WebM to MP4: help & limits

The local media engine downloads about 31 MB the first time you process a file. It runs in a worker, one file at a time. Processing is stopped after 15 minutes per file. Generated outputs are limited to 256 MiB; combined retained results are limited to 512 MiB. Phones may run out of memory even within these limits.

Container names do not guarantee codec support. Damaged, encrypted or unsupported streams fail with an error. Cancel stops the worker and retains completed outputs. Your originals are unchanged.

Creates a new encoded copy. Quality may change. Subtitles, extra tracks, chapters and source metadata are not copied. The original is unchanged.

Generated media is decoded again to check for errors. This does not guarantee visual or audio quality; preview the result before replacing an original. HDR, wide-gamut color and multiple-track preservation are not supported.

Files are read into browser memory. They are not uploaded or saved in browser storage. Reset releases previews; it does not securely erase RAM or downloaded files. Account traffic and website assets are separate from file processing.