I've just finished editing a promo video for a company I'm helping out. I had to combine old footage they had with new footage I shot. My problem is that my footage is in HD and 16:9 and the old footage is SD and 4:3. I may have made a mistake in editing the whole video without changing the video before hand. Is there any way I can change the timeline so that that all the video is the same quality and aspect ratio? It is fine to bring all the video to the lower SD footage. Thanks for the help.