Video Audio Merger

Combine a video and a separate audio file into an MP4. Keep the video encoding or convert for compatibility. Your files stay on your device.

01 · Video picture

02 · Audio soundtrack

Merge settings

Selected audio replaces the original soundtrack. Uses the first video picture and the first external audio track. Both tracks start together.

Video encoding

Copies the picture without re-encoding. Switch to compatibility mode if the codec cannot be muxed into MP4. Audio is converted to AAC.

Output duration

Stops when either the video or audio ends.

Output formatMP4 · Original video / AAC

Checks browser and engine capacity when processing starts. If it cannot be determined, actual reads and allocations decide what is supported.

No additional fixed file size cap. Inputs, output and engine use resources together; even smaller files can exhaust memory. Keep this page open while processing.

Local processing

Video and audio stay in your browser. The existing processing engine downloads on first use.

Keep the picture

Fast mode copies the video picture, ideal for separately downloaded video and audio. Compatibility mode handles codecs that cannot be muxed directly.

2 GiB is not a file capacity guarantee

The memory addressing ceiling depends on the current engine and browser. Files of that size are not guaranteed to work. Compress the video if memory runs out.

Adjust video volume Compress a video