MKV vs MP4
Both are containers, not codecs, and both usually hold H.264 or HEVC video. The difference is in what else they can carry and who can open them.
| MKV (Matroska) | MP4 (MPEG-4 Part 14) | |
|---|---|---|
| Standard | Open, royalty-free spec by the Matroska project | ISO/IEC 14496-14 standard |
| Video codecs | Practically any: H.264, HEVC, VP9, AV1, ProRes, MPEG-2… | H.264, HEVC, AV1, MPEG-4 (VP9 allowed but rarely supported) |
| Audio codecs | Any: AAC, AC-3, DTS, FLAC, Opus, Vorbis, PCM | AAC, MP3, AC-3, ALAC; Opus/FLAC with patchy support |
| Subtitles | Multiple styled tracks (ASS/SSA, SRT, PGS) | Basic timed text (mov_text) only |
| Plays on iPhone / Safari | No (without a third-party app) | Yes |
| Social uploads, editors | Often rejected | Accepted almost everywhere |
| Crash safety while recording | Readable up to the crash | Unreadable if the index was never written (unless fragmented) |
| Best for | Recording, archiving, multi-language releases | Sharing, phones, editing, the web |
The practical answer
Keep MKV when you need several audio languages, styled subtitles, or lossless audio like FLAC and DTS, or while recording. Use MP4 whenever someone else, or some other app, needs to open the file.
Moving between them is usually a remux: seconds, no quality loss. Only unusual codecs (Vorbis, DTS audio; VP9 video) need re-encoding for MP4.
Questions
Is MKV better quality than MP4?
No. Quality comes from the codec and bitrate. The same H.264 stream looks identical in MKV or MP4.
Should I record in MKV or MP4 in OBS?
Record in MKV (or OBS's fragmented MP4 option): if OBS or your PC crashes, an MKV stays playable up to the crash, while a plain MP4 without its final index is unreadable. Remux to MP4 afterwards.
How do I convert MKV to MP4 without losing quality?
Remux it. If the video is H.264 or HEVC, our MKV to MP4 converter copies the stream into MP4 without re-encoding.