Closed Captioning

Support for closed captioning in Wowza™ media server software enables you to ingest caption data from a variety of instream and file-based sources and convert it to the appropriate caption format for on-demand and live streams using the Apple HLS, Adobe HDS, and RTMP protocols. This feature helps U.S. broadcasters to comply with the Twenty-First Century Communications and Video Accessibility Act of 2010 by providing captioning for television programs that are distributed over the Internet.
 

Notes:

  • You can configure closed captioning in Wowza Streaming Engine™ software and in Wowza Media Server™ software version 3.5.0 and later.
  • In Wowza Streaming Engine software, closed captioning in MPEG-DASH streams is currently NOT supported.

Closed captioning for on-demand streams

A Wowza media server can extract 3GPP Timed Text caption data from MP4 files or from companion files that use Timed Text Markup Language (TTML), SubRip Text (SRT), Web Video Text Tracks (WebVTT), or Scenarist Closed Caption (SCC) formats to specify caption data. This caption data can be injected into Apple HLS streams as CEA-608 captions or into Adobe HDS and RTMP streams as Action Message Format (AMF) onTextData events. For more information, see the following articles:
   

Closed captioning for live streams

A Wowza media server can ingest instream closed caption information from AMF onTextData events or CEA-608 data. A media server API enables AMF onTextData events to be injected into Adobe HDS and RTMP streams. The ingested caption data can also be delivered in Apple HLS steams as CEA-608 captions. For more information, see the following articles:
   

Closed captioning for Apple iOS devices

The Apple iOS subtitling system uses WebVTT, which provides more flexibility in rendering multiple languages and languages that aren't supported in iOS CEA-608 closed captioning. A Wowza media server can convert closed caption data in on-demand and live streams to WebVTT subtitles for playback on Apple iOS (version 6+) devices. For more information, see the following article: