Honored Contributor
Honored Contributorall i can do is help you to solve the problem step by step by using knowledge that iv got. are you using your own written module? or is the converter module some quartus megafunction or something? in any case, check your VGA's "G" wire. there are 3 analog signal wires R,G,B. in most cases the signal architecture is such that the Vsync is mounted into the G wire. put an oscilloscope probe there and check if the signal is present, once in every 64 microseconds you should see it. if its there, this means altera processor recieves the signal but fails to decode it. there is one more thing, if the vsync is provided seperately,by the device from which you recieve the image, then put a probe on it, check if there is anything inside there. if there is a Vsync signal, and your quartus module fails to read it, you should analyze the entire frame signal and generate your own Vsync from it. iv done it; i had clean pal signal, with Vsync embeded in it. so i captured the vsync region and generated my own vsync impulse from it. in short it is possible. but i havent recieved vga format so i do not know how exactly your vsync looks. if you could tell me a standart name for your format (like "IEEE some number" or "ITU some number", if i remember correctly, company VESA was developing VGA standarts...) that could help us to search the signal's architecture and find out how the vsync is provided.
look, http://www.leadsdirect.co.uk/technical/svgawiring.html here the connector provides vsync impulse by seperated pin (N14).maybe you should try to capture it in the register and write a code to recombine it with the image you get after convertion. if you want it this way, lets go through it step by step. thats all i can do.
