It's not easy being green - a closed captioning of streaming video case study presented at the SMPTE Australia 2013 Conference in Sydney.
Michael Borthwick CC BY-SA
Loading the player...
Michael Borthwick, former Technical Director at RealTime Health, recounts the journey to closed caption 400 online video clips on the RealTime Health website using the W3C Timed Text format (also known as DXFP). A workflow was developed to convert colour information in the XML DFXP files between broadcast and web colour spaces.
The dialogue of different speakers can be distinguished by using different colours namely white, yellow, cyan and green. This is particularly important for off-screen dialogue. However direct conversion of text specified as 'broadcast' green will not yield text of sufficient contrast in the HTML/CSS specification as understood by web browsers.
The case study examines the resolution of the following four challenges.
- Working around the inability of JW Player to support coloured closed captions where captions are specified by name rather than RGB hex values.
- Identifying a bug in the JW Player captioning plugin (now deprecated) related to rendering of coloured captions over multiple lines.
- Identifying an ambiguity in the appropriate specification of the colour green for web video when caption data originates in the broadcast domain.
- Determining that some proposed schemes to convert caption data from broadcast formats into web formats such as WebVTT and SMPTE-TT (SMPTE-TT PDF) may also be making the assumption that green captions on TV should be styled as CSS green online.
SMPTE OTT Closed Captioning Presentation Transcript Page 1