Merged duration is shorter than the segments — normal?

Segments usually overlap by a second or two of buffering; small drift is fine. A big gap means missing or misordered segments.

There is an m3u8 file too — do I need it?

It is the playlist with the correct segment order; merge in list order when available. Otherwise sort by filename numbers.

Workflows 6 min read

Merge Cached Video Segments into One MP4

Browsers and downloaders split video into hundreds of small .ts segments. Merge them in order and the result is lossless — the segments came from the same source.

Step 1: order the segments

Segments are usually numbered (0.ts, 1.ts…). Filename order is playback order. A wrong order shows as jumps and broken sentences at seams — spot-check a few segments before merging.

Step 2: merge, then remux

Merged TS plays in most desktop players, but phones and social platforms want MP4. A remux changes only the container — byte-identical content, done in seconds.

Glitches at seams mean the segments are not from one source; that path needs re-encoding instead.

Step 3: verify

Check the start plays immediately, seams are smooth, and total duration equals the sum of segments.