Projects	Metadata - transmission via DVB and MPEG-2

Metadata are all data's that explain video and audio material. They are inserted into the blanking interval and therefore remain part of the video signal. This procedure is similar to the well know analog video metadata such as Time Code, Camera ID's, VPS and WSS. In comparison to analog video, about a thousand time more information fits into the digital blanking interval (used for example with closed captioning data, UMID, camera spatial position data, etc.). Up until recently most of this data has been lost in the transmission, because compression methods usually did not send all available lines, in order to lower data transfer size. Thanks to a standard developed in 2003 (ETSI EV 301 775) some general rules have been specified for transmission of DVB and MPEG-2. These rules enable a few selected areas of the blanking intervals to be included in the transmission routes.

According to this standard, two lines of the vertical blanking are reserved. One line is reserved for VBI-data such as VPS, WSS and closed captioning and the other line for UMID, camera data and user specific data. Available are only the luminance samples which have a maximum of a few hundred "Bytes" per field, which is enough for most potential applications. Of course the above is only possible, if the sending device was designed in accordance to the ETSI norm. For example the Thomson-MPEG-2 encoder/decoder and the Alpermann+Velte data inserter/reader abide by these norms.

Alpermann+Velte has a variety of applications designed with the "luminance-only" concept of the ETSI norm in our Rubidium series modules. Please contact us directly with your project requirements and we will be more than glad to send you a description of how we would design a custom system to suit you needs.