Fidelia — Help

High-fidelity audio player for macOS and remote control for iOS. Bit-perfect playback with professional DSP, Audio Unit hosting, and headphone virtualization.

Getting Started

Launch Fidelia. The player window appears — this is your primary interface for transport controls, volume, and track display.
Open the Library with ⌘L or View → Show Library. Drag audio files or folders onto the library window to import.
Double-click any song in the library to begin playback. Use Space to play/pause.
Your library is stored in ~/Music/Fidelia/ and persists across sessions.

Library

The Library stores all your imported audio with metadata, artwork, and playlists. Files are referenced by location — Fidelia does not copy files into its library folder.

Importing Music

Drag & Drop — Drag files or folders onto the library window. Fidelia recursively scans folders for supported audio formats.
File → Import to Library (⌘O) — Open a file picker to select files or directories.

To audition tracks without adding them to your library — for example, listening to client mixes, evaluating new files before keeping them, or playing files from an external drive — see Preview Playlist.

Managing Your Library

Sort — Click column headers (Title, Time, Artist, Album, Format, Sample Rate, Bit Depth, Bitrate) to sort. Click again to reverse.
Show / hide columns — Right-click the column header row to toggle optional columns. Format, Sample Rate, Bit Depth, and Bitrate are hidden by default.
Search — Use the search field to filter by title, artist, album, or genre.
Playlists — Create playlists from the sidebar. Drag songs to reorder within a playlist. Playlists can be organized into folders — see Playlist Folders.
Get Info — Right-click a song and choose Get Info, or press ⌘I, to view and edit metadata. Multi-select before opening for batch edits — see Editing Metadata.
Artwork — Drag artwork onto the album art panel, or use Edit → Find Artwork Online (⌥⌘A) to search automatically.
Delete — Select songs and press Delete to remove them from the library. Original files are not affected.

Relocating Missing Tracks

If you move files to a new location, tracks will appear as offline (dimmed with a warning icon). Use File → Relocate Missing Tracks to point Fidelia at the new folder. It matches files by name and automatically updates all references.

Editing Metadata

Open Get Info on a song with ⌘I or via the right-click menu. The dialog is fully editable for songs imported into Fidelia's library; songs sourced from Music.app are read-only (Music.app is the source of truth there).

Editable fields

Title, Artist, Album, Album Artist, Composer, Genre
Year, Track number, Disc number
Comment

Sample rate, bit depth, bitrate, duration, format, and file location are technical properties of the audio data itself and aren't editable from Get Info.

Apply to all songs in this album

At the bottom of the single-song dialog, the Apply to all songs in this album checkbox expands an edit to every song that shares the current Album and Album Artist. Useful for fixing genre or year across a whole album from one track.

Editing many songs at once

Select multiple songs in the library and open Get Info — a multi-song dialog appears with a subset of fields (Artist, Album, Album Artist, Composer, Genre, Year, Comment). Per-song fields like Title and Track number are hidden because their values aren't meaningfully shared across a selection.

Fields where every selected song already has the same value show that value, ready to edit.
Fields with mixed values render blank with a "Multiple values" placeholder. Type a new value to overwrite across the selection.
Only fields you actually focus or modify get committed — untouched fields preserve each song's existing value, so a quick year-only edit doesn't blank out the rest of the metadata.
A confirmation dialog appears before the first multi-song save (with a Don't ask again checkbox).
Mixed selections that include any Music.app-sourced song are read-only — Fidelia refuses to silently edit a subset.

What Save does

Clicking Save updates Fidelia's library database immediately, then mirrors the new values into the source file's embedded tags off-main:

FLAC — Vorbis Comment block
MP3 — ID3v2 frames at the front of the file
M4A / MP4 / AAC / M4B / M4R — iTunes-style atoms inside the MP4 container
OGG / OGA — Vorbis Comments inside Ogg pages
OPUS — OpusTags inside Ogg pages
WAV / AIFF / CAF — Library-only. Embedded tag formats for these containers aren't widely honored by other audio software, so Fidelia leaves the file alone.

For each format that supports it, Fidelia preserves frames and keys it doesn't manage itself — ReplayGain, MusicBrainz IDs, custom user tags from other editors all survive a Save.

Successful saves are silent. If a file write fails (volume offline, file became read-only, format unsupported), a transient toast appears at the top of the Library window confirming the database edit and explaining what didn't reach the file.

Library access for tag writes

For libraries on external volumes or NAS shares, Fidelia may ask once for folder access the first time you save tags into that location — granting the suggested folder covers every file underneath, persists across launches, and won't ask again for that library. Local libraries imported normally don't trigger any prompt.

Multi-song save progress

Album-scope and multi-song commits below 30 songs run silently in the background. Larger commits show a progress toast at the top of the Library window with a counter and Cancel button — you can dismiss the Get Info dialog while the writes finish. Cancel stops scheduling new writes; in-flight writes complete atomically (already-written files stay written).

If a file write fails: it retries automatically

When a tag write can't reach its file (NAS dropped, volume ejected, permission revoked), Fidelia queues the affected song and tries again on the next launch. Once the volume is reachable, the file gets the database's current values silently — no user action needed.

For the rare case where a queued retry can never succeed (a permanently-removed volume), File → Clear Pending Tag Writes empties the queue manually. The menu item is disabled when nothing is pending.

Playlist Folders

The sidebar supports nested folders for organizing large playlist collections. Folders are containers — they hold playlists and other folders, but never songs directly.

Creating folders

Right-click any blank space in the sidebar's Fidelia section and choose New Folder.
To create a folder inside an existing folder, right-click the folder and choose New Folder in Folder.
The new row opens with its name selected for inline rename.

Organizing

Drag a playlist or folder onto another folder to move it inside.
Drag back to the top level by dropping into the Fidelia section's empty space.
Right-click a playlist or folder and use Move to… for a menu of valid destinations when drag-and-drop is awkward.
Folders show their child-count and a disclosure triangle. Click the triangle to expand or collapse.

Deleting

Right-click a folder and choose Delete Folder. Empty folders delete inline. Folders with playlists or sub-folders inside open a confirmation alert that lists what will be removed.

Music.app folders

With Music.app integration enabled, Fidelia mirrors the folder hierarchy from your Music.app library under the Music section of the sidebar. Music-side folders are read-only — they reflect Music.app's organization and update when Music.app changes.

Preview Playlist

The Preview Playlist is an opt-in scratch space for tracks you want to listen to without adding them to your Library. It's cleared automatically each time you launch Fidelia, so it never accumulates state between sessions.

Useful when you're auditioning client mixes, evaluating promo files before keeping them, or playing tracks from an external drive you don't want referenced in your permanent collection. Each new drop replaces the previous Preview session — Fidelia treats each batch as a new audition.

Turning it on

Open Settings → General → Library and enable Preview Playlist. A new Preview entry appears in the sidebar (under Fidelia, alongside Library) marked with a lightning-bolt icon to signal its ephemeral nature. The row is shown only while Preview has tracks in it; an empty Preview is hidden.

Adding tracks

Hold ⇧ while dragging files onto the Player window, the Mini Player, or the Library list. The drop is routed into Preview instead of being imported.
File → Add to Preview… (⇧⌘O) — File picker that always routes to Preview.

⇧-drag works on Fidelia's own windows. Dropping on the Dock icon, using Open With → Fidelia from the Finder, or double-clicking an associated file always goes to your Library. For preview semantics from those entry points, see Preview-only mode below.

Each Preview drop replaces any tracks already in Preview — drop a list, the list plays from the first track. If a track in the new drop is also currently playing, it restarts from the beginning so the audition session is consistent.

Promoting tracks to your Library

Right-click the Preview sidebar entry and choose Move All to Library to commit the entire Preview session at once. Duplicates against existing Library content are skipped.

Clearing

Preview clears itself at every cold launch — quit Fidelia and reopen it, and Preview starts empty. To clear during a session, right-click the Preview sidebar entry and choose Clear Preview.

Preview-only mode

If your primary use of Fidelia is auditioning rather than collecting — common for mix engineers, A&R, and reviewers — enable Send all incoming files to Preview by default in Settings → General → Library (visible once Preview Playlist is on).

With this mode on, every entry point — drag-and-drop, Open With → Fidelia, Dock-icon drops, and double-clicks — routes incoming files into Preview instead of your Library. Use File → Import to Library (⌘O) for the rare track you want to keep, or hold ⇧ while dragging onto a Fidelia window to import that specific drop.

Preview is a session-local, machine-local concept. It isn't synced via Music.app, never participates in playback history, and isn't visible to Fidelia Remote. Tracks that exist only in Preview disappear at next launch — back up anything you want to keep by promoting it to your Library first.

Playback

Play/Pause — Space
Next / Previous — ⌘→ / ⌘←
Shuffle — Randomizes the playback order within the current queue.
Repeat — Off, All (loops the queue), or One (loops the current track).
DIM (⇧⌘D) — Reduces volume to a preset level without changing the volume knob.
Mute (⌘M) — Silences output instantly. DIM and Mute are mutually exclusive.

Fidelia can run as a clean file-to-DAC path or as a full DSP playback chain, depending on your Output, Audio Engine, HeadSpace, and Advanced settings. Bit-perfect mode bypasses the DSP chain entirely.

When you press pause with effects loaded (reverbs, delays, convolutions), Fidelia lets the plug-in tails decay naturally for up to a few seconds rather than cutting them off — same behavior a DAW would give you on a transport stop. Resume is still instant.

Player Views

Large / Medium / Small / Smaller (⌘1–⌘4) — Four player sizes with progressively compact layouts.
Mini Player (⇧⌘M) — A minimal floating player with transport controls, volume, and track info. Ideal for keeping Fidelia visible while working.
Player On Top (⇧⌘T) — Keeps the player window above all other windows.

Audio Output

Fidelia sends audio to your selected output device using its own playback engine. Configure device selection, hardware sample rate, and routing in Settings → Output.

Device Selection — Choose any connected output device.
Device Rate — Set the hardware sample rate directly when you want Fidelia to hold a specific DAC rate.
Follow file sample rate (DAC) — When enabled, Fidelia switches the DAC to each file's native sample rate whenever the device supports it. This reduces or eliminates SRC.
Channel Routing — For multi-channel devices, a routing matrix lets you map input channels to any output channel. Stereo devices use direct 1:1 routing.
Configure… — Opens macOS Audio MIDI Setup for device-level configuration outside Fidelia.

Bit-Perfect & Exclusive Mode

These options live in Settings → Advanced and control how Fidelia interacts with the output hardware and DSP chain.

Bit-Perfect Mode — Bypasses HeadSpace, dither, SRC, and Audio Units. It also forces file-rate matching so the DAC follows the track whenever possible.
Exclusive Mode (Hog Device) — Takes exclusive ownership of the selected output device. Other apps cannot use that device while Fidelia is holding it.

Sample Rate Conversion (SRC)

When the source file's sample rate does not match the active device rate, Fidelia applies sample rate conversion from the Settings → Audio Engine tab.

Quality — Monitor, Standard, High Fidelity (default), Mastering, and Ultra (Offline).
Presets — Default, Gentle, Steep, Ultra-Steep, Steep No Aliasing, Intermediate Phase, and Minimum Phase give you faster access to the common filter shapes.
Engine — Linear Phase uses the r8brain path. Phase Selectable uses the soxr path with linear, minimum, and intermediate phase options.
Advanced filter controls — Filter Steepness and Cutoff Scaling let you tune the transition band directly when you need a custom filter shape.

Dither

When reducing effective bit depth, Fidelia applies dither from the Settings → Audio Engine tab to preserve low-level detail.

Type — TPDF (recommended), TPDF Hi-Pass, Rectangular, Gaussian, or None.
Noise Shaping — Off, Light (3rd-order), Moderate (5th-order), or Psychoacoustic (default).
Bit Depth — Auto-detect from the output device, or set manually to 16-bit or 24-bit.
Dither Level — Adjusts the added dither level.
Hi-Pass Cutoff — Available for the hi-pass dither types.
Auto-blanking — Silences dither on zero input to avoid noise in quiet passages.
Peak limiting — Prevents clipping when dither raises the signal near 0 dBFS.

HeadSpace

HeadSpace is Fidelia's headphone virtualization DSP. It simulates the spatial characteristics of loudspeaker listening through headphones, reducing fatigue and creating a natural soundstage. Configure it in Settings → HeadSpace.

Crossfeed

Angle — Sets the virtual speaker placement (0°–75°).
Amount — Controls how much of each channel bleeds into the opposite ear.
Reflector — Adds early reflection weight to enhance spatial depth.

Equalization

Treble — Shelving EQ with adjustable gain (±6 dB) and frequency (1–16 kHz).
Bass — Shelving EQ with adjustable gain (±6 dB) and frequency (30–500 Hz).

Per-Band Crossfeed

Fine-tune crossfeed independently for Low (<800 Hz), Mid (800–4k Hz), and High (>4k Hz) bands.

Monitoring

Balance — Left/right balance adjustment.
Mono — Sum stereo to mono for single-speaker or reference checks.
Swap L/R — Swap left and right channels.
Phase — Normal or Inverted (polarity flip on one channel).

HeadSpace is designed for headphone listening only. Disable it when using speakers.

Audio Units

Fidelia hosts Audio Unit (AU) plug-ins in the playback DSP chain. Add EQ, reverb, metering, and other compatible Audio Unit effects for real-time processing.

Enable the AU processing chain in Settings → Advanced.
Load plug-ins from the effect slots on the player. The slot picker groups plug-ins by manufacturer for easier navigation in large collections.
Click a loaded slot to open the plug-in's native UI.
Audio Units are part of Fidelia's DSP path and are bypassed by Bit-perfect mode.

Editor Window

When you open a plug-in's editor, Fidelia adds a thin bar at the top of the window with:

Presets — factory presets exposed by the plug-in, plus your saved user states for that slot.
Enabled — per-slot bypass. Toggles processing without unloading the plug-in.

Editor windows open at each plug-in's natural size. Resizing, where supported, is handled by the plug-in itself inside its view.

Plugin Hosting

Fidelia hosts Audio Unit plug-ins either in-process (loaded directly into Fidelia's own memory, lowest latency, matches Logic Pro and Fidelia 1.x) or out-of-process (routed through macOS's AUHostingServiceXPC sandbox, slightly higher latency, but isolated from Fidelia). The choice is made per slot — manage it in Settings → Plugins.

Per-Slot Hosting Preference

Each slot has a three-way picker:

Auto (default) — Fidelia decides. Sandbox-safe plug-ins and most legacy plug-ins load in-process. Plug-ins known to trigger macOS authorization dialogs on in-process load (certain PACE-protected titles from Moog, Strymon, UADx, UAD, and similar) are detected by a pre-flight scan and routed straight to out-of-process hosting so the dialogs never appear. Covers the vast majority of plug-ins correctly with no user intervention.
Force Out-of-Process — always route this slot through the XPC sandbox, regardless of what Auto would have chosen. Use this for a plug-in that crashes or misbehaves in-process but isn't caught by Fidelia's scanner.
Force In-Process — always load directly into Fidelia's process, regardless of what Auto would have chosen. May trigger macOS authorization dialogs for PACE-protected plug-ins — approving them unlocks the plug-in. Use this if a scanner-flagged plug-in appears silent or bypassed when hosted out-of-process.

Settings → Plugins

The Plugins pane shows a row per effect slot with:

The plug-in currently loaded in that slot (or (empty)).
The slot's live hosting mode — In-process or Out of process (XPC). Reflects where the plug-in actually ended up after routing, which may differ from the user preference when Auto is selected.
The hosting picker — Auto, Force Out-of-Process, or Force In-Process.

PACE / iLok-Protected Plug-ins

Plug-ins from Moog, Strymon, UAD, UADx, and other PACE- or iLok-protected vendors need special runtime privileges to load in-process. With Auto (the default), Fidelia's pre-flight scanner detects these plug-ins and routes them straight to out-of-process hosting on first load — no authorization dialogs appear.

If you set a slot to Force In-Process and load a PACE-protected plug-in into it, macOS may present one or more one-time authorization dialogs (for example, a Lower Security Settings dialog or a PACE licensing alert). These are macOS / PACE prompts, not Fidelia errors. Approving them unlocks the plug-in and the dialogs won't appear again for that plug-in.

Hosting preference is per slot, not per plug-in. If you swap a different plug-in into a slot, the new plug-in inherits the slot's setting. For most users, leaving every slot on Auto is the right choice — Fidelia's scanner handles PACE-protected plug-ins correctly without user intervention.

Switching a Loaded Plug-in's Mode

Changing the picker takes effect on the next plug-in load in that slot.
After changing the picker, remove and re-add the plug-in (or relaunch Fidelia) for the change to apply.
A plug-in that works one way may behave differently the other way. If a plug-in sounds bypassed or silent after switching, try the opposite mode.

Format Conversion

Right-click songs in the library and choose Convert Format… to convert between formats.

Output Formats — FLAC, Apple Lossless (ALAC), AAC, WAV, AIFF, CAF.
Sample Rate — Optionally resample to any standard rate (22.05–192 kHz).
Bit Depth — 16-bit or 24-bit for PCM formats. Dither is applied automatically when reducing depth.
AAC Bitrate — 64–320 kbps for AAC output.
Replace Original — Optionally move the source file to Trash after conversion.

Metadata (title, artist, album, artwork, etc.) is preserved in converted FLAC and M4A files. WAV and AIFF output does not include metadata. To edit metadata after import, see Editing Metadata.

DSD & APE Import

Fidelia automatically converts DSD (.dsf) and Monkey's Audio (.ape) files to Apple Lossless (ALAC) on import. The converted files play natively; original files are kept alongside.

Title, artist, album, album artist, genre, track number, disc number, and embedded artwork are read directly from the source files at import time — DSD via the embedded ID3v2 metadata chunk, APE via the APEv2 footer — and carried through to the converted ALAC output.

Fidelia Remote (iOS)

Control Fidelia from your iPhone or iPad over your local network. The free companion app shows your library, now playing info, and full transport controls.

Install Fidelia Remote from the App Store.
Ensure both devices are on the same Wi-Fi network.
Fidelia Remote discovers the Mac automatically via Bonjour — no configuration needed.

Music.app Integration

Enable Music.app integration in Settings → General to browse your Apple Music library directly in Fidelia. Songs, playlists, and artwork are imported read-only.

Keyboard Shortcuts

Play / Pause	`Space`
Next Track	`⌘→`
Previous Track	`⌘←`
Import to Library	`⌘O`
Add to Preview Playlist	`⇧⌘O`
Toggle Library	`⌘L`
Toggle Mini Player	`⇧⌘M`
Player On Top	`⇧⌘T`
Large / Medium / Small / Smaller	`⌘1` – `⌘4`
DIM	`⇧⌘D`
Mute	`⌘M`
Find Artwork Online	`⌥⌘A`
Get Info (selected song[s])	`⌘I`

All shortcuts are customizable in Settings → Commands.

Supported Formats

Lossless — FLAC, ALAC (M4A), AIFF, WAV, CAF, SD2, AU, W64
Lossy — AAC (M4A), MP3, OGG Vorbis, Opus
DSD — DSF (auto-converted to ALAC on import)
Monkey's Audio — APE (auto-converted to ALAC on import)

Troubleshooting

No audio — Check your output device in Settings → Output. Verify the device is connected and not muted at the hardware level. If using Exclusive Mode, ensure no other app has locked the device. If Bit-perfect mode is on, remember that Fidelia will bypass the DSP chain and force file-rate matching.
Library empty after relaunch — The library is stored in ~/Music/Fidelia/. If this folder is missing or permissions were changed, Fidelia cannot persist data. Verify the folder exists and is writable.
Tracks show as offline — Files were moved or the volume is disconnected. Use File → Relocate Missing Tracks to update references, or reconnect the drive.
Music.app library not loading — Ensure Music.app integration is enabled in Settings → General. Grant Fidelia access to your music library in System Settings → Privacy & Security → Media & Apple Music.
Tag-write permission dialog appears — On the first save into a library on an external volume or NAS share, Fidelia asks once for folder access. Granting access here covers every file underneath and persists across launches; you won't be asked again for that library. If you cancel, the database is still updated but the file's embedded tags aren't — re-Save and grant access to retry.
"Saved to library. File could not be updated…" toast — The database edit landed but Fidelia couldn't reach the source file (volume offline, file moved or read-only, format unsupported). Fidelia automatically queues the song and retries on the next launch when the volume is reachable. For permanently-removed files, use File → Clear Pending Tag Writes to empty the queue manually.
Audio Unit not appearing — Ensure the plug-in is installed in ~/Library/Audio/Plug-Ins/Components/ and passes AU validation. Restart Fidelia after installing new plug-ins.
Plug-in shows an authorization dialog on first load — This is a one-time macOS or PACE prompt for PACE- / iLok-protected plug-ins. Usually shouldn't appear in normal use — Fidelia's pre-flight scanner catches these plug-ins and routes them out-of-process automatically. If you see a dialog, you likely set the slot to Force In-Process; approving the dialog unlocks the plug-in, or set the slot back to Auto in Settings → Plugins.
Plug-in fails to load, crashes Fidelia, or shows authorization errors despite being licensed — Set the slot to Force Out-of-Process in Settings → Plugins, then reload the plug-in. This routes it through Apple's XPC host and often works around plug-ins that misbehave in-process.
Plug-in sounds silent or bypassed despite showing its UI — A few plug-ins don't work correctly under out-of-process hosting. Set the slot to Force In-Process in Settings → Plugins, reload the plug-in, and approve any authorization dialogs that appear.
Plug-in appears silent or bypassed — Some plug-ins behave differently in- and out-of-process. Open Settings → Plugins, switch the slot's hosting mode, then reload the plug-in.
Gapless playback gaps — Gapless playback works with all supported formats. If you hear gaps, the source files may have silence encoded at track boundaries.

Contact Support

Questions, feedback, or bug reports — reach us at support@audiofile.engineering