MKVtools 3.6.6 (macOS)
MKVtools is a collection of tools used to manipulate video files. It's primary purpose is to convert mkv files into more user friendly formats for playback on a variety of hardware. MKVtools is trialware - only $4.99 for full functionality, though it will function unregistered, with some minor limitations.
Convert videos to either .avi files or .mp4 files.
Extract the selected .mkv tracks as individual video, audio and/or subtitle files.
Intuitively select desired video, audio and/or subtitle tracks to procces, with the ability to verify the selections using video preview.
Use presets for one step encoding or passthru copying for playback on a variety of hardware.
Embed selected subtitle track (i.e., hard subtitles) into the video.
Control the font, size and positioning of the embeded subtitles.
Split .mkv videos into sections of a specified file size or by start/end time.
Extract or delete tracks from .mkv files.
Join, mux and change the pixel aspect ratio of .mp4 videos.
Add jobs to a queue either individually or in batches via drag and drop so you can process multiple files overnight (registered copies only).
OS X 10.7 or Later