Import Module

Stereo to mono conversion

Not every stereo file contains stereo audio. During import, fMusic analyzes the actual content of every stereo file, classifies it, and converts it according to the rule you set for each case. Nothing is guessed from the file name: the verdict comes from the audio itself.

The three verdicts

fMusic measures the RMS level of the left channel, the right channel, and the difference between them against a fixed threshold of roughly −80 dBFS. There is no sensitivity control to tune: the threshold is part of the analysis, not a setting.

• Fake stereo (mono content): the difference between the two channels is below the threshold. Both channels carry the same audio, so the file is mono in disguise.
• Hard-panned left or right: one channel is below the threshold, so all the content sits on the other side.
• True stereo: the two channels genuinely differ. True stereo is never converted.

A file whose channels are both silent gets no verdict and no conversion: nothing is done to it.

.L/.R pairs are merged first

Stereo material sometimes arrives as two separate mono files. fMusic recognizes pairs named .L/.R and _L/_R and merges them before classification, so they are judged on their content like any other stereo file. Surround sets and space-separated names (like "Gtr L") are not treated as pairs.

Your original files are never touched: the merged copy is written to a temporary folder and carries the pair's base name, so the track Pro Tools creates is named after it. In Organize, where the pair already lives in the session, the merge is performed inside Pro Tools as part of the job instead.

Per-case rules, set once

Each verdict has its own row in Settings > Import & Organize > Stereo-to-mono, with a default chosen to do the right thing:

• Stereo file, mono content: Convert (Mono Sum) by default. Also available: No Conversion, Mono Left, Mono Right, Split Stereo.
• Hard-panned L: Mono Left by default, keeping the channel that carries the content. Also available: No Conversion, Split Stereo.
• Hard-panned R: Mono Right by default. Also available: No Conversion, Split Stereo.
• Split Stereo, stereo content: a .L/.R pair whose content is genuinely stereo becomes one interleaved stereo file, Convert (Interleaved Stereo), by default. Also available: No Conversion.

There is no master on/off switch. As the panel itself puts it: "Always on: set a row to 'No Conversion' to leave that case alone. True stereo and mono are never touched." With every row on No Conversion the content analysis is skipped entirely; pair merging stays active because it is decided by the file names, not by the audio.

Verdicts stay visible

Every conversion is shown as a badge on the track's row in the routing table of the Session Settings page: → Mono (L+R), → Mono (L), → Mono (R), or → Split. There are no silent conversions: if a file was folded to mono, the badge tells you which rule did it.

The same logic at both entrances

The editor's Add Track button runs the same pipeline as the import drop: pair merging, content classification, and your per-case rules. One set of rules covers both entrances, so a file behaves identically no matter how it entered the session.

Why it matters

• Disk space: a mono file is half the size of a fake stereo file carrying the same content twice.
• Routing: mono tracks route correctly to mono buses and channels, instead of occupying stereo paths for mono content.
• Phase: duplicated and one-sided channels invite phase correlation issues later in the mix.
• Session hygiene: the session reads honestly. A track shown as stereo is actually stereo.