Merge Audio & Video
Audio + Video → MP4 · Muxed on our servers, no quality loss
Put a video file and an audio file together and get one complete MP4. The video stream is copied rather than re-encoded, so there is no quality loss. Processing happens on our servers, so even a phone can upload large files — and your originals are deleted the moment the merge succeeds.
- Merged on the server — the video is never re-encoded
- Your uploaded originals are deleted once the merge finishes
- No sign-up — open the page and go
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Step 1: Pick the video
Choose the video file to work with on the left.
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Step 2: Pick the audio
Choose the audio track to merge in, in the middle.
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Step 3: Upload and merge
Hit “Start merge”. Both files upload, the server builds the MP4, and you can download it a moment later.
Add audio to a video
Add Audio To Video · the picture is kept exactly as it is, only the audio track is replaced
The merged video will preview here
[info] Server-side merge · the video and audio are uploaded, and the originals are deleted as soon as the merge finishes
[info] The result is cleaned up automatically — download it in time
Merging runs on our servers: the video and audio are uploaded first, the originals are deleted as soon as the merge succeeds, and the result is cleaned up automatically once its retention period ends. The per-file limit is set by the server — please bear with large files.
FAQ
Merge Audio & Video FAQ
- Do I have to upload my files?
- Yes. The video and audio are uploaded to our servers, where FFmpeg remuxes them into a single MP4 (the video stream is copied, not re-encoded). Your originals are deleted immediately after a successful merge.
- Is the video's original audio kept?
- No. The audio track is replaced by the file you choose. The picture is left untouched and is not re-encoded, so there is no loss of visual quality.
- Which formats are supported?
- Video: MP4, M4V, MKV, MOV, WEBM, FLV, AVI, TS, MPG/MPEG, WMV and 3GP. Audio: MP3, M4A, AAC, WAV, FLAC, OPUS, OGG/OGA, WMA and AIFF. Anything outside that list is rejected before the upload starts, so you never waste bandwidth on a large file.
- Does merging use up my download quota?
- Yes. The server has to read the whole video and write it back out, which costs about the same as a regular download, so each merge takes 1 from your daily allowance. It shares that allowance with link downloads, and signing in raises the limit.
- How long are files kept?
- Uploaded originals are deleted as soon as the merge succeeds. If you never start the merge, they are cleaned up when the staging period expires (120 minutes by default). Results are kept by tier: 30 minutes when signed out, 24 hours when signed in — download them in time.
- Why is a large file slow to process?
- The wait has two parts: upload speed depends on your connection, merge speed on the server and the file's duration. The merge itself is a remux rather than a transcode, so it is usually much faster than re-encoding.
- Can I use it on a phone?
- Yes. The merge runs on the server, so your phone only handles the upload and download. Wi-Fi is recommended — and for very large files, compressing first can help.