The master you keep

WAV, 44.1kHz, 16-bit, mono or stereo, one file per chapter, named in order. This is the copy you never throw away. Every future edition — a new storefront, a new format, a corrected chapter — is cut from it, not from a compressed file.

Never archive MP3 as your master. Compression is a one-way door: what it discards cannot be recovered, and a second compression on top of the first is audible even to untrained ears.

The editions you ship

MP3, constant bitrate 192kbps or higher, is the common retail edition. M4B is the chaptered audiobook container Apple prefers — one file that remembers where the listener stopped.

Most storefronts want each chapter as its own file, with a short head and tail of room tone rather than a hard cut, plus an opening and closing credit file. Peak levels below -3dBFS, loudness held near -18 to -20 LUFS mono, noise floor beneath -60dBFS: those three numbers are what a retailer's automated check actually measures.

What this house delivers

Every audio book built here is delivered as chaptered masters plus the retail editions, laid in a sealed vault the author reaches from their own chamber. The stems — voice, effects and score kept apart — are delivered too, so a future edition never has to be rebuilt from scratch.

An audio book is priced as arithmetic: 7.000000000000001% of your word count. A 90,000-word novel is $6,300, and the delivery specs above are included, not billed as extras.

Asked and answered

Do I need separate files per chapter?

Yes. Nearly every storefront requires it, and it is also how a listener navigates. One long file is a delivery that will be rejected.

What loudness should an audiobook be?

Around -18 to -20 LUFS with peaks under -3dBFS and a noise floor below -60dBFS. Those are the figures automated retailer checks measure.

Should I keep the stems?

Always. Voice, effects and score kept apart mean a single line can be re-recorded later without rebuilding the whole book.