MKVCleaver is a free and open source VFR detection application.
Here are some screenshots to illustrate the features and user interface of this application:
Batch extract tracks, attachments, cuesheets, timecodes, chapters, tags. Screenshot of MKVCleaver - 1832px · 1587pxInterface for MKVExtract to extract data from MKV. Screenshot of MKVCleaver - 1832px · 1587pxDesigned to extract data from MKV files. It can be used in a batch mode. Screenshot of MKVCleaver - 1832px · 1587px