A video synchronization signal generating circuit includes a sample and hold circuit, a voltage divider and an amplifier. The voltage divider produces an adaptive voltage level based at least in part on an output of the sample and hold circuit. The amplifier, which receives a video signal, is connectable by switches in different configurations. In a first configuration the amplifier acts as a comparator to compare the adaptive voltage level with the video signal. An output of the amplifier in the first configuration is an output of the video synchronization signal generating circuit. In a second configuration the amplifier forms part of the sample and hold circuit.