METHOD AND ARRANGEMENT FOR TRANSMITTING AND RECEIVING ENCODED IMAGES

摘要

TeleWeb services are currently being developed, in which HTML-encoded images are transmitted in the vertical blanking interval of a conventional analog television signal. For special applications, such as subtitling and targeted advertising, the relevant TeleWeb images must be displayed substantially in synchronism with given video frames of the television signal. This is achieved by transmitting the encoded images in advance and provide them with a time stamp (33) which specifies the display time in terms of a reference clock. The reference clock is preferably derived from the teletext clock time (31,32). A possible display time stamp format is hh:mm:ss'ff, where ff specifies a frame within a second. At the receiver end, the teletext clock is interpolated to reconstruct the reference clock, and the subtitles are buffered until the display time stamp matches the actual clock time.