Typical MKV files that need shrinking
Game and stream recordings. OBS Studio and similar programs often save MKV, because a half-written MKV can still be read if the game or the computer crashes. To keep fast action sharp while recording, they use a high bitrate, often 20 to 50 Mbit/s. That is 150 to 375 MB per minute, or many gigabytes for one evening of play. For a clip you want to share, or for an archive of old sessions, that is far more than needed.
Backups and downloads. Copies of discs and some downloaded films are kept as MKV at a very high bitrate. Compressing them to 1080p or 720p makes a library fit on a smaller drive.
What the compressed MKV contains
MKV can carry many tracks at once: several audio languages, subtitle tracks and chapter marks. The compressor makes a simple, compact file. It keeps the video and the main audio track, and the sound is saved as AAC. Extra audio languages, subtitles and chapters are not carried over. If you need them, keep the original as well, or add subtitles again later with Add Subtitles.
Settings for gameplay and other fast footage
- Fast motion needs bits. Racing and shooter games lose detail faster than talking-head videos. Start with High quality and check the 2-second preview in a busy scene, with 2× zoom.
- 60 fps or 30 fps. Keep 60 fps for fast games where smooth motion matters. For strategy games, tutorials or a video where you mostly talk, 30 fps nearly halves the amount of picture data.
- 1440p and 4K captures. Balanced scales them to 1080p, which is what most viewers watch anyway.
- Target size for clips. A short highlight for a chat fits the Discord preset of 10 MB best at 720p, and the tool lowers the resolution by itself when needed.
Choosing the codec
MKV accepts H.264, HEVC, VP9 and AV1. H.264 is the most compatible: smart TVs, media boxes, Plex and Kodi play it without trouble. HEVC and AV1 can halve the size again, which helps for archives, but some older TVs and players can't decode them. The list shows only the codecs your browser can encode. If the file has to play on a phone or in an editor, an MP4 is often easier; use MKV to MP4 for that. To cut a long recording down to the best minutes first, open it in the MKV editor.
Very large files need time and memory. A two-hour 4K capture can take a long time on an average laptop, so a lower output resolution is the quickest way to speed it up.