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AREM Labs

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Video Merger

Combine multiple video clips into a single file in your browser. Reorder tracks, match frame rates automatically, and merge footage without server uploads.

1Drop your videos here

MP4, WebM, MOV, MKV, AVI, FLV, 3GP · joined in order · up to 1 GB

Tips

  • The 30 MB video engine downloads once on first use and remains cached for offline stitching.
  • Drag and drop clips in the list to adjust the playback sequence before merging.
  • Matching codecs and resolutions combine significantly faster without full re-encoding.

How to use it

  1. 1 Select or drop multiple video clips into the merge queue.
  2. 2 Drag items within the list to arrange your desired playback order.
  3. 3 Click the merge button to concatenate and standardize your clips into a single video.
  4. 4 Save the finalized output file directly to your device storage.

What you should know

Combining separate video recordings into a continuous sequence is essential for assembling multi-take footage, presentation slides, or social media reels. Video files often differ in resolution, aspect ratio, frame rate, and audio sample rates, which prevents direct container concatenation. When stream parameters mismatch, the encoding pipeline must normalize the clips by scaling frames to a uniform pixel grid, conforming timebases, and re-encoding video streams using standard H.264 or H.265 compression algorithms. Matching properties beforehand allows stream-copy merging without generational loss, while mixed inputs require re-encoding that balances bitrate and structural quality across cuts.

This tool merges multiple video clips directly in your browser tab using client-side WebAssembly execution without uploading footage to external servers. You can reorder uploaded clips to dictate playback sequence, and the engine automatically standardizes differing resolutions and frame rates into a cohesive output stream. Because the WebAssembly engine runs on a single CPU thread, processing high-bitrate or high-resolution files takes time proportional to total duration. Non-standard container metadata, subtitle tracks, and extra audio streams might be stripped during standardization to ensure broad cross-platform playback compatibility in modern browsers.

Frequently asked questions

Why does merging mixed video formats take longer?

When clips have different resolutions, codecs, or frame rates, the engine must decode and re-encode every frame to normalize the output stream. Clips with identical encoding parameters merge much faster through direct stream copying.

Are my uploaded video files stored on a server?

No, all processing occurs locally inside your browser via WebAssembly, so your video data never leaves your computer or mobile device.

What happens if my clips have different audio sample rates?

The engine resamples and resynchronizes all audio tracks to a standard stereo configuration, ensuring seamless transitions without pitch shifts or audio dropouts between clips.

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