Originally published at ffmpeg-micro.com

You need to join two or more video files into one. Maybe you're stitching together clips from a multi-camera shoot, assembling a highlight reel, or building an automated video pipeline. FFmpeg can do it, but the syntax trips up even experienced developers.

FFmpeg has three different ways to concatenate videos: the concat demuxer, the concat filter, and the concat protocol. Each one works differently, and picking the wrong one will give you corrupted output, missing audio, or a file that won't play. This guide covers all three methods, shows you when to use each, and includes working API examples so you can skip the CLI entirely.

The Concat Demuxer (Same Codec, Fastest Method)

The concat demuxer is the fastest way to merge videos because it doesn't re-encode. It copies the streams directly, which means zero quality loss and near-instant processing.…