Screen Subtitling

Drop Shadow

Ghost Stripe

No Outline

DVB stands for Digital Video Broadcasting is a consortium of broadcast industry companies. DVB technology delivers digital channels in a multiplex and relies on the viewer having a suitable digital receiver either as a standalone Set Top Box (STB) or built into their Digital TV set. The transmission method may either be digital terrestrial (DTT), satellite, or cable distribution. Not all receivers support DVB subtitles.

Details

The DVB standard (EN 300-743) defines a bitmap based subtitling format. A DVB compliant stream can also carry Teletext data and Subtitles, see Here.

Subtitles are generated as a graphical bitmap and then encoded and compressed into the DVB delivery format). The subtitle data is multiplexed with the video, audio data and possibly other subtitle languages and then transmitted as part of the station's output transport stream to the viewer's decoder. Once a decoder receives the data the subtitle is re-constructed in the decoder's memory. A user can select whether to display subtitles or not and, if available, which one of several languages. At the appropriate time the decoder will then display the subtitle on-screen.

For more technical information about DVB subtitling download our White Paper

Because the subtitles are delivered as a graphical bitmap, unlike the character code based Teletext and US style Closed Captions formats, there is no restriction on the languages that can be supported. This is an advantage when new or special characters need to be added such as the Euro symbol or new Chinese characters.

It is also possible to create special characters or logos but there are some restrictions on image size and colour depth.

Because the DVB multiplex can carry multiple subtitle streams multiple languages can be supported

Other uses of DVB subtitles

Logos - it is also possible to create special characters or logos but there are some restrictions on image size and colour depth.
Menus - it is possible to use the same technology to send menus and other on screen text in multiple languages in a single stream. This allows local headends to have different languages displayed for thier local viewers.
Local alerts and emergency messagegs - DVB subtitles can be used to deliver messages targeted at specific local regions in a single national broadcast stream.

DVB Subtitles

Global Language Support

Bengali

Traditional Chinese

Arabic

Standard Definition Output Styles:

Click on image to enlarge to see how the final output would look at full resolution.

Example 720p HD Output Styles:


	Drop Shadow		Outline

	Ghost Box		Ghost Stripe

Click on image to enlarge to see how the final output would look at full resolution.

Example 1080 HD Output Styles:


	Text Outline


	Solid Stripe

Click on image to enlarge to see how the final output would look at full resolution.
Note: Not all browsers show the full resolution image correctly. Right click on the large image, save the picture as a file and then open with an image viewer for the best image quality.