I have an old 720p video file from my video camera that I cropped down to remove some unwanted footage from the top, after which I converted to an mkv. The file is now 1280*688 (or 688p), my new blu-ray player plays MKVs natively, but they have to be standard resolution (1080p, 720p, 576p, 480p). Basically what I want to do is add 16 pixel black bars to the bottom and top of my video file, so that it is playable in my blu-ray player. I've demuxed the audio and video, so I have one AC3 file and the video h264 file that I want to work on. Can anyone suggest an easy way of doing this?