Abstract: A system and method for synchronizing audio from a program source with closed captioning data includes a caption encoder having a video-audio delay line. The caption encoder with the delay line is adapted to delay the programming source by a settable amount of time so that the program audio can be synchronized with closed caption data received from a remote live captioner.

Abstract: A system and method for synchronizing audio from a program source with closed captioning data includes a caption encoder having a video-audio delay line. The caption encoder with the delay line is adapted to delay the programming source by a settable amount of time so that the program audio can be synchronized with closed caption data received from a remote live captioner.

Abstract: A composite synchronization extraction circuit is particularly suited for receiving composite video signals containing closed captioning data in raster scan line 21 by means of a signal CMOS integrated circuit device. A dual mode voltage clamp is realized in CMOS technology. The clamp includes temperature compensated current sources in the form of complementary current mirrors through which a clamped composite synchronization node of is charged and discharged, the output of which controls a transistor for charging the composite synchronization node. Detected pulse amplitude is set by slicing the incoming pulse at the back porch level and then doubling the amplitude with an amplifier and comparing that level with the back porch level as derived from a sample-and-hold device. The slice voltage level is maintained without an off-chip capacitor by an analog-digital-analog conversion process.