4 articles about video-composition.
H.264 has no alpha channel, so ffmpeg overlay transparent video jobs render black boxes. Fix it with VP9 WebM, ProRes 4444, alphamerge, and one API call.
The ffmpeg side by side recipe that actually works: hstack needs matching heights, vstack matching widths, and shortest=1 stops the short clip freezing.
Crossfade clips with ffmpeg xfade: transition types, the offset math people get wrong, carrying audio with acrossfade, and chaining more than two clips.
Concatenate clips programmatically with a composition API: why FFmpeg's concat demuxer breaks on mixed inputs, the real CLI commands, and the one-call fix.