Convert MP4 video to MKV in a browser-only batch. Files, streams, metadata, and results are never uploaded.
Files stay in this browser tab and are never uploaded. Up to 250.0 MiB per file and 10 files.
Lower CRF values preserve more detail and usually create larger files.
The private batch workspace is ready. Video encoding becomes available after the verified browser engine is loaded.
MP4 probe and decode → stream-aware conversion → MKV verify
MP4 input is probed for its video, audio, subtitle, chapter, rotation, color, metadata, and encryption streams before conversion.
MKV output uses VP9 and Opus with compatible Matroska chapters and text subtitles.