Closed Captioning

Wowza Streaming Engine™ media server software can ingest caption data from a variety of in-stream and file-based sources and convert it to the appropriate format for video-on-demand (VOD) and live streams delivered over Apple HLS, Adobe HDS, and RTMP. Wowza Streaming Engine caption support 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:

  • Closed captioning is supported in Wowza Streaming Engine and in Wowza Media Server™ software 3.5.0 and later.
  • In Wowza Streaming Engine, closed captioning in MPEG-DASH streams is currently not supported.

Closed captioning for on-demand streams

Wowza Streaming Engine 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:
 

Closed captioning for live streams

Wowza Streaming Engine can ingest instream closed caption information from AMF onTextData events or CEA-608 data. The Wowza Streaming Engine Java 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:
 

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. Wowza Streaming Engine can convert closed caption data in VOD and live streams to WebVTT subtitles for playback on Apple iOS (version 6+) devices. For more information, see: