Avidemux Filters Greyed Out? Why It Happens and How to Fix It

Avidemux filters are greyed out because Video Output is set to Copy. Filters can only transform video pixels when the video is being re-encoded; in Copy mode the stream passes through untouched, so Avidemux deliberately disables every filter. This is by design, not a bug. The 30-second fix: change Video Output from Copy to an encoder such as x264, and the Filters button under the Video menu becomes clickable immediately.

Why the filter button remains greyed out

Nearly every “the filter button remains greyed out” report has the same cause: Copy mode. Copy means “keep the original compressed frames exactly as they are.” Applying a filter — resize, crop, sharpen, burn-in subtitles — requires decoding each frame, modifying it, and encoding it again. That second pass is what an encoder does, and what Copy mode explicitly skips. So Avidemux greys out the Filters option to stop you from applying an impossible combination. You will also notice the Output Format options behave the same way: encoding-related controls unlock only once a real encoder is selected.

Quick test: open a video, look at the left-side Video Output dropdown. If it says Copy, you have found the reason. Switch it to Mpeg4 AVC (x264) and check the Video → Filters menu again — it should now be fully active.

The 30-second fix

  1. Open your video in Avidemux.
  2. In the left panel, change Video Output from Copy to an encoder such as Mpeg4 AVC (x264) (or Mpeg4 ASP (xvid4) for older devices).
  3. Open Video → Filters — the filter list is now available. Add your filters (crop, resize, subtitle burn-in, etc.).
  4. Set Output Format (usually MP4 Muxer or MKV Muxer) and save the file. Your filtered output is re-encoded.

Note: because filters force re-encoding, the export takes longer than a Copy-mode save and quality depends on the encoder settings. That trade-off is unavoidable — there is no way to apply filters in Copy mode.

Two less common reasons filters stay greyed out

1. No video is loaded

The Filters menu is disabled when no file is open. This also happens if Avidemux failed to index the file (a corrupt or incomplete index leaves the timeline empty). Close the file, delete any leftover index file with the same name plus a .idx2 extension, and re-open the video so indexing runs again.

2. Build or configuration issue

If Video Output is already set to an encoder but Filters still won’t open, a stale configuration can be the culprit — especially if you upgraded from an old build or run a nightly. Try resetting Avidemux’s configuration and restarting the program; exact menu paths vary between builds, so check your build’s preferences location if you can’t find it. Also make sure you are running the official stable release 2.8.1 rather than an experimental development build, where menu behaviour can be unstable.

Frequently asked questions

Why are my filters greyed out in Avidemux?

Because Video Output is set to Copy. Filters require re-encoding, and Copy mode passes the stream through untouched. Switch Video Output to an encoder such as x264 and the Filters menu unlocks.

Do I have to re-encode my video to use filters?

Yes. Every filter modifies actual video frames, so the output must be re-encoded. Only operations that never touch the pixels (cutting, copying streams into a new container) work in Copy mode.

I switched to x264 but the filters are still greyed out. Why?

Check that a video is actually loaded and indexed first. If it is, try resetting Avidemux’s configuration and restarting, and confirm you are on stable release 2.8.1 rather than a nightly build.

Can I add subtitles without re-encoding?

Burning subtitles into the picture is a filter and requires re-encoding. If you want to avoid re-encoding entirely, mux the subtitles as a separate selectable subtitle track into an MKV container with a tool like MKVToolNix instead — no re-encoding, no quality loss.