Bad File Detection

Radio automation depends on every file in your library being a real, playable audio file. A zero-byte file, a truncated download, or a corrupted encode can cause dead air, skipped songs, or unexpected silence in the middle of a broadcast. Librarian watches for these problems so you can fix them before they reach the airwaves.

What Gets Flagged

Librarian flags a file as potentially bad for any of the following reasons:

Too small: The file's size on disk is below the minimum file size threshold set in Preferences. The default is 8 KB — far smaller than any legitimate audio file, but large enough to catch empty, near-empty, and truncated files.
Unreadable audio: The file exists and is above the size threshold, but macOS cannot read it as audio. This usually means the file is corrupted, incomplete, or not actually an audio file despite having an audio extension.
Zero or invalid duration: The file can be opened as audio, but reports a duration of zero, infinity, or not-a-number. This typically indicates a damaged header or an encoding problem.

When the Check Runs

Bad file detection happens in two places:

On every library reload — Each time Librarian loads the library (at launch, after an import, or when you press ⌘R), it does a quick size check on every file. Files below the minimum size threshold are flagged immediately. This check is fast because it only reads file metadata, not the audio data itself.
During Song Lengths detection — When you run Song Lengths from the Import tab, Librarian probes every file for its actual audio duration. This deeper check catches files that are large enough to pass the size check but contain no usable audio. Any file that fails the size check, the duration check, or the readability check is flagged.

The Bad Files Message

When bad files are found, a panel appears over the waveform area with a sand-colored background and dark red text. The heading reads:

"The following files appear to be bad, damaged, or empty. Remove them?"

Below the heading you will see:

A Select All checkbox that toggles every file in the list at once.
A scrollable list of the flagged files, each showing its full path with a checkbox. All files are checked by default.
A Delete Selected button that permanently removes the checked files from your hard drive and then reloads the library, which automatically clears the deleted entries from the database.
A Dismiss button that closes the panel without deleting anything, in case you want to investigate the files yourself first.

⚠️

Deleting is permanent. When you click Delete Selected, the files are removed from disk — not moved to the Trash. Make sure you've reviewed the list before confirming. If you're unsure about a file, uncheck it and investigate it manually.

Adjusting the Minimum File Size

The size threshold is configurable in Preferences. Look for the Min file size field, where you can enter a number and choose either KB or MB from the dropdown. The default of 8 KB is a good starting point — a half-second mono MP3 is already about 9 KB, so anything below 8 KB is almost certainly not a usable audio file.

If you work with very short sound effects or micro-clips, you might want to lower this value. If your library only contains full-length songs, you could raise it (for example, to 50 KB or even 100 KB) to catch more marginal files.

💡

The size check catches the most obvious problems instantly on every library load. For a thorough check that also tests whether files contain valid, decodable audio, run Song Lengths detection from the Import tab.

Why This Matters for Automation

AutoCast trusts the library. If a file is listed in the database, AutoCast assumes it can play it. A zero-byte file or a corrupted MP3 in the rotation means dead air — the worst thing that can happen on a radio station. By catching these files in Librarian, you're preventing problems before they ever reach the broadcast chain.