carewe

Hello, I am quite new to this so be gentle! I have successfully copied a couple of cassettes from the cam recorder to my hard disc. The files are in the AVI format and between 12.5 and 18 gbs. The pictures and sound are fine when I play them on my computer, but I cannot copy them to disc (DVD) without them becoming very poor quality. What am I doing wrong? I am sure it must be quite easy but I don't have any experience of videa at all! Any help? Pacaud