How to tag podcast episodes and audiobook MP3s so they play in order
The first audiobook I ripped for the car played chapter one, then chapter ten, then eleven through nineteen, and only then chapter two. I was twenty minutes into the wrong end of the story before I noticed. The files were fine. The tags weren't.
Spoken-word MP3s have one job music doesn't: play in a fixed order, and keep that order after being copied to a USB stick, a phone, or a car stereo designed before podcasts existed. Six tag fields do the job.
Why chapter 10 plays before chapter 2
A player sorts an album by track number if the files have one. If they don't, it falls back to sorting by title, and it sorts the title as text. Text sorting compares one character at a time. "Chapter 10" against "Chapter 2": the first eight characters match, then it compares "1" with "2", and "1" wins. So chapter 10 lands before chapter 2, and 11 to 19 pile in behind it. It's the same reason a file manager lists file10.txt ahead of file2.txt.
Two fixes, and I do both. Put a track number on every file, so the player never needs the fallback. And zero-pad the number in the title, Chapter 02 rather than Chapter 2, so a player that ignores track numbers still sorts the text correctly. Padding costs nothing and rescues the cheap car stereos that only ever look at the title.
Which field gets what
The fields are the ordinary ones. What goes in them is different from a music album.
- Album is the show name or the book title, identical on every file, down to the capitalisation.
- Artist is the host, or for a book the author or the narrator. Pick one rule and keep it across the whole set. If half the files name the author and half name the narrator, a player that groups by artist splits your book in two.
- Title is "Episode 12: The one about lighthouses" or "Chapter 03 Low Tide". Padded number first, description after.
- Track is
12/40: this file's number, a slash, the total. Players sort on the first number; the second is only there so they can show "12 of 40". - Year is the release year of the episode, or of the edition you own.
- Comment is a one-line description, or the episode's URL so someone who finds the file later can find the show.
The first four decide the play order. The long version of what every field is for is in tag fields explained. Here's the pattern on three consecutive chapters. Notice how dull the Artist and Album columns are. Dull is the goal.
| Title | Artist | Album | Track | Year | Genre |
|---|---|---|---|---|---|
| Chapter 01 Arrival | Anna Mercer | The Quiet House | 1/38 | 2019 | Audiobook |
| Chapter 02 The Letter | Anna Mercer | The Quiet House | 2/38 | 2019 | Audiobook |
| Chapter 03 Low Tide | Anna Mercer | The Quiet House | 3/38 | 2019 | Audiobook |
A podcast is the same table with the words swapped: the show in Album, the host in Artist, "Episode 12: …" in Title, and 12 in Track.
For a podcast that's still going, leave the total off and write the track as plain 12. Otherwise every new episode means re-tagging all the old ones to bump the total.
Multi-disc audiobooks
A book ripped from CDs arrives as one folder per disc, and every disc starts counting from track 1 again. Put all of it under one album and the player interleaves the discs: every track 1, then every track 2. It's the chapter-10 problem wearing a different hat.
ID3 has a proper answer, a Disc number field (the frame is called TPOS), and a player that understands it sorts by disc first and track second. The editor on editmp3tags.com doesn't have that field. The workaround is better anyway: number the tracks continuously across the whole book. Disc 1 gets 1 to 29, disc 2 carries on at 30, and the last track of the last disc is 87/87. A plain track number works on everything. Disc numbers only work on players that read them, and the rest will interleave your book exactly as before.
Genre is free, so set it
The extended ID3v1 genre list has "Audiobook" at code 183 and "Podcast" at code 186. Some players read the genre and file spoken-word in its own section, away from the music, which is where you want it: nobody needs chapter 14 of a thriller coming up on shuffle at a barbecue. Many players ignore genre entirely. Setting it is one click and hurts nothing. The full list, with codes, is in the ID3v1 genre list.
Cover art on every file
Put one square image on every file, not only the first. Players show art per track, not per album, so a book with art on chapter 1 alone shows the cover for twenty minutes and a grey placeholder for the remaining eleven hours. Same picture, all 38 files. How large to make it is in album art size; remember it's copied into every file, so a huge one costs you 38 times over.
Podcast apps don't read tags
A podcast app never looks at your ID3 tags. It reads the show's RSS feed, and the episode title, description, artwork and order all come from there. Tag the files perfectly and the app won't notice. Leave them blank and it won't notice that either.
Tags matter the moment someone plays the MP3 directly: a listener who downloaded it from your site, a USB stick in a car, a shared folder at work, a cheap player with no internet. If you hand out episodes as files, that's who you're tagging for. They won't thank you, but they also won't email asking why episode 3 is called final_mix_v2.
MP3 or M4B
Audiobook apps on phones tend to prefer M4B files. An M4B is the whole book in one file with chapter markers inside, so the app shows a chapter list, remembers your place and skips a chapter without juggling 38 separate files. For one of those apps, build an M4B.
An M4B only plays where M4B is supported, though. A folder of well-tagged MP3s plays on an old car stereo, a Linux laptop, a player from the petrol station, and anything else with a USB socket. That's why my own books stay as MP3: it's the version that works no matter what I plug it into.
One file or forty
The editor at editmp3tags.com works on one file at a time, in the browser, with nothing to install. That's right for the job it's built for: the stray episode with the wrong track number, the chapter someone renamed, the two files out of forty that don't match the rest. Open the file, fix the fields, download it, done.
It's the wrong tool for tagging a 40-file audiobook from scratch. Forty files one at a time is forty rounds of the same edits. For that, use a desktop batch tool. Mp3tag on Windows and macOS, or Kid3 on any desktop OS, will select all forty, set Album and Artist in one go, and run a "number tracks in order" action that fills in 1/40 through 40/40 in the order the files are listed. It's a couple of minutes, most of which is checking the order. I've compared the options in MP3 tag editors compared.
That checking matters. A batch numbering action numbers files in the order the tool shows them, and if the tool is sorting by title, you'll bake chapter 10 in ahead of chapter 2 and make the problem permanent. Sort the list by filename, confirm chapter 2 is second, then press the button.