Can Avidemux Add Chapters to MP4/MKV? (Workaround Included)

This page gives the honest answer first, then the exact workaround commands, so you can finish the job in under five minutes instead of hunting through menus for a feature that does not exist.

Why Avidemux has no chapter feature

Chapters are not part of the video or audio streams — they are metadata stored in the container (MP4 or MKV) that tells players “jump to 12:30 for the next section.” Avidemux’s job is stream-level work: cutting, appending, filtering, remuxing. Authoring container metadata like chapters, titles, or cover art is simply outside its scope, and no Avidemux version (including the current stable v2.8.1) adds it. Expecting it to appear in a menu is the trap; the workaround below is the intended path.

Workaround for MP4: add chapters with ffmpeg (no re-encoding)

ffmpeg can inject chapter metadata into an MP4 without touching the video or audio data at all — the job finishes in seconds. This uses generic ffmpeg syntax; flag behavior can vary slightly between ffmpeg versions, so check your build’s help if something looks off.

Step 1 — write a chapter file. Create a plain text file named chapters.txt in the FFmpeg metadata format. Times use TIMEBASE=1/1000, i.e. milliseconds. Here is an example with three chapters:

;FFMETADATA1
[CHAPTER]
TIMEBASE=1/1000
START=0
END=60000
title=Introduction
[CHAPTER]
TIMEBASE=1/1000
START=60000
END=180000
title=Main part
[CHAPTER]
TIMEBASE=1/1000
START=180000
END=300000
title=Conclusion

Adjust the START/END values to your video’s real section boundaries (60000 = 1 minute, 180000 = 3 minutes, 300000 = 5 minutes). Make the last chapter’s END reach at least the actual duration of the video.

Step 2 — mux the chapters in. Run:

ffmpeg -i edited.mp4 -i chapters.txt -map_metadata 1 -c copy output.mp4

What this does: -i edited.mp4 is your finished Avidemux export, -i chapters.txt is the chapter file, -map_metadata 1 takes the metadata (including chapters) from the second input, and -c copy copies all streams without re-encoding — zero quality loss, near-instant.

Workaround for MKV: MKVToolNix chapter editor

For MKV files, the friendliest tool is MKVToolNix GUI, which ships with a dedicated chapter editor:

1. Open your finished Avidemux export (the MKV) in the MKVToolNix chapter editor.
2. Add a chapter entry for each section and set its start time; give each a title.
3. Save. MKVToolNix writes the chapters into the file’s metadata without re-encoding anything.

Menu names and exact clicks can differ between MKVToolNix versions, so follow the labels in your installed version. (The ffmpeg method above works for MKV too, but the chapter editor is usually faster for hand-placed chapters.)

Verify the chapters landed

Open the final file in VLC and go to Playback → Chapter: your chapter titles should be listed, and selecting one should jump straight to that timestamp. If the menu is empty, double-check the millisecond values in chapters.txt (a chapter starting after the video’s real end is a classic mistake) and re-run the mux.

A common mistake to avoid

Do not treat the chaptered file as your new working copy. The moment you load output.mp4 back into Avidemux — for example to fix a cut — and save it again, the chapters are gone. The safe workflow is: edit in Avidemux → export master → add chapters → distribute. Need another edit later? Go back to the master, re-export, re-attach chapters. If you are new to Avidemux’s lossless workflow, start with cutting without re-encoding; for a broader tool comparison see Avidemux vs ffmpeg.