The audiobook checker can now fix your files for ACX
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R. S. Breed Founder
The audiobook file checker used to tell you what ACX would reject. Now, for the problems that are safe to fix automatically, it fixes them: https://bervet.com/tools/audiobook-file-checker
Drop your chapter files in as before. If any fail ACX's checks, you get a "Fix for ACX" button. It:
- sets the volume to -20 dB RMS, the middle of ACX's -23 to -18 range
- holds the peaks under -3.5 dB, only on the moments that are too loud, so the rest of the chapter is untouched
- gives each file 1 to 5 seconds of room tone at the start and end, using your own room tone copied from the file, never digital silence
- saves it as a 192 kbps constant-bit-rate MP3 at 44.1 kHz, which is ACX's format
- makes everything mono if your files are a mix of mono and stereo (ACX wants them all the same)
Then it checks each fixed file again, and you can listen to it before you save it.
What it won't touch, because it needs your ears: background noise, long pauses inside a chapter, clicks and mouth noise. Turning up a quiet recording turns its noise up too. If that would push the noise over ACX's -60 dB limit, it tells you instead of pretending it passed.
Files that already pass are left alone. Re-encoding an MP3 loses a little quality, so if you have your WAV masters, fix those.
It all runs in your browser and nothing is uploaded. Free for members. Works best on a computer: a long chapter takes a minute or two.