Stephen Witt (for a great history of the MP3 format)
Any Wikipedia page about “audio file types” or specific types – google “WAV Wikipedia”, for example.

If you’re new to audio or recording, then hopefully we’ve helped you at least begin to sort out file types in digital audio, and if you’re a veteran, I hope you’ve reminded yourself of a few things here. For the most part, file types are pretty straight forward, but you can run into confusion at times, especially when a DAW or other piece of software gives you a thousand choices. It’s nice to remember a few basic tenets, cut through the noise, and get back to creating. So file this away, and we’ll see you in the studio!

Did you know I have a master’s degree in “Music, Science and Technology” from Stanford University? That means I can go back and forth between Macs and PCs in the studio, and talk at length about debt. Find me on Facebook and Twitter and other various stuff @AaronJTrumm.

Change?

October 15, 2013 by Aaron

Music Thoughts, Rants, Randomness

aaron j. trumm, albuquerque, bring it back, change, free music, m.c. murph, manny rettinger, music, nquit music, rap, slam poetry, ubik sound

I have an old old song called “bring it back“. What it’s about is how I would sometimes go back into my older material, listen to it, and find out that it was better than I thought, and get all inspired. As if I was listening to someone else’s music.

I’ve found over the years that this process is kind of crucial for me. every so often (a year? two? fifteen?) I end up going and listening through a bunch of stuff that I’d practically thrown away I thought it was so bad. But I always find ideas and notions – as if I were my own muse.

I do this with other people’s stuff too, of course. That’s most of what I do with listening is just pour over people’s stuff and wish I could make something like that and file these ideas away in my head.

What i was noticing tonight, listening to some of my older more angry stuff, is how wrong I’ve been in thinking that I just want to throw away my whole self – I don’t want to be as angry and upset as I was 10, 15, 20 – 2? 🙂 – years ago, but there’s a fierceness and a fearlessness in some of what I was doing that I don’t want to lose…

I have to figure out how to balance these notions. To be fierce, strong, wild, tough…these are useful tools – even anger is a gift, as ‘ol Zach Del Rocha once said (over and over 😉 ). But a violent fearful attitude, even when spoken fearlessly? I don’t know that I want that – no – I know that I don’t.

Maybe that song “bring it back” was a little more deep than I thought. It’s not just about looking back at your art – it’s about looking back at yourself – at life – at history maybe? And bringing forth the good from it into the future – and, hopefully…leaving the rest behind.

Ok – well – now that I’ve said that – why don’t you get some FREE MUSIC over at aarontrumm.com? 🙂

Whinerz

August 4, 2008 by Aaron

Artistic Apocalypse

m.c. murph, nquit music, whinerz

Well, if you shop for M.C. Murph at Barnes And Noble or any other of many mainstream retail outlets, including iTunes, you would know this song as “Whirlwheez”, since, as I shared in another post, the goddamned distributer used to ask you to mail in a HAND WRITTEN form with the CDs. God almighty. I don’t have good handwriting, and voila.

Anyway – I have samples in this one. From Xena Warrior Princess, when Xena was crazy. Also samples from Grosse Point Blank.

Some pretty egotistical stuff in the Xena samples. Ares is the man talking. God of War. Generally a bad guy in the show. Manipulating Xena with ambitious thoughts. Seemed to also make sense to me, though. I dunno. It’s a double edged sword, talking about beating and wrestling and molding life to your will.

The problem, see, is he’s trying to convince her to kill her own mother. For some other reason of his own which i forget. I think because it’ll drive her over the edge and make her his minion. Or something.

I’m not saying much here about the SONG. Well, you can just give it a listen, then.

**EDIT**
This album is actually discontinued, but you can probably still find it on Amazon or Borders or something – I think this will take you to being able to buy it on iTunes:
iTunes Artistic Apocalypse

Steam

August 2, 2008 by Aaron

Artistic Apocalypse

m.c. murph, nquit music, steam

I do a lot of bluesy sort of singing – sort of – I don’t know how to describe it really – I think of it as the “Voodoo Daddy” style because I used it on my slam poem/rap/song Voodoo Daddy, which I used at slams a lot with some success. Well this song “Steam” is the first I tried that, I think.

This song is weird. It’s called Steam and the chorus is talking about steam drowning me and etc. What that means is, during this time or a little bit before it, I had had this bad deal go down with my then girlfriend, where I found out that a YEAR EARLIER she had sort of run around on me one night, making out with this other dude. The thing is now if that happened, I wouldn’t care much. But then I was totally immature and fucked up about it. Anyway eventually she told me all about it and then I kept having this picture of the steamed up windows in the car (they were in a car). So I had this chorus about the steam.

It’s one of those songs, which I’ve mentioned before, where I have this chorus that is NOTHING to do with the verses! 🙂 The verses in this song are about Joan of Arc! 🙂 I was doing my history degree and we were studying Joan of Arc in some class, I think.

My favorite is when I distort the drum/bass and say Jesus Christ in French, and I whisper! “Jesuchriste” HEE HEE! 🙂

Austin Nights

August 2, 2008 by Aaron

Artistic Apocalypse

austin nights, m.c. murph, nquit music

My friend Spec who we just married off helped me perform this song one time. We dressed her and this hot blonde Molly (spelling might be wrong) up all sexy and they paraded around and acted too good for everybody while I rapped this song. It was great 🙂

The irony is, now I’ve just started rehearsing a new band. Right now it’s a three piece: me on keys and vocals, a drummer, and a guitarist. The guitarist was in a relationship with said Spec for 5 years after having met that night when she was being my too cool for school girl. Of course they broke up, she married someone else, and that sucks for my guitaring friend.

I think I might have talked about this song before. The first verse is about Babyface writing songs for TLC and the second verse is about the hit factory.

It’s sort of fucked up because right this second I’m not feeling that whole angry DIY feeling. Right this second I’m overwhelmed with too many different fucking things to do, which creates lack of focus, which makes one suck at everything a little, and I kind of almost WISH I was sitting in a room with a pad and a pen writing songs and doing nothing else. Let Quincy Jones run around putting it on the air.

Of course, I don’t think I want to say seven hail mary’s every billboard notch my song drops! 🙂

Interlude 3

July 30, 2008 by Aaron

Artistic Apocalypse

interlude 3, m.c. murph, nquit music

I like this one because I think that’s a neat thought that’s in here. You meet somebody famous and you freak out because what are the chances??? But really, the chances of meeting anyone are the same! So it maybe oughtta be a cherished amazing celebratory thing to meet anybody! 🙂

Also, Larrisse did these vocals. I wrote the thing but she said it. She didn’t want to, but I pressured her, and she knocked it out in one take. Only thing that bugs me is the wrong emphasis on the word “think” right at the beginning. But there was no way I was getting two takes out of her. Anyway she did it real good just boom bam wack.

also, boo!

Artistic Apocalypse Zen Row Your Boat Mix!

July 21, 2008 by Aaron

Artistic Apocalypse

artistic apocalypse, m.c. murph, nquit music, zen row your boat

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Awesome! I have a remix! It’s the title track! It has a remix! With different drums! And instruments! Etc! Neat! 🙂

I think that may really be all I have to say about this one 🙂

oh! except, why I called it zen row your boat mix i remember now – cuz i made the chorus a round – like row your boat! and it’s mellow – like zen! or something!

Quietly Manic

July 17, 2008 by Aaron

Artistic Apocalypse

m.c. murph, nquit music, quietly manic

I might have already blogged about this one somewhere. Yeah I’m pretty sure. Hmm. Well I like this one actually, it still sort of makes me speed up my typing as I blog, like it’s a soundtrack song to the revolutionary mission, and the revolutionary mission is working, and we’re winning, and etc.

I like it. I actually kind of want to put some version of this song into my new live sets. I wonder if I have the “vocalless” version somewhere. God. It’s probably on a DAT tape. Of course I have no DAT machine.

Well anyway – boom ba doom doom boom da doom boom ba doom doom boom da doom…mmmm 🙂

The Pair

July 16, 2008 by Aaron

Artistic Apocalypse

m.c. murph, nquit music, the pair

Tee hee. This one has Natural Born Killers samples. “you STUPID bitch, you STUPID bitch, you STUPID bitch”. This song’s supposed to be about me and Larrisse (my then girlfriend), how we’re so badass or something. But there’s no pair, dude, because it’s not a duet. But I TRIED to have it be a duet. Wanted her to rap on it! What, like Lil Kim or something? I have no idea. I don’t know why I would think that she would want to do that.

Yeah so lyrically I feel embarassed and immature about this one. But I like the way the song sounds, and the creative distorted vocal thing. I love the bassline. I used to picture opening a concert with that beat/bassline. That’d be neat. You could walk through the crowd with sunglasses while it played over and over or something. 🙂

The other thing that I was proud of on this one is I did it using just 8 tracks. I think I never mixed this one in the big Ubik studio, I just did it all at home on 8 tracks. Bounced tracks back and forth and such. So that was cool. Hence, I learned a lot doing this song.

Well, love love and love, don’t fuck with “the pair”, y’all! *eyeroll*

Interlude 2: Jumpin Jack

July 11, 2008 by Aaron

Artistic Apocalypse

interlude 2, m.c. murph, nquit music

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Ok well. This is an interlude, since it’s just spoken word. And at that time I didn’t really do spoken word as its own whole thing, so it was an interlude. Man I thought these were so clever *smacks forehead*. I still think the jumpin jack part is kinda funny, but mostly these two poems (there are two) are really embarassing.

But what’s hilarious about the two poems on here is this. In 1996 was it – no I think 1997 – I was qualified for the Albuquerque slam off, because I kept getting 2nd place at the slams while doing sound for the documentary we were shooting (Flaming Tongues I think we called it – or Summon The Fire – see previous blog entry for talk of Matthew John Conley and those two names) for KNME Channel 5 (PBS).

Every month we’d have the poetry slam down at the Dingo Bar in Albuquerque, right on Gold. That became Burt’s Tiki Lounge later. I’d write two new things every month for that (there were two rounds in the slam). They always sucked, were way too short, etc. But Tracy Paris once told me “you own the stage” and I believe she wasn’t puttin me on. I did not, however, own the page, let me tell you. God.

Anyway, I was qualified for the slam off in I guess 97? And I had these two poems picked out as my two poems for the 2 rounds of the slam off (I didn’t even know that maybe the slam off would be different). I thought they would so slay everybody. Well I was a little sick on the day of the slam off, and I skipped it. It really didn’t occur to me as very big a thing. I had no idea how important the slam would become to me later. I really didn’t. It was such an afterthought, and I had no idea there was this nation full of slamming, that it was growing, what a big thing it was to commit to going to nationals, nothing. What I was was M.C. Murph the rapper, and slam was a side issue.

In some sense, that’s what I’m getting back to now, slam and performance poetry maybe being a piece of the pie, but not the whole thing by any means. Nevertheless, it will always be a bigger thing than I realized back then.

Well, I didn’t go that night to the slam off, and that’s probably for the best, because I would’ve gotten shellacked with these two stupid ass “poems”. I didn’t realize that the heavy hitters weren’t slamming when I was getting 2nd with these little things. The slam off would have been Matthew John and Tracy Paris and Danny Solis and stuff – and me saying “this is what i do fuck you!” oh my GOD.

I did do these two poems at a slam some months later, at UNM. A nice cozy intimate fun safe, positive friendly slam. I got shellacked even there doing these two. But they were creative at least. I sat on the floor indian style for Jumpin Jack, and the Fuck You thing has a reference to Kenn Rodriguez and to the first slam poem I ever saw, which is Matthew John Conley’s why mama why poem (I don’t know the title). *sigh*

Man, thinking about it now, I was as bad as any of the kinda stupid people you might see doing poetry slams and making everybody cringe, losing slams left and right. I could name names, but how mean is that? I’m just thinking how blown away I’d be if I went to nationals this year and one of those dudes was 10th in the world all of a sudden. I’d be like “wait what? did I miss something?” That must be how Matthew John Conley felt in 2002 when we’re all in the lobby of the hotel and my name is in the 10th spot, and I’ve made semi-finals. And there he as the elevator pointing at me, grinning with his 13 teeth and quoting me, saying,

“MY DEMONS ARE THE ONES!!!”

m-c-murph

File This

Compression

File Format and Codec

Sample Rate, Bit Depth and Bit Rate

The Big Ones

Other Major Formats

What To Use?

Resources

Change?

Whinerz

Steam

Austin Nights

Interlude 3

Artistic Apocalypse Zen Row Your Boat Mix!

Quietly Manic

The Pair

Interlude 2: Jumpin Jack