How It Works and Privacy

How It Works & Privacy

For the curious: how Tamp hits a size target reliably, how it picks an encoder, and exactly what does (and doesn't) leave your machine.

How compression works

Tamp bundles a static FFmpeg and drives it from a Rust engine. The flow for a single conversion:

1. Plan the bitrate from the target. Roughly: video bitrate = (target size − audio budget) ÷ duration, minus a ~5% container margin. Audio is encoded at a modest fixed rate (or dropped if you chose Strip audio), and +faststart is set so the file plays instantly when streamed.
2. Cap quality only as needed. If the target would starve the bitrate (think a 4K screen recording into 10 MB), Tamp automatically caps the frame rate and steps the resolution down just enough to keep the result legible — on top of any caps you set in the preset.
3. Encode. With enough bitrate headroom, the OS hardware encoder hits the size quickly. When a target is tight enough that quality matters, Tamp uses precise two-pass software encoding instead.
4. Verify and converge. Tamp checks the result; if it ever overshoots, it re-encodes with a corrected bitrate. It never delivers a file over your target — and if a target is genuinely unreachable, it tells you (see "Target too small") rather than handing you unwatchable output.

Hardware vs. software encoding

The Use GPU encoder setting (on by default) uses your platform's hardware encoder — VideoToolbox on macOS; NVENC / QSV / AMF / Media Foundation on Windows, whichever your machine has. It's fast and great for most targets. For very tight targets where precision wins, Tamp switches to two-pass software (x264). Turn the setting off to always prefer software.

Choosing a format

Format	Codec	Best for
MP4	H.264 + AAC	The safe default — plays everywhere, hardware-accelerated.
WebM	VP9 (two-pass) + Opus	The web; often smaller than MP4 at the same quality.
GIF	palette-optimized, size-targeted	The handful of places that still demand a GIF (no audio).

Splitting

When one clip can't look good under your target, Tamp can compress it as several parts that each fit the full target — automatically (smart) or on your terms (static). See Presets & Splitting.

Privacy & your data

Tamp is local-first by design:

• Everything runs on your machine. Encoding uses the bundled FFmpeg; your videos are never uploaded anywhere.
• No telemetry, no analytics, no account. Tamp doesn't phone home.
• One optional outbound request: if you turn on Check for updates automatically, Tamp asks the GitHub releases API whether a newer version exists. That request carries nothing about you or your files — just a standard request for the public release list. It's off by default; see Updates.

Logs

Tamp keeps rotating local logs (capped at roughly 10 MB total) recording the FFmpeg command lines and any errors — invaluable when something fails. They stay on your machine. Open the folder from the tray menu → Open Logs, and find the app version at the bottom of Preferences. When reporting a bug, attaching the relevant log lines helps a lot — see Troubleshooting.

Updates

The opt-in update check (above) surfaces a small notice when a newer release exists, with Download (opens the GitHub release page) and Later (dismisses it — Tamp won't nag again for that same version). You install the new build yourself, the same way as the first time — see Installing Tamp.