MOV → MKV

It may not. MOV is decoded by dedicated silicon on phones, tablets and TVs, which is why it plays without flattening the battery. MKV typically falls back to software decoding on the same hardware — higher CPU load, a warmer device, and dropped frames on 4K material. For a device target, MOV is the safer container to stay in. MKV has almost no native hardware support — phones, browsers and TVs usually need VLC or a remux before they will play it.

Keep whichever matches where the file is going, because neither is better in the abstract. One of these two is built for playback compatibility and the other for holding everything a file might contain, and they trade against each other exactly along that line. The pragmatic answer for most libraries is to archive in the feature-rich container and export to the compatible one on demand. MOV is the format professional editors ask for, because it survives repeated round-trips through Final Cut Pro, Premiere and DaVinci Resolve without generational loss. MKV is the archival container of choice because it stores unlimited audio tracks, soft subtitles, chapter markers and cover art in one file.

It depends on the MKV container. MP4 defaults to H.264 for the broadest playback support across phones, browsers, and Smart TVs. MKV defaults to H.265 / HEVC for roughly half the file size at equivalent quality. WebM defaults to VP9. The advanced options expose explicit codec choice if you need to override. MKV is Matroska, an open container designed in 2002 with no licensing restrictions and no ceiling on what it can hold.

Yes. When MOV and MKV share an audio codec (e.g. both carry AAC), audio is re-muxed with no re-encode — bit-identical. When the codecs differ, audio is transcoded to AAC / Opus / Vorbis depending on what the MKV container supports. Multi-track audio (commentary, alternate languages) is preserved.

By default yes — a 24fps MOV stays 24fps in MKV; a 60fps MOV stays 60fps. If you need to change rate (e.g. interlaced 29.97 → progressive 30, or 60 → 30 for upload limits), the framerate option handles 3:2 pulldown, deinterlacing, and frame-blending in the same encode pass.

Same-codec re-mux (MOV H.264 → MKV H.264 just changing container): nearly identical size. Codec change can swing dramatically: H.264 → H.265 typically halves the file at the same visual quality; VP9 is roughly comparable; AV1 cuts another 20-30% but is slower to encode.

MP4 / H.264 plays natively on every modern device. MOV / H.264 plays on Apple devices and most TVs but not always on older Android. MKV needs VLC on iOS. WebM is browser-first. The advanced options include a "device compatibility" preset that picks the safest MKV codec / container for your target.

Same-codec re-mux is near-instant — 30 to 60 seconds for a 1-hour file. A full codec re-encode runs at roughly 0.3-0.7x source duration on our GPU pipeline, so a 1-hour MOV → MKV finishes in 18-40 minutes depending on resolution and target codec.

Up to 8K (7680×4320) on Premium plans. Free conversions are capped at 4K (3840×2160) by the per-file size limit. HDR metadata (HDR10, HDR10+, Dolby Vision when present) is carried through where both MOV and MKV containers support it.

Yes. Uploaded video files are processed in isolated workers, never viewed by a human, never indexed, and deleted within minutes of completion. The retention window is documented at /privacy/ and we publish no training corpus from user uploads.

Not in the same step — use /video-trim/ or /video-cutter/ to clip first, then run the MOV → MKV conversion. Chaining trim and convert is faster than re-encoding the entire MOV just to drop unused footage.