Patent ID: 7006115

Claim:
A method of generating a plurality of horizontal line demarkers in a vertical blank (VBL) region, said VBL region being present in a display signal received by a digital display unit, wherein said display signal contains a plurality of horizontal lines of unequal length in a vertical active (V-active) region, said method being performed in said digital display unit, wherein said display signal comprises a plurality of pixel elements accompanied by a DE signal, wherein said DE signal indicates whether said plurality of pixel elements are being received or not, wherein said determining comprises counting a number of clock cycles between two edges of said DE signal, said method comprising the steps of: determining an expected length of horizontal lines based on said plurality of horizontal lines received in said V-active region, wherein said determining comprises computing an average length of at least some of said plurality of horizontal lines; generating said plurality of horizontal line demarkers in said VBL region according to said expected length; storing a plurality of samples of said DE signal and associated pixel elements in a first-in-first-out (FIFO) buffer, wherein said plurality of samples are stored in an input of said FIFO and retrieved from an output in a FIFO manner; and determining that said display signal is in said VBL region by examining a sample received from said output of said FIFO and at said input of said FIFO wherein a last demarker in said VBL region computed according to said average length is ahead of a positive edge of said DE signal, wherein said positive edge indicates entry into said V-active region, and said method further comprises: examining said input to determine that said positive edge is received; and generating a last one of said plurality of horizontal line demarkers according to said positive edge instead of said last demarker.