To prevent the generation of speech noise in a monitor device which receives output of a signal switching device.
A cross-point switch 101 selectively takes a serial digital interface (SDI) signal of one series from SDI signals Sin-1 to Sin-m of m-series, based on a switch control signal SWC according to user's operation. When there is no packet (an audio data packet (ADP), an extension data packet (EDP) and an audio control packet (ACP)) relating to audio, in a horizontal ancillary (HANC) data area of the SDI signal which is output from a serial/parallel (S/P) converter 102, an ADP output section 110 and an EDP output section 111 constitute the packet by using audio data from a silent data generating section 106, and a multiplexer 112 inserts the packet into the ancillary data area. Thus, irrelevant to a classification of the SDI signal which is switched by the cross-point switch 101, the output SDI signal of the multiplexer 112 has a packet relating to audio inserted to all ancillary data areas.
SATO KAZUSHI
Eiji Yamada
Eiji Sasaki
Toshio Sawada
Daido Patent Office