Core concepts: zero point, offsets, and the two modes

This is the most important chapter in the manual. None of it is obvious from looking at the interface, and everything else in the app makes sense once these ideas do. If you read only one chapter, read this one.

The problem: files that don’t start together

You have three camera files of one race. The cameras were switched on at different times, so:

• head-on.mp4 starts 12.4 seconds before the gates open.
• side.mp4 starts 15.0 seconds before.
• back-straight.mp4 starts 9.8 seconds before.

“Five seconds into the file” therefore points at a different real-world moment in each one. Press play on all three at once and they show three different parts of the race. To watch them as one, the app has to be told how they relate — and that is what the zero point and offsets are for.

The zero point

The zero point is one moment of the event that you can see in every angle. For racing the natural choice is the start — the instant the gates open — because it’s unambiguous and visible from every camera.

You mark the zero point once. From then on the shared timeline calls that moment 0:00. Times before it don’t exist on the shared timeline (it can’t go negative); times after it are “so many seconds into the race”, regardless of which file each camera recorded.

Exactly one tile carries the zero-point designation, shown by a “ZERO PT” badge in its corner. That tile’s position defines where 0:00 sits. The first video you load gets the designation automatically; you can move it later with the Set Zero Point button.

Offsets

Each video’s offset is simply how far into that file the zero point falls. In the example above the offsets are 12.4 s, 15.0 s and 9.8 s. The app stores one offset per tile.

The whole trick is one line of arithmetic. On the shared timeline, at shared time P, the app shows each tile at:

file position = offset + P

At P = 0 each tile sits on its own zero point (all three showing the gates opening). At P = 5 each tile is five seconds past its own zero point (all three showing the same five-seconds-into-the-race moment, from three cameras). Because every tile advances from its own offset, they stay locked together no matter where you move.

You don’t type offsets in. You park each tile on the shared moment by eye in Unlock Mode, and the app works the offsets out for you when you switch to Lock Mode. More on that below.

The two modes

The app is always in one of two modes, and the two buttons at the far left of the transport bar switch between them.

Unlock Mode — the tiles are free. Each tile has its own independent timeline. The transport bar drives only the selected tile (red border). You use Unlock Mode to load videos and to line them up. Only one tile plays at a time, and you hear the selected one.

Lock Mode — the tiles are one group. Every tile moves together on the shared timeline, each at its own offset. Play, pause, scan, step and the slider act on all of them at once. You use Lock Mode to review. The app opens in Lock Mode, and it’s where you spend most of your time.

Switching modes never changes what any tile is showing. Whatever frame each video is on, it stays on it across the switch. The mode changes only how the controls behave — ganged together, or free — not where the videos are.

What the time display means in each mode

This difference trips up new users, so it is worth stating plainly:

• In Unlock Mode, the time display is the selected tile’s own time — position and duration of that one video file. Select a different tile and the numbers change to that file’s timeline. It is a per-video clock.
• In Lock Mode, the time display is the shared timeline: time since the zero point, where 0:00 is the start of the race, not the start of any file. It’s the same clock no matter which tile is selected, because in Lock Mode selection only chooses which tile you hear, not which one the clock follows.

So the same on-screen “0:03.50” means two different things depending on mode: in Unlock, 3.5 seconds into the selected file; in Lock, 3.5 seconds into the race. Chapter 8 covers timecodes in full, including the clipboard copy.

Setting it up: the golden rule

You never set offsets by hand. Instead:

Line up every tile on the same real-world moment in Unlock Mode, then switch to Lock Mode. The switch does the maths.

When you enter Lock Mode, the app looks at where each tile is currently parked and captures its offset from that. Park them all on the gate jump, lock, and every offset is correct at once. The only tile you treat specially is the zero-point tile, whose position you fix deliberately with Set Zero Point — its offset is the one value you own, and the app never rewrites it behind your back.

Worked example: aligning three angles of a race

Three files: head-on.mp4, side.mp4 and back-straight.mp4. The whole workflow, start to finish.

1. Load the videos. Switch to Unlock Mode. Click Add Video(s), select all three files. They fill three tiles; head-on.mp4 (the first) gets the ZERO PT badge.

2. Find the start in the first angle. Click tile 1 to select it. Scrub the slider until you’re near the gate jump, then use +1f / -1f to land on the exact frame the gates open. Frame-accurate is the point — take the two seconds to step onto the precise frame.

3. Mark it. Click Set Zero Point. Tile 1’s current position is now its offset, and 0:00 is defined. (Tile 1 already held the badge; if you preferred to anchor on a different angle, selecting that tile and pressing Set Zero Point would move the badge there.)

4. Find the same moment in the other two angles. Click tile 2. Scrub and step to the identical instant — the same frame of the gates opening, seen from the side camera. Leave it parked there. Repeat for tile 3.

You do not press Set Zero Point for tiles 2 and 3. Just park each one on the moment. (Only if you wanted a tile to become the anchor would you press the button on it.)

5. Lock. Click Lock Mode. The app reads where each tile is parked, computes every offset, and from now on the three angles move as one. The timeline reads 0:00 with all three tiles showing the jump.

6. Review. Play. Pause anywhere — all three angles freeze on the same instant. Step backward frame by frame through an incident, watching it from three directions at once. Scan at 2× or 4× to move quickly.

7. Save it. Fill in the track, date and race number in the toolbar, then Save Package (chapter 9). Next week, Open Package brings all of this back exactly as it is now.

Fixing a slightly-off alignment

Watching in Lock Mode, suppose the side angle looks one frame late on the line. Switch to Unlock Mode, click that tile, step it -1f, and switch back to Lock Mode. The switch recaptures its offset from the corrected position. One frame fixed, nothing else disturbed. This unlock-nudge-lock loop is the everyday way to touch up alignment.

The fine print

• If you seek the zero-point tile to before its own zero point and then lock, the timeline can’t go negative — the app clamps to 0:00, snaps that one tile forward to its zero point, and says so in the status display.
• The zero-point tile’s offset is only ever changed by Set Zero Point — it’s yours. Every other tile’s offset is recaptured automatically at each switch into Lock Mode.
• A tile whose footage starts after the zero point, or ends before the others, simply rests on its first or last frame while the shared time is outside its range, then joins in when the timeline reaches it.
• If the tile holding the badge is closed, the badge passes to the first remaining video (its offset is not touched).
• In Lock Mode, clicking a tile changes only which tile is audible (and gives it the blue border). The shared timeline is unaffected.