Merge Videos

What Merge Videos helps you do

Join several clips into one file without uploading them. When the clips share a codec, profile and resolution, the tool copies the encoded packets and the merge is fast and lossless. When they differ, normalization re-encodes every clip to a common format before joining, so a mixed set still produces a single playable file.

Clips are read, combined and written in your browser. No file is uploaded, and no merged copy is stored on a server.

How it works

A packet copy writes the existing encoded frames one after another into a new container, which is why compatibility matters: the decoder must accept the same format for the whole timeline. Normalize mode decodes each clip, scales it to the first clip's resolution and re-encodes to H.264/AAC before writing the combined file. The clip order in the list becomes the playback order, and the total duration is the sum of the parts.

How to use Merge Videos

1. Add the clips you want to join and arrange them in order.
2. Check whether all clips share a codec, profile and resolution.
3. Leave packet copy enabled for compatible clips, or enable normalization.
4. Pick the output container.
5. Start the merge and wait for the progress indicator.
6. Play the result through the joins to confirm the order and the audio.

When to use it

• Combine several parts of a meeting or lecture into one recording.
• Join takes from the same camera without losing quality.
• Assemble a sequence of short clips for a review.
• Stitch exported segments back into a single file.
• Put an intro and an outro around an existing clip.

When not to use it

• Do not merge clips with different resolutions in packet-copy mode.
• Do not expect a smooth transition; this is a hard cut between files.
• Avoid normalization unless the clips are incompatible, because it re-encodes everything.

Example

Four screen recordings from the same tool, all H.264 at 1920×1080, are merged in packet-copy mode in a few seconds. A fifth clip recorded at 1280×720 forces normalization, which re-encodes all five to the first clip's resolution so the result plays without a mid-file resolution change.

What you can do with Merge Videos

• Add and reorder multiple clips.
• Copy packets when the formats match.
• Normalize incompatible clips to a common format.
• Keep audio from the clips that have it.
• Export MP4 or WebM.
• See the combined duration before exporting.
• Run the merge locally with no upload.
• Merge more than two clips in one pass.

Example workflow

Convert first when the clips come from different devices. Saving every part as MP4 with the same codec and resolution makes the merge lossless and much faster than normalization.

Trim each part before merging. Removing false starts and dead air at the clip level produces a tighter final file and avoids a second pass over the result.

Check the audio at every join before publishing. A clip recorded with a different microphone can change the level abruptly, and a hard cut makes that obvious to the viewer.

What to know before you start

• Packet copy requires matching codecs, profiles and resolutions.
• Normalization re-encodes and introduces a small quality loss.
• A clip without audio is allowed, but the result keeps audio only from the clips that have it.
• There are no crossfades or transitions.
• The result is assembled in memory, which limits very large sets.

Common mistakes

• Merging portrait and landscape clips without normalizing.
• Assuming packet copy will work across different cameras.
• Leaving a clip out of order and discovering it after the export.
• Merging first and trimming later, which re-encodes more footage than necessary.
• Joining clips with different frame rates and expecting packet-copy speed.
• Assuming the output is re-encoded when packet copy is used.

Troubleshooting

If the merge fails, at least one clip probably differs in codec, profile or resolution. Enable normalization or convert the odd clips first.

If the audio cuts out at a join, that clip may have no audio track. Add a silent track or accept the gap.

If the result is much larger than expected, normalization re-encoded every clip. Convert to matching formats and use packet copy instead.

If the order is wrong after exporting, the list order was different when the merge ran. Reorder the clips and run it again; the encode itself does not shuffle them.

If the audio level jumps at a join, normalize the clips in an editor or accept the change; the merge does not adjust levels.

Related standards and documentation

• ISO/IEC 14496-12 describes the MP4 container written by the muxer.
• H.264/AVC and AAC are the common normalized output pair.