TV subtitles have been an established service for decades. However, Internet subtitles for live streaming typically have been limited to proprietary solutions. In the near future this situation may improve drastically, thanks to two standards which together facilitate live streamed subtitles: MPEG-DASH for dynamic adaptive streaming and EBU-TT-D (EBU Tech 3380) for distributing subtitles.

Public sample streams

IRT, the Research Center of the public broadcasters in Germany, Austria and Switzerland, in close cooperation with content delivery network (CDN) Provider Akamai, the IPTV and over the top (OTT) solutions provider Keepixo as well as the German public broadcasters Bayerischer Rundfunk (BR) and DasErste now provide two sample live Internet streams to demonstrate the potential benefit of these technologies. The work was carried out in the scope of HBB4ALL, a European co-funded project on media accessibility in a connected TV environment. The implementation shows how future multi-platform access to live streams with subtitling can be realised.

Two scenarios

Any online device can access the same service. The service is not limited to PCs and mobile devices, but also encompasses future Smart TVs based on HbbTV 2.0. This works because MPEG-DASH and EBU-TT-D are natively supported by the latest version of HbbTV, 2.0. The demo streams are publicly available for anyone interested. The first sample consists of a semi-live looped stream. The second stream encompasses a typical, traditional broadcast scenario with a live broadcast signal in HD-SDI which contains subtitles embedded as teletext according to SMPTE ST 2031.

The sample streams are shown on the IRT website. They use the open source DASH IF reference player and Bitmovin’s Adaptive Streaming Player: 

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