21676mp4 100%

: If "21676" is a PMID, it would refer to a very old medical study from the 1940s-50s.

: The official ISO page for MPEG-4 Part 14 provides the technical specifications for the MP4 file format. 21676mp4

: In some cases, strings like "21676" appear in FFmpeg or HandBrake logs when processing video. 3. Potential Misspelling or Truncation : If "21676" is a PMID, it would

: A paper ID like 2106.076... might be what you're recalling. : If "21676" is a PMID

: 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

It is possible the string is part of a DOI (Digital Object Identifier) or a specific database ID. For example: