Spongefork / ShadowTag

Processing & Analysis

Automatically detect loudness, tempo, musical key, sound keywords, and UCS categories.

Overview

ShadowTag can analyze audio files and fill in their metadata fields for you. All analysis runs locally on-device — no internet connection required.

Running the analysis is free. Results are pending edits, like any other, until you save. Writing them into the files themselves requires ShadowTag Pro.

Analysis tools are available in the Tools menu and apply to the currently selected files. Multiple files can be processed at once. Most tools open an options dialog first, where you can also choose between the selected files and the whole playlist.

Loudness

Measures integrated loudness according to the broadcast loudness standard and writes the result to the file's metadata.

  • Five loudness measurements are written: integrated loudness, loudness range, true peak, max momentary loudness, and max short-term loudness.
  • Integrated loudness is measured in LUFS (Loudness Units relative to Full Scale). Surround files are measured by their declared channel layout.
  • A file with several audio tracks is measured on the track selected for it. Ogg Vorbis, Opus, Matroska and MXF files can be measured too.
  • Run from Tools > Detect Loudness… (⌘⌥L).
  • Options: Choose where results are written — the loudness tags, the BEXT loudness fields of WAV and FLAC files, and ReplayGain track gain and peak. With ReplayGain on, Album Gain Across All Files measures every file of the run as one album and writes album gain and peak to each. Opus files get the R128 gain tags their format defines instead of ReplayGain tags. Skip Measured Files leaves out files that already hold every chosen value. When files have a pending trim, fade or normalize, Pending Edits chooses whether the edited audio is measured (Render) or the file as it is on disk (Ignore).

Tempo (BPM)

Detects the tempo of the audio and writes it to the BPM metadata field.

  • Works best on rhythmic content with a clear beat.
  • Run from Tools > Detect Tempo (⌘⌥T).
  • Options: Set a minimum and maximum BPM range to constrain the detector (useful for half-time or double-time ambiguity). Choose a quality preset — Fast, Balanced, or Accurate — to trade speed for precision. A Decimal Places option controls how much fractional precision is written, for tempos that aren't whole numbers.

The detected BPM is also used by the metronome and bar-number ruler during playback.

Musical Key

Detects the musical key (pitch class and tonality) of the audio and writes it to the Key metadata field.

  • Outputs a key such as C Major or F# Minor.
  • Run from Tools > Detect Pitch (⌘⌥P).
  • An options dialog lets you configure the analysis before it runs.

Video: BPM, Loudness & Key Detection — includes verifying detected tempo against the built-in metronome.

Sound Keywords

Classifies the audio content and generates descriptive keywords using on-device sound recognition. Results are written to the Keywords metadata field.

  • Examples: piano, outdoor ambience, crowd noise, gunshot.
  • Run from Tools > Detect Keywords (⌘⌥K).
  • Options: Set a Minimum Confidence threshold — only results above this level are kept. Choose an Assignment mode: Merge adds new keywords to any existing ones; Replace overwrites them.

Tools > Organize Keywords… (⌘⌥⌃K) tidies the keyword list of the selected files or the whole playlist, removing duplicates. Its options set the letter Case (title case, lowercase or unchanged), whether keywords are Sorted alphabetically, and whether underscores are Replaced with spaces. Detect Keywords offers the same three rows and shares their settings, so newly detected keywords are organized the same way.

UCS Category Detection

Suggests Universal Category System (UCS) categories based on the file name, its tags, and its BEXT and iXML text.

  • Writes to the UCS Category and Subcategory fields.
  • Run from Tools > Detect UCS Category.
  • Review and confirm suggestions in the UCS tab of the Metadata panel before saving.
  • After detection, the chosen category and subcategory are also synced into the iXML USER fields for Soundminer compatibility.

Video: Keyword & UCS Detection in ShadowTag — confidence thresholds, merge vs. replace, and the UCS naming preview.

UCS Rename

ShadowTag can rename selected files to the UCS filename convention (CatID_FXName_CreatorID_SourceID_UserCategory_UserData) using their UCS metadata. The dialog offers two modes:

  • Copy to Folder — Writes renamed copies to a chosen destination folder, leaving the originals in place.
  • Rename in Place — Renames the files in place. References in every playlist that pointed to those files are updated automatically.

In both modes, the FX Name Source setting chooses where the FX Name part of the new filename comes from:

  • Filename — Uses the existing filename stem.
  • Title — Uses the file's Title metadata field.
  • iXML FXName — Uses the FX Name field from iXML USER.

A live preview shows the resulting filenames as you adjust source and other options. If the chosen source is empty for a file, the renamer falls back to the full filename stem.

Batch Processing

All analysis tools can run on multiple files at once. Select the files you want to process (or use ⌘A to select all) before choosing a tool from the Tools menu.

A progress sheet shows while a tool runs; Cancel stops it.

Audio Edits

Non-destructive audio editing tools — fade, trim, crop, and normalize — apply edits to playback in real time without modifying the source file. The dirty column shows a waveform icon for files with pending audio edits. Saving the edits back into your files requires ShadowTag Pro; see the Playback page for the waveform handles and live preview. Trimming applies to video files as well as audio; fades and normalize do not.

  • Fade Selection (⌥F) — Apply fade-in and fade-out across the current selection.
  • Fade with Options (⌘⌥F) — Open a dialog to set fade durations and independent taper shapes for fade-in and fade-out. The taper picker offers preset curves plus a Custom slot that persists across sessions. A zero-second duration clears the fade.
  • Crop Selection (⌘I) — Bound playback to the current selection.
  • Detect Trim Points (⌘⌥I) — Scan for silence at the start and end of each file and propose trim boundaries automatically.
  • Normalize with Options (⌘⌥N) — Open a dialog with Peak or LUFS mode and a target level; the corresponding gain is applied non-destructively.
  • Clear Fades (⌥⇧F), Clear Trim (⌥⇧I), and Clear Normalize (⌥⇧N) reset their respective edits.
  • Clear Audio Edits (⌥⇧⌫) — Clear all pending audio edits at once, reverting playback to the file's original state without saving.

Segment Detection

For files that contain several distinct sounds back to back, ShadowTag can find the individual sounds and split them into separate files.

  • Detect Segments (⌘⌥X) — Scan the file for non-silent regions. The proposed regions appear first as pending markers you can drag by the handles to fine-tune; choose Write Markers to commit them, or Esc / Cancel to discard. A "Detecting…" label shows while the scan runs.
  • Render Segments (⌘⌥⇧X) — Split the file into individual audio files at those marker boundaries. Requires ShadowTag Pro.
  • Clear Segment Markers — Remove the segment markers without splitting. If a pending detection is showing, this drops the pending markers; otherwise it clears the committed ones.

Segment regions can also be placed by hand in the editor with Create Segment Marker — see Markers under Playback.

The Segment Detector panel controls how regions are found — silence threshold, gap bridging (how short a gap between sounds to ignore), minimum region length, and pre- and post-roll padding around each region. The Render Segments panel holds the options for the render step. Both remember their settings between sessions. The Segment Detector panel also has a presets menu — save the current settings, recall a saved preset, or reveal the preset file in Finder.

Detection can run across many files at once: the Segment Detector panel offers a multi-file mode that processes the selected playlist files together, with progress and a cancel button.

Video: Non-Destructive Audio Editing in ShadowTag — normalize, trim, fades, and segment detection on a real sound library.

Audio Format Conversion

ShadowTag can convert audio files to different formats. Select files and choose File > Export > Convert Files (⌘E) to open the conversion options. Available output formats include WAV, AIFF, MP3, FLAC, OGG (Vorbis or Opus), CAF, and M4A. Long WAV exports are written as RF64, so they can pass 4 GB.

For a file carrying more than one audio track, conversion uses the track chosen in Editor > Audio Track — see Playback.

Conversion options include:

  • Output format and codec
  • Sample rate and bit depth
  • Mono/stereo channel count
  • MP3 bit rate
  • Metadata copy behavior: Copy All, Copy Text Based, Copy Markers, Copy Text and Markers, or Ignore
  • File conflict handling (Overwrite Files, Rename Uniquely, or Show Errors)
  • Group By Tag — Output to a flat folder, or organize into subfolders by one or two tag keys (e.g. Category/Subcategory). Tag values that already contain / are split into nested folders automatically.
  • Render Audio Edits — Choose Render to apply any pending non-destructive edits (trim, fade, normalize) to the exported files, or Ignore to skip them. Remembered between exports.
  • Presets — The presets menu saves and recalls the format, sample rate, bit depth or bit rate, channels, metadata copy, overwrite choice, audio edit handling and Group By Tag. Whether to convert the selection or the whole playlist, and the destination folder, are chosen each time.

After a conversion, ShadowTag offers to add the converted files to a playlist.

Export Soundpack

Packages a selection of files into a self-contained soundpack folder. Choose File > Export > Soundpack (⌘⌥⇧E) and pick a mode:

  • Copy — Duplicates the source files into the soundpack as-is.
  • Move — Relocates the source files into the soundpack and updates any playlists that referenced them.
  • Convert — Runs the files through audio format conversion on the way out, using the same options as Convert Files, including the Metadata copy behavior choice.

The destination can be a flat folder, or a one- or two-level subfolder hierarchy grouped by tag values — the same Group By Tag behavior used by Convert Files. A Render Audio Edits option applies any pending non-destructive edits (trim, fade, normalize) to the exported files; choose Render or Ignore. Last-used settings are remembered between exports.

Export CSV

File > Export > CSV (⌘⇧E) writes a playlist's metadata to a spreadsheet file, one row per file.

  • Selection or whole playlist — The dialog exports the whole playlist by default; switch to the current selection with Use Selection.
  • Metadata — Only Tags With Content includes just the columns that hold a value in at least one exported file. All Metadata includes every file property, tag, BEXT and iXML field, filled or not.
  • Columns follow the order of the file list's columns, so arranging them in View > Organize Columns arranges the spreadsheet. Custom tags that only some files carry are added at the end.
  • If files have unsaved edits, ShadowTag offers to save them first, so the spreadsheet matches what is written in the files.

To copy a few rows instead of writing a file, use Copy > Tags (CSV) in the file list's contextual menu — see Metadata.

Export FCPXML

File > Export > FCPXML writes the selection or the whole playlist as a project that Final Cut Pro, Logic Pro and DaVinci Resolve can import, with each file on its own lane. Files are prepared the same way a spot prepares them — see Spot to Timeline. The dialog offers:

  • FCPXML Version — The document version to write. Choose an older one for an older release of the receiving application.
  • Sample Rate — Leave files at their own rate, or convert any file at another rate first.
  • Pending Edits — Render pending trims, fades and normalize into the exported audio, or ignore them. Shown only when files in the export have pending edits.
  • Files — Leave in Place references each file where it is; Copy All copies the files beside the project.
  • Clips — Top Level places the files directly in the project's timeline; Compound Clip gathers them into one compound clip.

Broadcast Wave files keep their recorded start time. To paste into an open Final Cut Pro project instead of writing a file, use Copy > FCPXML in the file list's contextual menu and press ⌥V in Final Cut Pro. Both require ShadowTag Pro.

Export Artwork

File > Export > Artwork (⌘⌃⇧E) saves each file's embedded artwork into a folder you choose, named after the audio file and kept in its original image format. It works on the selection or the whole playlist, and files that fail are listed when the export finishes.

Video: Export & Convert Files in ShadowTag — sound pack export, Group By Tag, and CSV export.

Pro Features

All analysis and detection tools (loudness, tempo, pitch, keywords, UCS) are available in the free version with no file count limit. Non-destructive audio editing (fade, trim, crop, normalize) is also free to preview and audition. ShadowTag Pro is required for: creating and switching projects, writing metadata to files (⌘⌥S), writing audio edits back to files, audio format conversion, Soundpack export, rendering detected segments, spotting to other applications, FCPXML export and copy, VST-XML copy, CSV export, copying tags as CSV, artwork export, removing embedded artwork, and UCS filename rename.

Edits are kept in your project either way; with ShadowTag Pro, saving writes them to the files.

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