How this tool works
Three optional pieces around your main video: a still image held at the very start, a clip before it, and a clip at the end or dropped in at a moment you choose. Everything is matched to the main video, so clips of different sizes and shapes can be used without preparing them first. The running order is shown, with what will happen to each piece, before anything is encoded.
The thumbnail is a real part of the video rather than a poster frame stored in the file. Poster support is inconsistent across players, and the platforms people usually mean — YouTube, Instagram — take their thumbnail at upload and ignore whatever the file carries. A couple of seconds of the image at the front works everywhere, which is what is actually wanted even when it is called a thumbnail. Placing the outro at a moment rather than the end splits the main video around it, so the video resumes afterwards.
How mismatched pieces are handled
- Nothing is refused for being the wrong size: an intro at 4K and a video at 1080p can be joined. Everything is re-encoded to the main video, and the list says which pieces will be changed and how before you commit to the wait.
- A different shape is fitted, not stretched: blurred fill scales the piece to fit and puts a blurred copy of it behind, so nothing is cropped and nothing is black. That matters most for an intro, which is usually a logo — filling and cropping would cut its edges off.
- Silence is generated where a piece has none: a still image and a silent intro both need their place in the audio track. Without it the sound ends early and everything after it plays out of step with the picture.
- Everything is re-encoded, including your main video: joining means writing one new file, so the main video is decoded and encoded again along with the rest. That costs a little quality, which is unavoidable in any browser.