| 摘要 |
PURPOSE:To perform the changeover of video effectively via simple constitution by detecting the prescribed signal from among voice reproduction signals in a picture switching device switching plural picture signal sources and performing the changeover of the picture source with the use of this detection output. CONSTITUTION:For example, it is used for a system switching and reproducing the picture signal source according to an MIDI(Musical Instrument Digital Interface) signal, and the MIDI signal is transmitted through a reception circuit 1 to a selection circuit 2. The selection circuit 2 extracts a control message from among the MIDI signals, further, 8-bit data byte controlling this sound volume is extracted from among them, and this is transmitted to a fade circuit 3 and a picture signal changeover circuit 4. The fade circuit 3 performs the fade-in and fade-out of the picture signal according to the fade-in and fade-out of the sound volume level in the range where the sound volume level by the data byte is smaller than the prescribed threshold value. The picture signal changeover circuit 4 switches a picture source 5 while detecting the sound volume level is turned to zero. |
