: These caption tracks are frequently packaged within MP4 (MPEG-4 Part 14) containers for web streaming and digital broadcast. A/343, "Captions and Subtitles" - ATSC.org
: It is often referenced in the context of H.264/MP4 encoding hardware designed to capture and compress old analog RS-343 signals into digital formats. 3. ATSC Standard A/343 343 mp4
: It was originally designed for closed-circuit television (CCTV) and military displays. : These caption tracks are frequently packaged within