I guess I'll throw this one out there for early comment as well:
We have a large library of codecs and we’ll try to work with almost anything you send us, with minor exceptions (see “What we REJECT”). However, for best results, please refer to the “What We Prefer” section for guidance.
What We Prefer
• Files encoded in AVI, MP4, MPG, MPG2, or M2T formats.
• H.264 or MPEG2 encoded files between 150mb to 250mb.
• Lagarith encoded files (Only for mailed submissions)
• Progressive/Non-Interlaced footage.
Preferred Video Resolutions:
We recommend submitting your video in the exact same resolution that your source material is in, which is likely one of the following:
• 640x480 (4:3, Square Pixel)
• 848x480 (16:9, Square Pixel)
• 960x720 (4:3, Square Pixel)
• 1280x720 (16:9, Square Pixel)
• 720x480 (4:3, 0.9:1 Pixel Aspect Ratio)
• 720x480 (16:9, 1.21:1 Pixel Aspect Ratio)
What We REJECT
• Any SWF, FLV, OGM, MKV, or WMV files.
• Video resolution less than 640x360 (16:9) or less than 640x480 (4:3).
• Audio sample rate less than 44.1khz or a bitrate of less than 128kbps.
• Anything that, despite our best efforts, our software and/or equipment refuses to work with (this is extremely rare).
Anime Expo 2013 - AMV Events Manager
Sakura Con 2013 - AMV Competition Assistant Coordinator
"Other AMV contests [...] have a margin of error. They can write it off as an "oops" and do better next year. AX has no margin for error." -Pwolf
(Lest I ever forget)