mkv
What is a .mkv file?
video/x-matroska
MKV (Matroska) is a flexible open multimedia container that can hold virtually unlimited video, audio, subtitle, and attachment tracks with rich metadata and chapters. It is codec-agnostic and popular for high-quality video with multiple audio and subtitle options. It is a superset of the design behind WebM.
How to use a .mkv file
Use an example MKV to test multi-track demuxing, subtitle and chapter extraction, codec detection, and remuxing or transcoding pipelines.