About ChapterPass

Why ChapterPass Exists

Narrators and indie authors submit audiobooks to ACX and other distributors every day, only to have them rejected for technical reasons they cannot easily diagnose or fix. The ACX requirements cover eight separate technical checkpoints: RMS loudness, true peak levels, noise floor, sample rate, channel count, file format, head silence, and tail silence.[1] Meeting all eight consistently across every chapter of an audiobook is tedious, repetitive work that requires specialised knowledge and tools most narrators do not have.

Giovanni built ChapterPass from direct experience with audiobook mastering. After years of processing chapters by hand and seeing the same rejection patterns repeat across clients, he designed a deterministic engine that handles all eight checkpoints automatically. The goal is straightforward: narrators upload their chapters and download files that pass ACX's technical review on the first submission.

How ChapterPass Works

ChapterPass automatically masters your audiobook chapters to meet all 8 ACX compliance checkpoints. Your audio never leaves your device, and the same input always produces the same output, so results are fully reproducible.

The engine adjusts loudness to the required range, limits peaks below the -3 dBFS ceiling, manages noise floor below -60 dBFS, converts to the correct output format, and adds the required silence padding. Every output file is verified against all eight checkpoints before it can be downloaded. For a complete breakdown of terms, see the audiobook mastering glossary.

Who Uses ChapterPass

ChapterPass is built for anyone who needs audiobook files to meet ACX technical specifications. That includes solo narrators recording in home studios, indie authors producing their own audiobooks, and small publishers managing multiple titles at once. Some users are experienced audio professionals who want to skip the repetitive mastering step. Others are first-time narrators who have never opened a DAW and need a reliable path from edited recording to submission-ready files.

The common thread is practical: these users have clean, edited recordings and need the final technical mastering handled correctly. They do not want to learn signal processing or buy expensive plugins for a task that has fixed, measurable targets. ChapterPass replaces that entire step with a single upload, and the same output files work on ACX, Findaway Voices, Authors Republic, and Google Play Books.

Sources

1. ACX Audio Submission Requirements