A local Linux video compressor with one promise: the output is never larger than the size you set. Pick a video, a maximum size, and a codec. ExactSize works out the bitrate, encodes, measures the real file, and only saves it once it fits.
chmod +x ExactSize-1.8.29-x86_64.AppImage
./ExactSize-1.8.29-x86_64.AppImageFFmpeg is bundled. On first run the AppImage adds itself to your app menu with its icon.
- Strict size ceiling: packet-aware container overhead is budgeted up front, then encodes are measured stream by stream and auto-corrected in strict bitrate cycles at maximum FPS → midpoint FPS → minimum FPS → lower resolution order; an oversized attempt never replaces your output.
- GPU encoding: NVENC, Quick Sync, VAAPI, and AMF. Every encoder is test-run at launch, so only ones that actually work on your machine are offered, and they're preferred by default.
- Modern codecs: H.264, H.265, H.266/VVC, AV1, VP9. AV2 is wired up and unlocks itself the moment FFmpeg ships an encoder.
- Quick presets: one-click size targets (10–200 MB), speed/quality tiers from Fastest to Higher quality, a dual-handle 5 fps-to-source adaptive frame-rate range that tests at most maximum/midpoint/minimum and restarts bitrate correction at every tier, and an independent Automatic resolution toggle that downscales from the selected starting resolution only after all bitrate and FPS options are exhausted.
- Visual comparison: after a successful compression, open a large before/after viewer, drag the divider, hover over the timeline for a lightweight compressed-frame thumbnail, or click and drag to inspect both encodes in the main view—all without browser codec limits, preview encodes, or temporary files.
- Single instance: launching ExactSize while it is already open shows a native warning and exits the new process without spawning another app window or leaving a lock file behind.
- Remux / Mux: switch containers losslessly without re-encoding; if only the audio doesn't fit the new container, Mux copies the video untouched and converts just the audio.
- Drag & drop that behaves: dropped files keep their real location, so outputs land next to the source, not in /tmp.
- At home on KDE: frameless window with native drag, resize, and rounded corners.
- Private by design: no telemetry, no accounts, no network uploads. Everything stays on 127.0.0.1.
| Container | Video | Audio |
|---|---|---|
| MP4 | H.264, H.265, H.266, AV1 | AAC, MP3 |
| MKV | H.264, H.265, H.266, AV1, AV2*, VP9 | AAC, Opus, Vorbis, MP3 |
| WebM | AV1, VP9 | Opus, Vorbis |
| MOV | H.264, H.265, AV1 | AAC, MP3 |
Audio can also be dropped entirely. AV2 stays greyed out until FFmpeg ships an encoder.
Most distros strip patented codecs from their stock GPU drivers. Install the full driver and relaunch; encoders are re-detected every start.
| GPU | Distro | Install |
|---|---|---|
| AMD | Fedora | sudo dnf install mesa-va-drivers-freeworld (RPM Fusion) |
| AMD | openSUSE | opi codecs (Packman) |
| AMD | Ubuntu / Debian / Arch | nothing to install |
| Intel | Fedora | sudo dnf install intel-media-driver libvpl intel-vpl-gpu-rt (RPM Fusion) |
| Intel | Ubuntu / Debian | sudo apt install intel-media-va-driver-non-free libvpl2 libmfx-gen1.2 |
| Intel | Arch | sudo pacman -S intel-media-driver vpl-gpu-rt |
| NVIDIA | Fedora | sudo dnf install akmod-nvidia xorg-x11-drv-nvidia-cuda-libs (RPM Fusion) |
| NVIDIA | Ubuntu | sudo ubuntu-drivers install |
| NVIDIA | Debian / Arch | sudo apt install nvidia-driver / sudo pacman -S nvidia |
Hardware limits no driver fixes: AV1 encoding needs RX 7000+ / RTX 40+ / Intel Arc; VP9 encoding is Intel-only; no GPU encodes H.266 yet.
Needs Go 1.24+, curl, and tar with xz support. Everything else (static FFmpeg, appimagetool) is downloaded and checksum-verified automatically:
./scripts/build-appimage.shThe result lands in build/ExactSize-<version>-x86_64.AppImage. Run the tests with go test ./....
MIT. FFmpeg is bundled under its own license, see THIRD_PARTY_NOTICES.md.