Convert format

Different tools, platforms, and devices expect different video containers and codecs. Final Cut Pro works best with MOV. Android devices play MP4 natively. Some older systems refuse anything but AVI. Video posted to the web should be MP4 or WebM for broadest browser support. Receiving a video in the wrong format for your workflow is common, and installing a converter just to handle it once is overhead most people skip.

The container format and the codec are separate things, but most people encounter them together: MOV files from iPhones use H.264, which plays everywhere. WEBM files from Chrome screen recordings use VP8 or VP9, which many desktop editors cannot read natively.

For MP4 output the tool uses libx264 with CRF 23, yuv420p pixel format (required for wide H.264 compatibility), AAC audio at 192 Kbps, and +faststart for browser streaming. A pad=ceil(iw/2)*2:ceil(ih/2)*2 filter ensures even pixel dimensions required by H.264. For WEBM input specifically, the tool adds -fflags +genpts (which fills in missing or broken timestamps, common in MediaRecorder output) and forces -r 30 to produce a constant frame rate from variable-frame-rate source. For WebM output the tool uses libvpx with libvorbis audio. Other formats use FFmpeg's codec defaults for the container.

MP4 with H.264 is the right output for almost everything: streaming sites, social media, messaging apps, and desktop players all support it. Use MOV only when the destination is specifically a macOS or iOS editing workflow. Use WebM only when the destination is a web page where you control the embed and want the open-codec advantage.

If you are converting a WebM file from a screen recording, the output may be slightly longer than expected because screen recording WebM files often have imprecise timestamps. The +genpts flag corrects this but the timing is approximate.

Handbrake and VLC can convert formats locally but require installation and, in VLC's case, a non-obvious workflow buried in menus. Online converters upload your file to a server, which is a problem for any video with unpublished content, faces, or proprietary information. This tool converts locally with the same libx264 settings a professional tool would use, produces a streaming-ready MP4, and never touches a remote server.