Video Converter

Why MP4 is the format to land on

MP4 carrying H.264 video is the closest thing to a universal video format. It plays on phones, desktops, televisions, in every browser and in every editor, and hardware decoding for it exists on essentially everything.

Newer codecs compress better, and that matters when you are serving millions of views. For a clip you need someone else to be able to open, compatibility is worth more than the bytes.

What trimming does and does not re-encode

Video is stored as occasional complete keyframes with dependent frames between them, so a cut that does not land on a keyframe requires re-encoding the surrounding section to produce a valid file.

That is why a trimmed clip can be slightly softer than its source even though nothing else changed, and why trimming is slower than the file size suggests. Cutting from an original rather than from an already-trimmed export keeps the damage to one generation.

Speed changes and audio

Changing playback speed rewrites timing rather than pixels, so the video itself does not degrade. Audio is the awkward part: raising speed raises pitch unless the track is resampled, which is why a sped-up clip can sound comical.

For a silent demonstration this is moot and dropping the audio track entirely is usually the right call — it removes a surprising share of the file size and avoids autoplay restrictions on the web.

Working within a browser's limits

Everything here runs in the page, which means it runs in the tab's memory. Long or high-resolution sources are the practical ceiling.

• Short clips convert comfortably; a feature-length file is the wrong job for a browser tab.
• Keep the tab in the foreground — background tabs are throttled and the work stalls.
• Trim first, then convert, so the encode processes only the part you are keeping.
• Nothing is uploaded, which is also why your machine does all the work and can take a while.