Configure closed captioning

Closed captioning (CC) allows the content provider to display text overlayed on the video content thus providing additional information about the video content to the consumers. Closed captioning is primarily used as an accessibilty tool to show a transcription of the audio portion of the video content as it occurs. The term “closed” in closed captioning indicates that the captions are not made part of the video by default. Hence, the captions have to be decoded/extracted by an external tool. Adobe Media Server (AMS) 5.0.1 supports injecting closed caption data into the video stream supporting the following streaming techniques:
  • HDS (Live and VOD)

  • HLS (Live and VOD)

  • RTMP

Closed captioning in AMS is implemented by injecting/embedding caption data within the H264 SEI NALU as specified in ANSI/SCTE 128 2010 Section 8. Adobe Media Server supports industry standard 608/708 closed captioning for video streaming to the following output channels/devices:
  • Adobe Flash Player/AIR (through the OSMF framework)

  • iOS devices (through HLS)

This document defines the input and output workflows, use cases, and configurations for supporting the 608/708 closed caption data in AMS. The closed caption data will be embedded inside the VOD stream and can be viewed through HDS, HLS, or RTMP based subscribers.