A local Linux, Windows, and Android 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-1.12.4-x86_64.AppImage
./ExactSize-1.12.4-x86_64.AppImageFFmpeg is bundled. On first run the AppImage adds itself to your app menu with its icon.
Extract ExactSize-1.12.4-windows-x86_64.zip and run ExactSize.exe. Keep ffmpeg.exe and ffprobe.exe beside it; the folder is portable and needs no installer. ExactSize uses Edge, Chrome, Brave, or the registered browser for its local interface.
Install ExactSize-1.12.4-android-arm64.apk on a 64-bit Android 9 or newer device. The APK uses the Android document picker for input and output, bundles software x264/AAC plus dav1d for reliable AV1 input decoding, and runtime-probes FFmpeg's native Android MediaCodec encoders. H.264, H.265/HEVC, VP9, and AV1 are exposed when the device can encode them; AV1's usable frame-size limit is also probed so oversized phone videos are fitted to the encoder instead of failing. Scaling follows the input's display rotation and pixel aspect ratio, so portrait, square, 4:3, ultrawide, and anamorphic sources retain their original shape. Compression continues through an Android foreground media-processing service when the app is sent Home or dismissed from Recents; its notification shows the real phase, percentage, time remaining, and encoded size, provides a Cancel action, and alerts separately on completion or failure. H.264/HEVC/VP9 are commonly hardware-backed, while AV1 may be a software device fallback (the Pixel 7 Pro test device reports that behavior). Desktop-only encoding libraries such as x265, libaom, libvpx, and vvenc are not bundled in the APK yet because they substantially increase size and CPU/battery cost. The first local build creates a development signing key under build/android/keys; set the documented signing environment variables in scripts/build-android.sh when using your own release key.
- Strict size ceiling: packet-aware container overhead is budgeted up front, then encodes are projected and auto-corrected in strict bitrate cycles at maximum FPS → midpoint FPS → minimum FPS → lower resolution order. Low-bitrate GPU attempts are assessed after at most 30 encoded seconds or about one minute of wall time, with a confidence band that accounts for heavier opening scenes; an attempt is stopped and cleaned up once the evidence shows it cannot fit, and 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, codec-aware per-track audio bitrate and dual-handle 5 fps-to-source adaptive frame-rate sliders, and an independent Automatic resolution toggle that downscales from the selected starting resolution only after all bitrate and FPS options are exhausted.
- Update checks: once the app is ready, it checks the latest published GitHub Release and shows a compact header action only when a newer version is available.
- 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 — checked against your recent-documents history first, then a fast, bounded scan of likely folders and external drives — 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, and no video uploads. The only outbound request is one public GitHub Release check at startup; all video processing stays local.
| 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.
All targets need Go 1.24+ and curl. Platform toolchains and media payloads are downloaded into build/ and verified by their build scripts.
Linux AppImage (tar with xz support is also required):
./scripts/build-appimage.shThe Linux build embeds GitHub zsync update metadata and produces:
build/ExactSize-<version>-x86_64.AppImagebuild/ExactSize-<version>-x86_64.AppImage.zsync
Windows portable ZIP (unzip and zip are also required):
./scripts/build-windows.shThis produces build/ExactSize-<version>-windows-x86_64.zip with ExactSize.exe, ffmpeg.exe, ffprobe.exe, licenses, and notices.
Android arm64 APK (make, tar, unzip, and zip are also required):
./scripts/build-android.shThe Android script downloads a pinned JDK, Android SDK/NDK, FFmpeg, x264, dav1d, Meson, and Ninja, builds the native payloads from source, and produces build/ExactSize-<version>-android-arm64.apk.
Run the Go tests for the shared application code with:
go test ./...Upload the platform artifacts to the matching GitHub Release.
For a tagged Linux release, the release helper refuses to publish unless both AppImage files exist, uploads them together, and verifies both asset names afterward:
./scripts/publish-release.shMIT. FFmpeg is bundled under its own license, see THIRD_PARTY_NOTICES.md.