How to use Media Alignment Tool

The basics in 60 seconds

You recorded one event on several devices — say two cameras and a voice recorder. Each was started at a different moment, so the same event happens at a different time in each file. This app works out those differences and gives you back files that all start at the same instant.

1. Add your recordings with Add Media.
2. Align them with one button — Align every track.
3. Check by pressing Space to play them all together.
4. Export with the upload-arrow button, and choose a folder.

A few words you'll see throughout the app and this guide:

Track

One recording (one file) in your project. Each track has its own colour.

Timeline

The strip at the bottom where every track is laid out against a shared clock, drawn as a sound wave.

Playhead

The thin vertical line on the timeline showing the moment you're looking at.

Reference track

The recording every other track is lined up against. Usually your best-quality camera or microphone.

Offset

How many seconds after the start of the timeline a track begins. Aligning sets this for you.

Drift

How far a device's clock runs fast or slow, shown as seconds per hour (for example +1.93 s/h). The app corrects it on export.

Marker

A small flag pinned to a moment in a track — placed by the app where it found a match, or by you.

In / Out points

Optional start and end points that limit which part of the event is exported.

1 · Install & first launch

Download the installer for your computer from the download page and open it.

Set up ffmpeg (one click)

The app uses ffmpeg, a free and trusted tool, to read and write audio and video. If your computer doesn't already have it, a window appears the first time you open the app:

2 · A tour of the window

The window is split into three areas, plus a status bar along the bottom.

You can resize the areas by dragging the borders between them, and rearrange them by dragging their title tabs. The app remembers your layout.

3 · Add your recordings

Click Add Media at the top of the Media list (or choose File → Add Media…) and select every recording of the event. You can select several files at once, and add more later.

Other formats that ffmpeg understands usually work too — choose All Files in the file picker.

• A small progress bar appears under each new file while the app reads its sound. This only takes a few seconds for most files.
• Reorder tracks by dragging a file up or down the list. The timeline and video views follow.
• Remove a file from the project with the × beside it. The file on your computer isn't touched.
• "No audio — cannot be auto-aligned" means the file has no sound. You can still line it up using markers or by hand.
• "Previewing via …" means the format can't be played directly (common with AVCHD .mts camcorder files), so the app made a lightweight preview copy. Alignment and export always use your original file.

Joining files a camera split up

Action cameras (GoPro and others) and some camcorders split a long recording into several files of a few minutes each. Join them into one before aligning, using Merge & Add Media.

1. Click Merge & Add Media, then Add Media in the window that opens, and select all the pieces of one recording.
2. Check the order. The app sorts the pieces into recording order automatically (GoPro file names don't sort correctly on their own). If needed, drag them, use the arrows, or click Sort to restore the automatic order.
3. Check the Destination folder and File name for the joined file. The app warns you if the folder doesn't have enough free space.
4. Choose a Method:
   • Quick merge (default) joins the pieces as they are. Fast — about as long as copying the files — with no loss of quality. All pieces must come from the same camera settings.
   • Re-encode creates a completely new file. Much slower, but works even if the pieces differ. The format, resolution, frame rate and quality settings below become available; if pictures have different shapes, choose Fit (black bars), Fill (crop the edges) or Stretch.
5. Leave Keep telemetry and metadata on to carry over GPS and motion data from cameras that record it, where the file type allows.
6. Click Merge and Add Media. When it finishes, the joined file is added to your project. You can cancel at any time and return to the window with your choices intact.

4 · Align automatically

Automatic alignment compares the sound in each recording with the sound in the reference track, and moves each track to where it matches. It works whenever the microphones heard the same things — they don't need to sound identical.

1. Choose the reference track (optional). The first recording with sound is used unless you pick another: click the anchor button on the track's header in the timeline. Pick the recording with the clearest sound, ideally one that runs for the whole event.
2. Click "Align every track" in the timeline toolbar (the button with a zig-zag path, just right of the magnet). To align a single recording instead, click its header to select it, then click the magnet button.
3. Wait a moment. Progress is shown in the toolbar, and can be cancelled with the ×. A few minutes of audio typically takes seconds; long recordings take longer.
4. Read the report that opens when it's done (see below). The timeline zooms out to show the whole, aligned project.

Reading the alignment report

The moments that were matched stay on the timeline as small markers, so you can jump to any of them later and confirm by eye and ear.

5 · Check the result

Play the project and watch and listen: lips should match voices, and claps or door slams should happen at the same moment in every view.

• Play / pause with the middle button or Space. The buttons either side jump back or forward by one frame, 5 seconds or 30 seconds. The menu on the right changes playback speed (¼× to 8×).
• Jump to a moment by clicking anywhere on the timeline, or drag along the time ruler above the tracks to scrub.
• Zoom the timeline with the toolbar buttons, the + / − keys, or by holding Ctrl (⌘ on Mac) and scrolling. Press F to fit everything.
• Jump between markers with , and . to hear the matched moments one after another.

Controls on each track

Click a track's header to make it the active track (highlighted with a bar on its left edge) — buttons like Align active track act on it. Hold Ctrl / ⌘ or Shift while clicking to select several tracks. Drag a header up or down to reorder tracks.

6 · Sync using markers

Use markers when automatic alignment can't find a match: a camera with no microphone, recordings made in different rooms, or very noisy sound. You mark the same real moment in each recording, and the app lines the marks up.

Good moments to mark are short and obvious: a hand clap, a clapperboard, a camera flash, a door closing, a light switching on.

1. Find the moment in the first recording. Click the track's header to make it active, then move the playhead to the exact moment — use ← / → to step one frame at a time.
2. Add a marker with the pin button in the toolbar, or press M.
3. Repeat for each recording, marking the same moment in each. It doesn't matter where the tracks currently sit on the timeline.
4. Click "Sync every track from markers" (the branching icon in the toolbar), or select one track and use Sync active track from markers (chain link).
5. Read the report. For each track it shows how closely the marks agree, for example ±2.1 ms, and warns if one marker is far from the others.

7 · Adjust by hand

You can always move a track yourself — to fine-tune a result, or to place a recording that has nothing to match against.

Dragging on the timeline without Alt selects a stretch of time instead — useful for aligning part of an event or exporting just that part. This keeps you from moving a track by accident.

8 · The video views

Every camera appears as a tile in the Video area. Tiles play in step with the timeline.

• Make all tiles bigger or smaller with the slider at the top right, or the small/large tile buttons either side of it.
• Zoom into one view — to check a detail like a mouth or a hand — by clicking the magnifier-in-a-frame button to unlock adjusting, then:
  • use the tile's vertical slider, or hold Ctrl / ⌘ and scroll (or pinch on a trackpad) over it;
  • drag inside the tile to move around the zoomed picture;
  • drag the tile's bottom-right corner to make just that tile bigger (double-click the corner to return it to the shared size);
  • double-click inside the tile to undo its zoom.
• Click the magnifier button again to lock the views so they can't be moved by accident. The circular-arrow button resets zoom on every view.

Zooming here only changes what you see in the app — it doesn't affect the exported files.

9 · Export

Exporting writes a new copy of each recording, trimmed and padded so that every file starts and ends at the same instant and is exactly the same length. Where a recording hadn't started yet (or had already stopped), the gap is filled with black picture and silence.

Your original files are never changed.

Choose the part to export (optional)

• Whole project — from the earliest start to the latest end of any recording. This is used if you set nothing.
• In to Out — move the playhead and press I to set the start and O to set the end (or use the flag buttons in the toolbar). Clicking near the start or end of a recording snaps the playhead onto it exactly.
• Selection — drag across the timeline to select a stretch of time.

Run the export

1. Click the Export button (upload arrow) in the toolbar, or File → Export….
2. Range: choose the part to export. The most specific one you've set is picked for you.
3. Tracks: all tracks, only the tracks you've selected, or only the active one.
4. Destination: click Browse to choose the folder for the new files.
5. Filename suffix: added to each original name, so Interview.mp4 becomes Interview_sync.mp4. Turn on Overwrite existing files only if you want to replace an earlier export.
6. Click Export. Each file's progress and the time remaining are shown. You can close the window — the export carries on and its progress shows in the status bar. Cancel all stops it.

Format & quality for each track

By default each exported file matches its original — same picture size, frame rate and similar quality — saved as a widely compatible MP4 (H.264 video, AAC sound). You only need these settings if you want something different, such as smaller files or a format for a particular editing program.

Click the sliders button on a track's header to open its settings.

• Copy to applies the same settings to every other track, or to the tracks you've selected.
• Save these settings stores them as a named preset; Apply a preset uses one. Presets are available in every project.
• Reset returns the track to matching its original.

10 · Save your work

A project remembers your recordings, their alignment, markers, In/Out points and export settings, so you can come back to it later.

• Projects are saved as small .valproj files. They point to your recordings rather than containing copies, so keep the recordings where they are (or move the whole folder together).
• Autosave keeps a recovery copy of unsaved changes every 15 seconds. If the app closes unexpectedly, it offers to Recover your work the next time it opens. This never overwrites your saved project.
• The app asks before closing if you have unsaved changes.

11 · Preferences

Open Preferences from the app menu on Mac, or File → Preferences… on Windows and Linux (Ctrl+, / ⌘+,). Changes save as you make them and apply to every project.

12 · Keyboard shortcuts

Shortcuts work while the timeline area is in use — not while a window or text box is open. Press ? in the app to see this list. On a Mac, Alt is the ⌥ Option key.

13 · Troubleshooting

A track wasn't aligned ("left where it was")

• If the recording started more than 5 minutes before or after the reference, raise the Search window in Preferences and align again.
• Make sure the track actually overlaps the reference in time — a recorder that only ran after the reference camera stopped has nothing in common with it. Choose a longer recording as the reference.
• If the sound is very different (another room, heavy wind noise) or missing, sync using markers instead.

The bottom-right corner says "ffmpeg not set up" or "too old"

Click the message and choose Download ffmpeg for me. The app needs ffmpeg version 4.2 or newer.

A video shows black, or "Proxy build failed"

The app couldn't play that format directly and couldn't make a preview copy — often because the folder beside the original is read-only (for example, a camera card). When asked where previews should go, choose Use the app proxy folder. Alignment and export still work either way.

Windows says "Windows protected your PC"

Windows shows this for apps it hasn't seen downloaded many times. Click More info, then Run anyway.

Playing backwards has no sound

That's expected: pressing J steps backwards through the pictures rather than truly playing in reverse.

How do I update?

When a new version is out, a notice appears in the status bar. Click it to read what's new, then Download to open the download page in your browser, and install it over the old version. Your projects and preferences are kept.