If the term refers to the MP4 container or a specific encoding, you might be looking for papers on the standard.
If you are looking for research related to the components of that string, here are the most likely areas of relevance: 1. Video Compression and MP4 Standards 21676mp4
: Search for "H.264/AVC" or "H.265/HEVC" efficiency if the number refers to a specific bitrate or resolution setting. 2. Specific Technical Documents If the term refers to the MP4 container
: A paper ID like 2106.076... might be what you're recalling. : This is a specific international standard regarding
: This is a specific international standard regarding Water quality — Determination of the dissolved fraction of selected active pharmaceutical ingredients . If your topic is environmental science, the ISO 21676 standard is the definitive "paper" on this topic.
: The official ISO page for MPEG-4 Part 14 provides the technical specifications for the MP4 file format.