Rewrap or Re-encode? What Turning a 130 MB .MOV and a 113 MB .WebM Into MP4 Actually Does
"Convert it to MP4" sounds like one job. It's really two different jobs that happen to produce a file with the same extension: Rewrap : move the same video and audio packets into an MP4 container. It takes seconds, the size stays the same and the picture can't get worse, because nothing is decoded. Re-encode : decode the video and compress it again as H.264. It takes longer and costs some quality, but it's the only route that makes the file smaller or changes what's inside. Which one you need depends on two questions: what codec is inside your .mov or .webm, and does the place you're sending it care about the extension, the codec or the megabytes? I ran both routes on two real files: a 130 MB iPhone-style .MOV and a 113 MB screen recording saved as .WebM. Everything ran in Chrome on videocompress.dev , a browser video tool I build (so read this with that in mind). Nothing was uploaded, and I checked every output with ffprobe . The short answer (measured) ...