subtitle transmission formats

Common standard formatsfor subtitle transmission

There is a range of different formats being used for subtitle transmission. Below is an overview of the common standard formats.

  • In–vision subtitles – This means that the subtitles are keyed onto the video prior to or during the transmission. This can be done for analogue as well as digital SD and HD signals.
  • EBU Teletext – This has long been the standard format for hard of hearing subtitling and multi-lingual subtitling in Europe. The more correct name is CCIR Teletext System B. The current standard name is Enhanced Teletext specification ETS 300 706.
  • WST (World System Teletext) – The same as EBU Teletext, see above.
  • DVB Teletext – The standard for wrapping EBU teletext into a DVB signal. An IRD (Integrated Receiver Decoder) can decode and display this data or re-insert it into VBI for the TV to decode. Today this is the most common method for multi-lingual subtitling in DVB transmissions in Europe.
  • DVB Subtitling – Refers to a subtitle bitmap image that is compressed and sent as a DVB transport stream along with the DVB video and audio and decoded and displayed in the IRD. The latest specification also includes HD bitmap support. This gives the broadcaster full control of the appearance of the subtitles, as well as full support for all languages.
  • Line 21 Closed Captions – EIA-608 has been the standard in the Americas for hard of hearing subtitling and to some extent also used for translated subtitling.
  • EIA-708 – The new standard for HD subtitling for ATSC. It is also backwards compatible with EIA-608.

Edgeware’s Cavena-based subtitling solutions are designed to handle all the subtitle transmission formats used today and to easily adapt to future formats.

Our solutions include OCR Transcoding, using Optical Character Recognition technology to automatically – and instantly – transcode DVB bitmap subtitles to text-based formats, allowing instantaneous OTT delivery in any ABR format, including MPEG-DASH, MSS and HLS.


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