vertify

Flip 16:9 ↔ 9:16 video without cropping.
The whole frame stays. Blurred or solid bars fill the rest.

Install · Quick start · CLI · GUI · How it works · FAQ

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Social platforms want 9:16. Your camera, screen recording, or talk is 16:9. Cropping throws away half the picture. vertify letterboxes instead: the original frame is scaled to fit, and the empty space is filled with a blurred copy of the same clip (the look used by Reels / Shorts / TikTok) or a solid color.

Landscape in → 9:16 out. Portrait in → 16:9 out. Or force a direction.

Flip Stage GUI — drop a clip, preview the letterbox, export.

Why vertify

	Crop to 9:16	Manual ffmpeg	vertify
Keeps the whole frame	No	If you write the filter	Yes
Blurred background bars	DIY	Long filter_complex	--fill blur
Solid color bars	DIY	pad= + color	--fill color --color white
Auto landscape ↔ portrait	No	Probe first	Default
Dry-run the exact command	No	You are the command	--dry-run
Desktop preview	No	No	vertify-gui

You still need ffmpeg only if you build from source. Official installers and release zips already include ffmpeg and ffprobe next to the Vertify binaries.

Install

Every push to main publishes a GitHub Release with Windows installer, portable zip, and macOS/Linux archives (ffmpeg included).

Windows (recommended)

1. Download VertifySetup-*-windows-x64.exe from the latest release.
2. Run the installer. It puts Vertify in %LOCALAPPDATA%\Programs\Vertify (no admin prompt) together with ffmpeg.
3. Launch Vertify from the Start menu, or run vertify in a terminal if you left PATH checked.

Portable option: unzip vertify-*-windows-x64.zip and keep vertify.exe, vertify-gui.exe, ffmpeg.exe, and ffprobe.exe in the same folder. Double-click vertify-gui.exe. Do not scatter those files.

ffmpeg is bundled. You do not need winget install ffmpeg.

macOS and Linux

Download the archive for your CPU from the latest release, unpack it, and run ./vertify-gui or ./vertify. ffmpeg is inside that folder.

# example — the folder name includes the crate version and short commit
tar -xzf vertify-v0.1.1-b55faf1-macos-arm64.tar.gz
cd vertify-v0.1.1-b55faf1-macos-arm64
./vertify-gui

Move the whole folder somewhere stable (e.g. ~/Applications/vertify) rather than copying a single binary.

From source (Rust)

Building with Cargo does not vendor ffmpeg. Install it yourself, or point Vertify at a folder that contains ffmpeg / ffprobe:

# macOS
brew install ffmpeg

# Ubuntu / Debian
sudo apt install ffmpeg

# Windows (winget) — only needed for cargo/source builds
winget install Gyan.FFmpeg

cargo install --git https://github.com/daylennguyen/vertify --locked
# or
git clone https://github.com/daylennguyen/vertify.git
cd vertify
./install.sh          # Unix
.\install.ps1         # Windows

Unix prefix install (default ~/.local/bin) also expects ffmpeg on PATH:

make install

Override the search path: VERTIFY_FFMPEG_DIR=/path/to/ffmpeg-bin vertify talk.mp4.

Shell completions

# bash
vertify --completions bash > /etc/bash_completion.d/vertify
# zsh
vertify --completions zsh  > "${fpath[1]}/_vertify"
# fish
vertify --completions fish > ~/.config/fish/completions/vertify.fish
# PowerShell
vertify --completions powershell >> $PROFILE

Checked-in copies live in completions/.

Quick start

# Auto: 16:9 in → 9:16 out (talk_vertical.mp4)
#       9:16 in → 16:9 out (talk_horizontal.mp4)
vertify talk.mp4

# Force vertical, social-style blur
vertify talk.mp4 --to 9:16 --fill blur

# White bars, 4K-class long edge, fastest encode
vertify talk.mp4 --fill color --color white --size 3840 --fast

# Plan as JSON without encoding
vertify talk.mp4 --to 9:16 --json-plan

# See the ffmpeg command without running it
vertify talk.mp4 --dry-run

Open the GUI:

vertify-gui
# or
cargo run --release --bin vertify-gui

CLI

vertify [OPTIONS] <INPUT> [OUTPUT]

If OUTPUT is omitted, vertify writes <stem>_vertical.mp4 or <stem>_horizontal.mp4 next to the input.

Flag	Default	Description
-t, --to <auto|9:16|16:9>	auto	Target aspect. auto flips orientation. Aliases: vertical, horizontal
-f, --fill <blur|color>	blur	Empty-space fill
--size <px>	1920	Long edge of the output canvas (1920 = 1080p-class)
--color <name/hex>	black	Bar color for --fill color (black, white, red, green, blue, gray, or #RRGGBB)
--blur <n>	40	Box-blur radius for --fill blur
--preset <preset>	—	x264 preset (ultrafast…placebo), overrides --fast
--crf <n>	21	x264 quality (lower = better; 18–28 is the usual range)
--fast	off	ultrafast preset (larger file)
--output-dir <dir>	—	Directory for autogenerated output files
--suffix <text>	—	Extra suffix for autogenerated output name
-y, --overwrite	off	Replace an existing output file
--audio-mode <copy|aac|none>	copy	Copy audio, force AAC, or drop audio
--audio-bitrate <rate>	192k	AAC bitrate for aac mode and copy fallback
--start <time>	—	Seek into the source before encoding
--duration <time>	—	Encode only the specified duration
--map-metadata	off	Copy source metadata into output
--loglevel <quiet|error|warning|info>	warning	ffmpeg log verbosity
--ffmpeg-arg <arg>	—	Pass extra ffmpeg args (repeatable)
--no-faststart	off	Disable +faststart
--dry-run	off	Print the ffmpeg command; do not encode
--json-plan	off	Print resolved conversion plan as JSON and exit
--open	off	Open output file after successful encode
--completions <shell>	—	Write completions to stdout (bash, zsh, fish, powershell, elvish)

Notes:

• Square input requires an explicit --to 9:16 or --to 16:9.
• If the input already matches the target aspect, vertify warns and re-encodes.
• Audio is stream-copied. If the container rejects that, the encode retries with AAC at 192 kbps.
• Output is H.264 (libx264) in MP4 with +faststart for web playback.
• Canvas dimensions are forced even so x264 is happy.

vertify --help
vertify --version

GUI (Flip Stage)

A small desktop app for people who want to see the letterbox before committing an encode.

cargo run --release --bin vertify-gui

• Drop a clip onto the phone frame, or click / press O to open.
• The stage shows a letterboxed preview (blur or solid fill).
• Click the frame (or Enter / Space) to export.
• Open ··· (or ,) for target, size, quality, color, and dry-run. Esc closes it.
• Shift+? opens a keyboard shortcuts panel.
• Backstage includes custom long-edge input, target swap, reset-to-defaults, and richer color presets.
• If Dry Run is on, use Copy command to copy the exact ffmpeg command.
• After export, use Open folder to open the output directory.
• Hover any control for a tooltip. The status line under the brand adds detail on hover.

Visual tests

cargo test --test gui_visual -- --test-threads=1

Snapshots live in tests/snapshots/. Use a single test thread — wgpu snapshot rendering is not safe to parallelize. After intentional UI changes:

# Unix
UPDATE_SNAPSHOTS=1 cargo test --test gui_visual -- --test-threads=1

# PowerShell
$env:UPDATE_SNAPSHOTS="1"; cargo test --test gui_visual -- --test-threads=1

How it works

1. Probe the input with ffprobe (width, height, duration).
2. Resolve the target: landscape → 9:16, portrait → 16:9, unless --to is set.
3. Size a canvas whose long edge is --size and whose aspect is 9:16 or 16:9 (even pixels).
4. Filter
   • Blur: split the video, scale+crop a copy to fill the canvas, boxblur, scale the original to fit, overlay centered.
   • Color: scale to fit, pad with the chosen color.
5. Encode libx264 (veryfast or ultrafast), copy audio, -movflags +faststart.

--dry-run prints that ffmpeg command so you can paste, tweak, or learn from it.

vertify does not link against ffmpeg. It is a MIT-licensed Rust frontend. ffmpeg is a separate install with its own license (LGPL/GPL depending on the build).

Updating

CLI

vertify update           # check and install the latest release
vertify update --check   # check only, no download

vertify downloads the release archive for your platform, extracts the binary, and atomically replaces the running executable. After a successful update, restart the terminal session or run vertify --version to confirm.

GUI (Flip Stage)

The GUI checks for a new release in the background each time it starts. When a newer version is found, a narrow banner appears at the top of the window. Click it to download and install. Restart Vertify after the banner reports success.

Manual

Download the latest archive from the releases page, extract it, and replace your existing binaries.

Project layout

src/main.rs          CLI
src/bin/gui.rs       GUI entry
src/lib.rs           Probe, plan, ffmpeg command, convert()
src/gui/             Flip Stage (egui)
completions/         bash / zsh / fish
assets/fonts/        Syne + Source Sans 3 (OFL)

The CLI and GUI call the same convert() path. If you change encoding behavior, change it once in src/lib.rs.

Requirements

OS	Windows, macOS, Linux
Rust	1.80+ (to build from source)
ffmpeg	Bundled in official releases. Source builds need ffmpeg 4.x+ with libx264 on PATH (or VERTIFY_FFMPEG_DIR).

Hardware acceleration is not used. That keeps the filter graph portable. For huge batches, prefer --fast or a lower --size.

FAQ

Do I need to install ffmpeg? Not if you use the Windows installer or an official release zip/tarball. ffmpeg ships in the same folder. Source/cargo install builds still need ffmpeg on PATH.

Does it crop? No. The source is scaled with force_original_aspect_ratio=decrease and centered.

Can I keep 16:9 and just add blur on the sides of a portrait clip? Yes — that is the default when the input is taller than it is wide. Or pass --to 16:9.

Why is my file larger? You are re-encoding (and often adding pixels). Use a higher --crf (e.g. 23–26) or --fast if size matters more than quality.

Can I pass extra ffmpeg flags? Yes. Repeat --ffmpeg-arg for each extra token, for example: --ffmpeg-arg -pix_fmt --ffmpeg-arg yuv420p10le. You can still use --dry-run to inspect the final command.

Square video? Pass --to 9:16 or --to 16:9. Auto-detect refuses to guess.

Contributing

See CONTRIBUTING.md. Please read the Code of Conduct.

Bug reports and ideas: open an issue. Security: SECURITY.md.

License

MIT © Daylen Nguyen

Bundled GUI fonts (Syne, Source Sans 3) are SIL OFL 1.1 — see assets/fonts. Official releases bundle FFmpeg as a separate GPL program — see THIRD_PARTY.md.