MPEG and VBI Originally, the MPEG video compression scheme discarded all VBI information and included only the compressed, active video portion of the picture for transmission. This caused all VBI data to be lost when the video was digitally compressed for transmission using MPEG.
Today, however, enhancements to the original MPEG compression system have provided two methods for including VBI data in
■The first method is to extract the data from the baseband video input and insert that data digitally into the transport stream as either a dedicated PES stream on a dedicated PID, as in
■The second method is to shift, or expand, the active video portion of the picture to include the VBI lines in the compressed picture frame, as in DVB 4:2:2 expanded windows.
For either of these methods to work, it is required that both the encoder and decoder are:
■Functionally capable of processing the required video
■Correctly configured, either manually or via
All of the VBI schemes described in this document, with the exception of Tiernan Proprietary Closed Captions, adhere to industry standards and formats, defined either by ATSC or DVB. Tiernan Radyne ComStream equipment does inter- operate with all other vendor’s equipment that is found to be compliant with these industry standards.
Tiernan’s TDR6 decoder can process data contained in the VBI region of a video signal according to the following methods and standards:
■
■DVB 4:2:2 Expanded Windows – DVB standard for transmission of 16 or 32 lines of VBI data included on a composite analog or component digital (SDI) format video signal. This standard supports both PAL/625 and NTSC/525 format video standards.
72 |
| Tiernan VBI Data Transmission |
