~/talk

Parsing CEA-608 Captions from FMP4s

on YouTube 08m
Talkat Demuxed 2018 · 2018-10-17..10-18· [web-platform, web-performance]

speaker

name:Lahiru Dayanada
links:none on file

resources

video:https://youtu.be/0yTYNIajBQM
slides:none on file

summary

Explains how CEA-608 captions are actually extracted from FMP4s by locating SEI NAL unit type 6 inside mdat boxes, mapping those NAL byte offsets to track samples using baseMediaDecodeTime and sample durations, and converting composition time offsets into presentation times; timing comes from end of caption commands inside the 608 payload, so captions get concrete start/end numbers (example segment yields start 1 end 4). Includes the parsing recipe and where to find the fields in movie fragment/track run boxes.

AI-written summary · about

chapters (4)

  1. 0:00Intro
  2. 0:37What are CEA608 captions
  3. 2:25Example
  4. 7:40Resources

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