Voxbound / Help / Player profiles and the file check

Player profiles and the file check

A profile sets the audio format for the player you use, and after every merge Voxbound checks the finished file against it. This page lists what each profile sets and checks, and what each message from the check means. It describes Voxbound 4.1.13.

The profiles

Pick the profile under Profile in the Output card (click Change to open it). Generic M4B is the default, and choosing MP3 output switches to MP3 Fallback. Choosing a profile sets Quality back to 128k, so choose the quality after the profile.

What each profile sets and checks
Profile	Audio	Also checked
Apple Books	AAC, 44.1 kHz stereo, up to 256 kbps	Codec, sample rate, chapters, cover, title
Audiobookshelf	AAC, 44.1 kHz stereo, up to 192 kbps	Codec, sample rate, chapters, cover, title
Prologue	AAC, 44.1 kHz stereo, up to 256 kbps	Codec, sample rate, chapters, title
Generic M4B	AAC, keeping the sources' sample rate and channels (the highest, if they differ)	Codec
MP3 Fallback	MP3, keeping the sources' sample rate and channels (the highest, if they differ)	Codec

If Quality is above a profile's limit, it's lowered to the limit. The Apple Books, Audiobookshelf and Prologue profiles always re-encode the audio, so for a mono recording or AAC files you'd rather not re-encode, use Generic M4B. Our guide to the best M4B settings for each player explains what each player needs.

The check after every merge

Whatever the profile, Voxbound checks that:

the file is the type its extension says: an M4B holding AAC audio, or an MP3 holding MP3 audio;
it has an audio stream and isn't empty;
the audio decodes: 8 seconds are decoded at six points through the book, from the start to the end, to catch damaged audio.

Then it checks what the profile asks for, from the table above. When the merge finishes, the Export complete window shows the file's codec, bitrate, sample rate, channels, chapters, title tag and cover, then either Validation passed or a list of Validation warnings.

What the messages mean

Messages from the check, and what to do
Message	What to do
No chapter markers found (required for …)	The file has no chapters. You'll usually see this when checking a file Voxbound didn't make. Merge the book again as M4B, which gives it chapters.
No cover art embedded (recommended for …)	Choose an image in the Cover card, or use Look up in the Book card, and merge again.
No title tag (required for …)	Fill in Title in the Book card and merge again.
Sample rate … Hz (expected 44100 Hz)	Usually seen when checking a file Voxbound didn't make. Merge the book again with the profile, which converts the audio to 44.1 kHz.
Codec … does not match the … profile (aac)	The file isn't AAC. Merge it again as M4B with the profile.
File is a … container, not m4b (wrong extension?)	The file has been renamed: for example, an MP3 renamed to `.m4b`. Merge it again as M4B instead of renaming it.
Audio codec is … (expected aac for m4b)	The container is right but the audio isn't AAC. Merge it again as M4B.
The audio is damaged and won't play properly around …. Merge the book again.	The file's audio didn't decode at the times shown. Merge the book again. If it happens again, see damaged audio.
No audio stream found in output file.	Check the source files play, then merge again.
Output duration is 0 — file may be empty.	Check the source files play, then merge again.
Could not read output file — may be corrupt.	Merge again. If it keeps happening, email support with the log.

Checking a file you already have

On the Repair & verify tab, click Choose file… under Verify a file, pick a profile and click Run verification. The same check runs, and you get the same messages.

The same tab has Repair a file, which rewrites an M4B without re-encoding it and saves the result as a new file, named …_repaired.m4b unless you change it. In 4.1.13 the new file doesn't keep the original's tags or cover, and has no chapters unless you give it a list from the Chapters tab. Keep the original, or merge the book again instead.