Alternatively, you can mux the audio and video together directly in FFmpeg to bypass Avidemux entirely:
The most reliable way to fix this is to transcode your audio into a format Avidemux natively supports as an external track. Use a tool like Audacity or FFmpeg to convert your file to one of the following: 16-bit or 24-bit PCM (Avoid 32-bit float). MP3: Standard constant or variable bitrate. avidemux cannot use that file as audio track
If you have a file that Avidemux won't take, you can use FFmpeg to "strip" the container and extract just the raw stream: Alternatively, you can mux the audio and video
Ensure you are using at least or the latest nightly build . Developers frequently release updates to handle tricky metadata in MP3 and AC3 files that previously caused this error. 4. Check File Metadata If you have a file that Avidemux won't
If you are trying to replace audio, make sure the new track is the same length as the video to avoid synchronization issues. Cannot use mp3 as audio track - avidemux.org
Avidemux generally requires raw audio streams for external tracks rather than audio already inside a container like .m4a or .mp4 .