Geoff if the display you are working with is indeed a Daktronics display please see the below information as I am a employee at Daktronics and have asked our control software group to help you with your question.
Artwork dimensions should equal the pixel resolution of the display the content is designed for. This will make importing still and animations much faster and ensure images will not appear distorted on your display. Remember Daktronics displays are sized by pixel height and width.
Venus 1500 v3 and Venus 7000 use AVI uncompressed, 30 frames per second and a square pixel aspect ratio. If you have Venus 7000 and the AVI is over 2GB, then the video should be compressed using HUFFYUV or WM9 codecs. If you have Venus 1500 v4, then you can use .mpg, .mp4 and mpeg files in addition to the uncompressed AVI.
There is no charge to contact our helpdesk, so if you have additional questions, please give us a call at 1-800-DAKTRONics (1-800-325-8766).
Hope this helps,
Jameson