Splitting a multi-angle file

Some footage arrives as a single file with the camera angles recorded back to back — angle 1 plays, then angle 2, then angle 3, all in one video. To review those angles side by side you first need them as separate files, one per tile. This app can do that split for you, inside the app, without any external editing tool, and without ever changing the original file.

Why split inside the app

The alternative is to open a video editor, find each boundary by hand, export each angle, and hope the cuts are clean. That is slow, and a careless export re-compresses the video and softens it. The built-in split is different in two ways that matter:

• It is lossless and near-instant. The angles are copied out exactly as they are, with no re-encoding, so even a long file splits in a second or two and every frame is bit-for-bit the original.
• It never touches the source. The new files are written alongside it; the original stays exactly as it was. A wrong boundary costs you nothing — reload the original and mark again.

Once the angles are separate files they behave like any other videos: you set the zero point and align them exactly as in chapter 3. Nothing about Lock Mode, packages, or the timeline changes — that is the whole point of splitting into real files rather than carrying angle boundaries around forever.

Where the buttons are

Two buttons, Mark Split and Cut to Files, sit in the transport bar just after Set Zero Point, set off by thin dividers. They appear in Unlock Mode only — on the main window and on the floating transport window alike.

The workflow

Splitting is three stages: load the file, mark the boundaries, cut.

1. Load the multi-angle file on its own. In Unlock Mode, open the concatenated file as the only video (chapter 5). The feature works on one file at a time, so if anything else is loaded, close it first.

2. Mark where each angle ends. Scrub to the point where the first angle finishes and the next begins, then click Mark Split.

The mark is not placed at the exact frame you are on. It snaps back to the nearest clean cut point at or just before your position — usually within a second or two. A clean cut point is a frame the video can be cut on instantly and without re-compressing; cutting anywhere else would force the app to re-encode. You do not need to find these points yourself — mark roughly where the angle changes and the app moves the boundary to the nearest clean one for you. The status display reports both where you clicked and where the mark actually landed:

Repeat for each boundary. A file with two angles needs one mark; three angles need two; four angles need three. Three marks is the maximum, because four segments already fills every tile.

3. Cut. Click Cut to Files. The app writes one file per segment beside the original, named after it: race.mp4 becomes race_angle1.mp4, race_angle2.mp4, and so on. It then loads angle 1 in place of the original and the remaining angles into the next empty tiles, in order — so the tiles read angle 1, 2, 3, 4 from the first tile onward.

From here it is the ordinary alignment workflow: pick the zero point, park each angle on it, and lock (chapter 3).

Rules and details

A few things worth knowing before you rely on it:

• One video at a time. Both buttons need exactly one loaded video. Load a second and they grey out — but your marks are kept, and the buttons come back if you close the extra video again. Marks are only discarded when you close the file they belong to, and they clear automatically after a successful cut.
• Clearing marks by hand. Right-click Mark Split and choose Clear all marks to start the marks over without reloading.
• Marks go in order. Each mark must be later than the one before it. A mark at the very start of the file, or a second mark that lands on the same clean cut point as an earlier one (two clicks within the same short span), is rejected with a note in the status display rather than making an empty segment.
• Existing files. If a _angleN file of the same name is already there, the app asks before overwriting it.
• If a cut fails. You get an error message, any half-written files are removed, and the original file stays loaded, so nothing is lost.
• The original is safe, always. Splitting only ever reads the source. Marked the wrong spot? Reload the original and mark again.

ffmpeg required. Splitting uses the same ffmpeg tool as Fast Seek (chapter 11). If it is not installed, the app tells you and does nothing else. Appendix 18 walks through installing it and adding it to the Windows PATH.