Unlike a standard MP4 file that requires a complete "moov atom" (metadata header) at the end of the file to be playable, uses Fragmented MP4 (fMP4) . This allows video to be played back as it is being recorded or streamed, making it ideal for: Live Previewing: Real-time camera feeds in web dashboards.
To function as a "live" feature, the file must be generated with specific flags: MPEG-4 Part 14 (fMP4).
use ffmpeg to connect to rtsp ip cam [✓] stream copy mp4 video from the source [✓] make an mp4 parser node (to get the mime, init, Node-RED Forum