Avidemux No Sound? Fix Playback and Export Audio Problems

No sound in Avidemux has two completely different causes: silent preview and silent exported files. Silent preview is an audio playback device problem — Avidemux ships with a null “DUMMY” device selected, so the preview plays mute until you pick a real output. Silent exported files are an audio encoding/index problem — a codec/container mismatch, an Audio Output of “None”, or a corrupt index file. Identify which one you have first, because the fixes are different.

Case 1: No sound during preview (video plays mute inside Avidemux)

This is the most common complaint. Avidemux defaults the preview audio device to DUMMY, a null device that produces no sound at all. Fix it in one step:

  1. Open Edit → Preferences, then switch to the Audio section.
  2. Change the audio device away from DUMMY to a real output for your operating system:
    • Windows: the WIN32 option.
    • Linux: PulseAudio or ALSA.
    • macOS: the corresponding output option for your build.
    (The exact labels and menu layout can vary between builds and platforms, so check your build’s Preferences dialog if they look different.)
  3. Confirm and restart playback — sound should play while scrubbing or playing the timeline.

Also check: make sure your system volume and the player volume are up, and that the source file itself actually contains an audio track (Audio → Select Track will show whether a track is detected).

Case 2: No sound in the exported file (preview is fine, output is silent)

If you hear sound inside Avidemux but the saved file is mute, the problem is in the export settings or the file index. Work through these in order:

1. Check Audio Output is not “None”

In the left panel, the Audio Output dropdown must be set to a real encoder (e.g. AAC (lav) for MP4, or Copy if the source audio is already compatible). If it says None, Avidemux drops the audio stream entirely — preview still sounds fine, but the exported file has no audio at all.

2. Match the audio codec to the container

Not every audio codec works in every container. AC3 in MP4, for example, can produce silent or unplayable files on some players. For MP4 output, AAC is the safe default; for MKV you have more freedom (AAC, AC3, MP3, Vorbis). When in doubt, use AAC (lav) with an MP4 muxer.

3. Rebuild a broken index

A damaged or stale index can corrupt the audio stream in the export. Close the file in Avidemux, find the index file sitting next to the video (same name with a .idx2 extension), delete it, and re-open the video so Avidemux rebuilds the index from scratch. Then re-save the file.

4. Confirm the player is not the problem

Some players (notably browser-based players and certain hardware decoders) choke on specific codecs like E-AC3 or DTS. Play the exported file in VLC or MPV before concluding Avidemux produced a silent file.

Diagnostic shortcut: if the exported file is silent in every player and Avidemux’s Audio Output was set to None, just re-save with an encoder selected — the original source file was never touched, so nothing is lost.

Frequently asked questions

Why is there no sound when I play a video in Avidemux?

Because the preview audio device is set to DUMMY, a null device that produces no sound. Go to Edit → Preferences → Audio and select a real output device for your OS (WIN32 on Windows, PulseAudio or ALSA on Linux).

My exported video has no sound but the preview is fine. What went wrong?

The most common causes are Audio Output set to None (the audio stream is dropped), an audio codec/container mismatch, or a corrupt .idx2 index. Set Audio Output to an encoder such as AAC (lav), match the codec to the container, or delete the .idx2 file and rebuild the index.

Should I use Copy or AAC for Audio Output?

Use Copy if the source audio already plays fine everywhere and you want zero quality loss. Use AAC (lav) if you are re-encoding anyway, if the source codec is unusual, or if some players are silent on the export.

The exported file is silent in my browser but plays fine in VLC. Why?

Browsers and hardware players support fewer audio codecs than VLC. Your file likely uses a codec the player can’t decode (e.g. E-AC3 or DTS). Re-export with AAC audio for maximum compatibility.