Subtitling is used mainly for two things, to make foreign language material accessible and to aid hard-of-hearing people. Subtitling for translation allows a broadcaster to reach multiple language target audiences. The viewer can select the language of their choice to receive and made visible on the screen. For hard-of-hearing people subtitling allows them to follow. Therefore subtitling is often a legal requirement in many countries.
Subtitling is in many parts of the world referred to as closed captions, CC, which means a choice to view the subtitles/captions or not, compared to Open Captions, which are captions/subtitles always visible. Always visible is also referred to as; in-vision or burned in subtitles/captions. The “CC” logotype is well-known for American viewers, click the CC button to turn the captions on. Why use subtitling instead of audio dubbing? The overwhelming advantage of subtitling/closed captions overdubbing is cost.
Subtitling is many times cheaper per language to produce than alternative language audio tracks. Also, a new subtitling language can easily be added whenever needed, even after all preparations are done. Subtitling is not an exact translation, because the difference between countries and languages often require additional information to understand the original content. And subtitling usually compresses the speech to fit the same information spoken into as little language specific readable text as possible, so the subtitles do not distract the viewer.
How subtitling work?
Subtitling is comprised of three parts – preparation, transmission and distribution.
The preparation of the individual subtitle files, along with the timecode required to synchronise the subtitle with the video. This is done ahead of transmission, either by trained in-house subtitle translators or specialist subtitle preparation companies. The files are delivered to the transmission site in a format defined by the broadcaster and stored until needed for transmission.
There are many different formats to handle prepared subtitle files, but still, the essential information is; text with timecode. Some formats like SRT (SubRip file format) are just text and timecode while other contain a range of attribute information, like position, horizontal and vertical, colour, size, font, etc. Subtitle transmission is an automated process using the standard Cavena equipment.
The Cavena interfaces to planning and automation systems to receive programme information and trigger commands. The transmission units then synchronise the subtitles for play-out using the time code read from the video signal. Subtitles are output in one or more formats depending on transmission platform. Conventional technologies are; DVB, in-vision and EBU Teletext and in the USA technologies are referred to as EIA 608 for SD and EIA 708 for HD quality.
Transcoding
Cavena also provides subtitle transcoding solutions for conversion between transmission formats. This is integrated into our transmission products, so our STU (Subtitle Transmission Controller) play-out unit can switch between timecode-synchronised subtitles file play-out and transcoding from one subtitling format into another. STU also supports live subtitling inputs.
What equipment is required?
This all depends on what is installed or what is to be installed, and the technology used for distribution of TV, film, video all with subtitles. At the playout centre, the main subtitle components are;
- Storage, QC check and archiving with Cavena SAM (Subtitle Archive Management System)
- Transmission control and automation interface with Cavena STC (Subtitle Transmission Control).
- Playout of subtitles with Cavena STU (Subtitle Transmission Controller).
A graphics insertion board for in-vision/burned in/open captions subtitling. A subtitle MUX for distribution of DVB bitmap subtitles. Connection to the main distribution MUX can be ASI or IP multicast. Subtitle Preparation For subtitle preparation, the Cavena TEMPO is an advanced and flexible PC based system with all features needed to create high-quality subtitle files.
Cavena is specialised in subtitling, we have assisted many customers when it comes to design and configuration of cost-effective subtitling solutions and installations, including back up facilities. Time-code or transcode? Cavena can help you with Subtitling! Why choose Cavena? Cavena is one of the worlds longest established and most experienced subtitling solutions providers, and can supply and support the complete range of subtitling.
Cavena has the experience, the background and the know-how to put together the most cost-effective, flexible, quality? And the highly reliable day-in-day-out system for the best end-user experience. Cavena systems are in constant use worldwide with a large number of broadcasters, both regular TV broadcasters and for example broadcasters using the OTT network. All with widely differing requirements, so we can specify what your needs to service your requirements.
At Cavena, we also take great pride in our product support, ensuring a very high uptime. Cavena systems are very flexible, allowing new languages and channels to be added with minimal or no disruption.
