Let the encoder adjust aspect, not virtualdub. If the input is NOT a standard aspect, tmpgenc can adjust, and letterbox as needed. 576x240 is (almost) 16:9 widescreen. That's your input. If you want it to look proper on your TV, you need to let tmpgenc have a 16:9 input, and 4:3 output, and keep aspect ratio 2, so it's not squished, stretched, or cut off. 4:3 output is a standard tv aspect. If you have a widescreen tv, you can use 16:9 output to get widescreen video. Again, tmpgenc will adjust. Input and output screens are not out of whack, they show exactly what you're inputting, and outputting. Go to Options, preferences, and enable Auto window resizing.