Cutting vertical video

Your Program Monitor shows the whole 1080×1920 frame with nothing on top of it. TikTok, Reels and Shorts do not. By the time your cut is on a phone, a caption block, an action rail, a progress bar and a tab bar are sitting on top of the picture — and the lower third of the frame you carefully composed is mostly covered. PreviewMonitor puts that chrome back on, at the correct scale, on the actual class of screen the audience will use.

This guide covers the loop: set the sequence up, pick the right layout, make the mock realistic enough to trust, read the safe zones, and save a framed still to send to the client.

Set the sequence up first

The plugin streams whatever Premiere Pro's Program Monitor renders, at the sequence's own frame size — the phone is told the source dimensions and frame rate directly, and the layouts key off that aspect ratio. So the sequence has to be vertical before any of this reads correctly.

Pick the layout

Tap the grid button in the top HUD to open the layout picker. Portrait only — the picker is hidden in landscape, because the platform mocks are portrait-authored artwork and there is nothing sensible to draw in landscape.

The picker only ever expands one group at a time, and the caption editor is the last row rather than a separate HUD button.

Each platform group opens to three variants: LTR (default), RTL and Both. LTR is the right-handed rail every one of these apps ships in English. RTL is the mirrored version — Arabic and Hebrew feed layouts move the action rail to the left edge, so a title parked at the left of the frame that reads fine in LTR can be buried in RTL. Both draws the rail on both edges at once and centers the caption, which is the fast way to find a composition that survives either.

Reach for the layout you are actually publishing to. They are not interchangeable: the three platforms put their rails at different heights, and Shorts has fewer engagement counts than TikTok because the dislike and share icons carry no number.

How the picture is fitted

The platform layouts follow what the real apps do. A source that is exactly 9:16 or taller fills the video area and is cropped slightly at whichever axis overflows; a source wider than 9:16 — square, 4:5, 16:9 — letterboxes with bars, exactly as a landscape clip reads inside a portrait feed.

That crop is the point when you are checking coverage, and a nuisance when you are checking framing. Universal Safe Zone letterbox-fits instead, so the whole frame stays visible and the guide lines register with the real frame edges.

Make the mock realistic

A mock with placeholder text is a mock you stop believing. The caption block, the profile photo and the engagement counts are all live SwiftUI text drawn over the video — not baked into the artwork — so you can put your real caption in and see whether it eats the shot.

Open the layout picker and tap Edit Profile & Caption at the bottom. The row only appears for layouts that actually draw a caption, so it is absent under Standard, Full Screen and Universal Safe Zone.

Every field writes through immediately — there is no Save button, and the values persist across app launches.

• Profile name — the handle above the caption. Defaults to PreviewMonitor.
• Caption — the description block. It is capped at five lines on all three platforms, which is itself the thing worth checking: paste your real caption and see where it truncates.
• Profile photo — tap the avatar for Choose from Library, Choose from Files or Remove photo. Picking one opens a Move and Scale cropper; Use Photo commits it. On TikTok the photo also replaces the avatar in the action rail, with the follow badge redrawn on top.
• ENGAGEMENT — Likes, Comments, Saves, Shares, Reposts. Free-text, so 5.2M and 1,672 both work. One shared set across platforms; each layout renders only the counts it has icons for.

Reset to defaults puts all of it back, including the photo.

The caption block sits at the same place on every platform: bottom-anchored, clear of the progress bar, hugging the leading edge in LTR and the trailing edge in RTL, centered in the Both variants.

Read the safe zones

The Universal Safe Zone is one full-frame guide over the whole picture, symmetric so it covers LTR and RTL together. Selecting it expands two controls:

• Opacity — a slider with a magnetic detent at the 30% default. Drag past the catch band to break free of it.
• Color — red, black, white, green or blue. The overlay is drawn as a template and recolored, so it stays crisp at any tint.

Use the platform layouts to answer "does the UI cover this", and the Universal Safe Zone to answer "will this survive everywhere". They answer different questions — the platform mocks show you one app's real geometry, the safe zone shows you the intersection.

Save a framed still

The download button in the top HUD writes the current frame to Photos, with whatever layout is active composited in.

What you get depends on the layout:

• Standard — the raw decoded program frame at its full decoded resolution. No canvas resampling, no overlay.
• Any other layout — a WYSIWYG composite at your screen's size and scale: the video placed in the layout's video rect with the same fit-or-fill rule the live view used, then the chrome, caption and counts rendered on top.

So a still saved under TikTok LTR is a picture of your shot inside a TikTok frame, complete with your caption — which is the thing to AirDrop to a client who is arguing that the title is fine where it is.

The glyph swaps to a checkmark and a Saved to Photos toast appears for about a second and a half.

The first save asks for photo access. PreviewMonitor requests add-only permission, which is the lighter prompt — it can write to your library but never read it.

Resolution while you work

Resolution Limit lives on the HUD chip — the button showing the current rung, next to the gear — not in the settings panel. The default is 720p and it is marked Recommended in the menu.

For layout work 720p is more than enough: you are judging where things sit, and the picture is being displayed on a phone. Raise it when you switch to judging detail; see Judging picture on the phone for what that costs on each platform.

What is Pro in this workflow

Live streaming itself is free and there is no connect-time paywall. Full breakdown: Free vs Pro.

Related

• Layouts — every layout and control in detail
• Save frame — what exactly gets composited
• Live view — the HUD, zoom, and chrome behavior
• Encoding settings — Resolution Limit, codec, GOP