In a TV signal encoder device comprising, for encoding a digital TV signal into an encoder device output signal, both having a predetermined dynamic range, an amplitude limiter, a predictive encoder unit for predictive encoding with quantization an amplitude limited signal of a limited dynamic range into a quantized signal having together with quantization noise the predetermined dynamic range, and a code converter for code converting the quantized signal into the device output signal, a forward offset circuit adaptively gives a forward shift to the TV signal so as to avoid undesirable clipping of tip ends of synchronizing signals in the amplitude limited signal. The forward shift and a lower and a higher range reduction of the predetermined dynamic range into the limited dynamic range are preferably equal to a maximum quantization noise level. Instead of the offset circuit, use of an encoder dynamic range defining circuit is more preferred. In this event, a TV signal decoder device comprises instead an inverse offset circuit a decoder dynamic range defining circuit and a level converter.