Merge audio with video voiceover, dubbing & BGM
Replace the original soundtrack or mix a new track on top—ideal for MP4 dubs, narration, and light background music. Export MP4, MKV, or WebM. Merging runs locally in the SnapVee desktop app: nothing is uploaded and there is no size ceiling.
Runs in the SnapVee desktop app
Processing happens on your own machine — files are never uploaded.
- No upload, no queue
- No file size ceiling
- Batch a whole folder at once
How merging works
Add your video
Bring MP4, MOV, WEBM, AVI, MKV, or other supported cuts from your device.
Add your audio
Add MP3, WAV, AAC, M4A, FLAC, or OGG—the track you want merged in.
Choose mode & format
Pick replace or mix, then MP4, MKV, or WebM before you queue the job.
Save the merged file
Write the finished render next to the original, or to any folder you choose.
Why teams use this merge flow
Replace or mix in one panel
No separate DAW session required for simple swaps—switch modes without leaving the browser workflow.
Task history stays visible
Processing, failures, and completed renders stay in one list so nothing disappears behind a spinner.
Built for quick handoffs
Perfect for social cuts, course modules, and client reviews that need a new VO layer fast.
Why merge inside SnapVee?
Compared with a random online mux page, the difference is whether your file leaves the machine.
Replace/mix modes and MP4/MKV/WebM outputs in one place.
Runs locally — nothing is uploaded and nothing is stored on a server.
No hard size cap, and the result is written straight to your disk.
Your file is uploaded to someone else's server before anything happens.
Free tiers cap size, and large videos time out mid-upload.
Results sit behind a retention window and a shared queue.
Merge video and audio — FAQ
Long-tail answers for replacing a track, mixing voiceover, and export formats.
How do I add voiceover or dubbing audio to an MP4?
Add your video and a separate audio file in the SnapVee desktop app, choose Replace to swap the original track or Mix to blend with it, then pick MP4, MKV, or WebM and save. Everything runs on your own machine.
What is the difference between replace and mix audio mode?
Replace removes the video’s original audio and uses your new file as the only soundtrack. Mix keeps the original audio and layers your file on top—useful for light background music when levels are balanced.
Can I merge audio with video and export MKV or WebM?
Yes. After both files are selected you can choose MP4, MKV, or WebM as the container before starting the merge task.
Do I need an account to merge video and audio?
Yes. Merge runs after you sign in so tasks can be tracked and results delivered securely.
How long are merged files available to download?
The merged file is written straight to the folder you choose. Nothing goes through the cloud, so there is no retention window.
How do I add background music to a video?
Add the video and the music file together, choose Mix so the original audio is kept and the music is layered on top, then export MP4, MKV, or WebM. Pick Replace instead if the music should be the only soundtrack.
Does merging re-encode and degrade the video?
No. The video stream is copied through untouched (-c:v copy) and only the audio is encoded, so picture quality is identical to the source and the merge finishes fast.
What happens if the audio is longer than the video?
In Replace mode the output ends when the shorter of the two streams ends, so the extra audio is cut off. Trim the audio to the video length first if you need the whole track.
Every SnapVee tool in one place
Ready to lay in new audio?
Install the SnapVee desktop app, add your video and audio, pick replace or mix, then save the merged file. Everything runs on your own machine.