Every Audio Format You'll Actually Run Into (And the Two That Aren't Audio)

First, an uncomfortable question: do you know what's inside your files?

I was helping a coworker export a recording last week. He said, "just save it as an mp3," which was fine, so I asked whether it was going out to a platform or staying as his own archive. He blanked.

That blank look is the norm. For most people, audio format means one word: mp3. As long as it plays.

But the range here is wilder than that. Two files both called "audio" can be an untouched waveform, a voice recording squeezed to almost nothing, a file that contains no sound at all but a set of instructions, or — my favorite — something that isn't even a file, just a pointer on a disc.

So let's walk through them by what's actually inside. No glossary recital.

1. The foundation: two camps

Before any names, keep this:

One camp is "real sound" (it stores a waveform). The other is "not really sound" (instructions, an index, something else entirely).

The first camp splits again into the uncompressed heavyweights (WAV, AIFF, PCM) and the compressed ones (MP3, AAC, FLAC, OGG and friends). The second camp is MIDI and CDA — files that look like audio and aren't.

Get that skeleton in your head and every format below lands in a slot immediately.

2. The heavyweights: WAV and AIFF

WAV — universal, and huge

Microsoft's format, built on RIFF. The usual arrangement is raw PCM waveform data with a header of about 44 bytes in front that says: 44.1 kHz, 16-bit, stereo, read it like this.

Every piece of software accepts it, from a recording studio to CapCut, from Windows Media Player to FFmpeg. And since it isn't compressed, quality is as high as the source.

The problem is one syllable: big. Thirty megabytes for a song is normal; a long podcast session can run into gigabytes.

That makes its job clear: WAV is a working format, not a sharing format. Record to WAV, edit, then export MP3 or AAC. That pipeline hasn't meaningfully changed in twenty years.

AIFF — the Apple version

Apple's equivalent, same idea: uncompressed waveform, or Apple Lossless if you ask for it. Anyone working in Logic on a Mac sees it constantly.

If you're Windows-only, you may never touch it. But when a Mac colleague sends you a .aiff, don't panic — it's the same tier as WAV, just convert and move on.

3. The compressed camp: lossy and lossless, separate roads

This is where the names pile up and people get lost, so I'll split it in two.

🔥 Lossy: MP3, AAC, WMA, plus OGG, RA, AMR and SPX

• MP3: MPEG Audio Layer III. The philosophy is blunt — if your ear won't miss it, cut it. The file drops by 80 to 90 percent; 128 kbps is acceptable, 320 kbps is hard to fault. The cost is real: detail is gone, and re-encoding degrades it further. It's the original delivery format and still plays on everything
• AAC: the successor, with a smarter algorithm — better sound at the same rate, smaller files at the same quality. TikTok, YouTube, Apple Music, iPhone recordings and ringtones (.m4r) are all AAC underneath. If MP3 is the past, AAC is the present
• WMA: Microsoft's Windows Media Audio, aimed at beating MP3. It does hold up at low bit rates and the files are small, but it lost the ecosystem fight. Fine when you meet one, nobody chooses it, and it's a bad delivery format
• OGG (Vorbis): the open-source darling. Ogg is the container, Vorbis the codec inside, no licensing fees. Game sound effects and open-source projects still use it, though AAC and Opus have taken most of the web
• RA (RealAudio): a period piece. Dial-up era, played while downloading, quality scaled to your connection. Purely archaeological now
• AMR / SPX: voice specialists. AMR is what phone calls, MMS messages and old Android recordings used, at 4.75 to 12.2 kbps — intelligible speech in a few dozen KB. Speex (SPX) is the open VoIP equivalent. Play music through either and it turns to mush

💎 Lossless: FLAC, APE and ALAC

All three share a promise: decode it and you get the original back, byte for byte, at roughly 30 to 40 percent less space than WAV.

• FLAC: open, universally supported, the default for archiving. This is what most serious libraries are made of
• APE (Monkey's Audio): compresses slightly harder, but the software ecosystem is small and support is inconsistent. New projects go FLAC
• ALAC: Apple's lossless, the "Lossless" tier in Apple Music. Seamless on Apple gear, less so outside it

Truthfully: on a $30 pair of Bluetooth earbuds, you probably can't tell FLAC from a 320 kbps MP3. Don't fill a drive over the word "lossless." Let the situation decide.

4. The fakes: MIDI and CDA

These two need their own section because they fool people constantly.

MIDI — it's a score, not a sound

Musical Instrument Digital Interface. What's stored is instructions: which track, which instrument, which note, how hard, how long. A few minutes of music fits in a few kilobytes, and you can stack dozens of tracks.

Playback means your sound card or a software synth performs the score live. So what you hear is synthesized instruments — no vocals, no recorded performance.

It's for arranging, old ringtones, game music and keyboard practice. Just remember it isn't a recording, and don't send it to someone expecting a song.

CDA — the file that isn't

If you've opened a CD on a computer, you've seen a folder of .cda files, one per track, looking entirely legitimate.

They aren't. CDA is an index pointing at "track three starts here" on the disc. Drag it to your desktop and you get a few dozen kilobytes that won't play, because the audio is still on the disc's Red Book track.

To keep a digital copy you have to rip it — EAC, Audition, anything that does the job — into WAV or FLAC. I have watched people copy that icon so many times. Please stop 😮💨

5. DTS: the home-theater heavy artillery

DTS (Digital Theatre Systems) is playing a different game: multichannel surround.

It isn't competing on how big a song is. It handles the 5.1 and 7.1 mixes in movies, Blu-rays and games — the plane crossing from left to right, the explosion behind your head. Stereo MP3 cannot do that job.

If you own a soundbar, a receiver or a Blu-ray player, "DTS-HD MA" on a disc means high-spec lossless surround. Irrelevant for a podcast, unavoidable if you're mixing surround or building a theater.

6. One table, then you're done

Format	What's inside	Lossy?	Size	Use it for
WAV / AIFF	Waveform, usually PCM	No	Huge	Recording, editing, masters
MP3	Compressed audio	Yes	Small	Sharing, phones, podcasts
AAC	Smarter compression	Yes	Small	Streaming, video audio, Apple
WMA / OGG	Compressed audio	Yes	Small	Don't pick these on purpose
FLAC / ALAC / APE	Losslessly compressed	No	Large	Archives, critical listening
AMR / SPX	Speech-only compression	Yes	Tiny	Calls, voice memos, VoIP
MIDI	Score instructions	—	Tiny	Arranging, ringtones
CDA	Track index	—	Not a file	Rip the disc instead
DTS	Multichannel surround	Varies	Large	Theater, Blu-ray, games

Are there more? Endlessly — Opus, AC3, M4A, AU, VOC, well over a hundred in total. Nobody knows them all. Look one up when it shows up.

The short version

Choosing a format is choosing what to give up:

• Quality, or anything you'll edit later → the heavyweights (WAV / FLAC)
• Sending, posting, saving space → the slim ones (MP3 / AAC)
• Just intelligible speech → extreme compression (AMR)
• Immersive surround → the heavy artillery (DTS)
• You see .cda or .mid → ask whether it's sound at all

Get that straight and you stop producing moments like "I exported a 400 MB WAV and can't send it" or "I copied the CDA files and nothing plays."

When you do need to convert, Audio Converter handles the usual formats with the bit rate under your control, and Video Converter pulls audio out of a video. Everything runs in your browser: no uploads, no retention. Your privacy is fully protected.

That's it. I'm going to compress this morning's WAV into AAC and drop it in the edit, because my drive is nearly full 🫠

Common questions

How many audio formats are there really?

Well over a hundred once you count Opus, AC3, M4A, AU, VOC and the rest, and nobody memorizes them. The useful move is to sort by what's inside: real sound that stores a waveform, versus files that store instructions or an index. Then split by lossy, lossless and speech-only. Anything unfamiliar, look it up when it crosses your desk.

What's the difference between WAV and AIFF?

Almost nothing that matters. WAV is Microsoft's, built on RIFF; AIFF is Apple's; both usually carry uncompressed PCM at maximum quality and equally enormous size. The difference is ecosystem: WAV dominates on Windows and in editing software, AIFF shows up on Macs and in Logic. Converting between them is trivial.

FLAC, APE or ALAC for storing music?

FLAC, unless you live entirely inside Apple's ecosystem, where ALAC is fine. FLAC is open, plays nearly everywhere, saves 30 to 40 percent over WAV and decodes byte-identical. APE compresses slightly harder but its tooling is thin, and ALAC is smooth on Apple gear and patchy elsewhere. New archives should just be FLAC.

Why won't CDA files copied off a CD play?

Because CDA is only an index telling the player where each track starts, with no audio inside it, and those files are usually a few dozen kilobytes. The sound is still on the disc's Red Book tracks. Use ripping software to export WAV or FLAC; copying the icon is the single most common way to waste an afternoon.

Note: some of the material here was produced with AI assistance.

---

---