Playback Proxies

Some video codecs can't be decoded by the player built into Clipthesis on every platform. When you open one of those clips, Clipthesis automatically generates a lightweight H.264 playback proxy — a preview copy that plays everywhere — and uses it inside the detail view. Your original file is never touched or re-encoded in place.

Which codecs need a proxy depends on the platform:

• macOS — HEVC (H.265), ProRes, and other Apple-ecosystem codecs play natively through the system decoders. Proxies are rarely needed.
• Windows — HEVC, ProRes, MPEG-2, and DNxHD have no built-in decoder, so Clipthesis creates a proxy for those clips.

If a clip's codec turns out to be unplayable even when it wasn't expected to be, Clipthesis falls back to generating a proxy on the spot the moment playback fails — you don't have to do anything.

What you'll see

The first time you open an affected clip, the detail view shows the clip's thumbnail with a "Preparing preview…" message and a live progress percentage while the proxy is encoded. When it finishes (usually well under a minute for typical clips), playback starts using the proxy. Every later open of the same clip plays instantly — the proxy is kept on disk and reused.

Scrubbing thumbnails in the library grid are unaffected: they're plain images and work for every codec without a proxy.

Proxy quality and size

Proxies are encoded with H.264 at a visually solid quality level (CRF 23) and capped at 1920 pixels wide — plenty for previewing and tagging. A proxy is typically much smaller than the original file. Audio is converted to AAC.

Proxies are previews, not deliverables. When you send clips to an editor (e.g. DaVinci Resolve) or copy them to a drive, Clipthesis always uses the original file.

Where proxies live

Proxies are stored in your app data folder alongside thumbnails, named by the clip's content hash:

• macOS: ~/Library/Application Support/Clipthesis/proxies/
• Windows: %APPDATA%\Clipthesis\proxies\

Because the filename is derived from the clip's content, a proxy survives drive letter changes, re-imports, and duplicate locations. When you delete a clip from your library (or remove its drive), its proxy is cleaned up automatically, and Clipthesis sweeps out any leftover proxies for deleted media on startup.

Pre-generating proxies in the background

By default, proxies are generated on demand — the first time you open a clip that needs one. If you regularly import footage in a codec your platform can't play (for example HEVC drone footage on Windows), you can have Clipthesis pre-generate proxies right after indexing so clips are instantly playable when you get to them.

This is controlled by the Pre-generate proxies after indexing toggle in Settings → Library (off by default). Generation runs one encode at a time in the background so it never starves imports or thumbnail generation of CPU.

Disk usage

Proxies accumulate in your app data folder — roughly a few hundred megabytes per hour of 1080p footage. If you need the space back, it's safe to delete files from the proxies/ folder while Clipthesis isn't running; any proxy that's needed again will simply be regenerated on next playback.