Compressed, low-resolution copy of original footage — enables smooth editing on weak hardware. Final decisions on full-resolution; proxies just for workflow efficiency.
You need proxies when your editing system starts to lag — and that happens faster than you think. Modern cameras deliver footage in resolutions and data rates that can bring a standard iMac or even some Windows workstations to a crawl. Instead of editing with full RAW or ProRes 422 HQ — which is almost impossibly smooth at 4K or 6K — you create compressed working copies: usually ProRes 422 Proxy or DNxHD LB (Low Bitrate). These are typically 25–50% of the original resolution, with a greatly reduced data rate, but pixel-perfect aligned with your original timecode.
The practical workflow: You generate proxies during camera data backup or afterward — depending on the project scope, this can take an hour, but it saves you days of leisurely work during editing. The NLE (Your editing system — be it Premiere, Final Cut, or Avid) works with the proxies, but writes all edit decisions offline. At the end, before the final export, you relink to the original footage — and the engine re-renders all cuts, color corrections, and effects in full resolution. Your editing momentum remains unchanged, but your computer has breathed during the process.
Practical limitations: Not every situation allows for proxies. For ultra-low-budget or documentary work, where you need to perform quickly, the render overhead isn't worth it. For VFX-heavy material, you often need proxies anyway, because the compositor also works on proxy resolution until the final render. Color grading is ideally moved to the finish — with proxies, color calibration becomes difficult, as compression washes out color depth. Some editors work hybrid: rough cut on proxy, director's review on original, final conform back to proxy, then back to original — depending on project complexity.
The proxy strategy is also a backup strategy: your original media pool remains untouched, you work in a separate instance. If something goes wrong — hard drive errors, accidental effect calculations — your editing decisions are cleanly separated. This is a classic post-professionalism pattern: work quality from the start, risk mitigation through structure.