Add audio to video
Mix or replace a video's soundtrack with an audio file.
Drop a video here or choose from your device
MP4, MOV, WebM, MKV, AVI, or M4V. Processing stays on this device.
A practical guide to Add audio to video
Add Audio to Video mixes a new audio file with a video's soundtrack or replaces the existing track. The workflow uses fixed mix levels and ends the export with the shorter applicable stream.
Example: add narration to a silent product clip
Align the narration with the opening frame, replace silence rather than mixing it, and watch the full export for timing drift.
Task-specific steps
- 1
Add the video and audio, then compare their durations and make sure both should begin together at the opening frame.
- 2
Choose Replace original audio to discard the video's soundtrack, or leave it off to combine both tracks at fixed levels.
- 3
Render the video, watch it from start to finish with sound, and verify the fixed mix remains intelligible.
Options that affect the result
- Replace original audio maps only the added track into the result.
- Mix mode combines the original and added tracks at fixed levels; there are no per-track volume controls.
Limitations to know first
- The tool does not provide delay, level, or time-stretch controls and cannot synchronize speech to lip movement automatically.
- Mixing two loud sources at fixed levels can clip or mask dialogue, so adjust the source files before adding them when needed.
Questions specific to this task
What happens if the audio is shorter than the video?
The export uses shortest-stream behavior, so it can end when the applicable audio stream ends. Match durations before export when the full video must remain.
Can I delay the new audio track?
No built-in delay control is available. Add leading silence to the source audio before using this tool when a later start is required.