I imported png files as footage on AE and had it set to 50 FPS when there are 502 frames (which should make it about ten seconds long), but instead, it goes for 20 seconds. To top that, when i try to put music in, it goes twice as fast when i try to put the video to 100 FPS to make the video correct. How do i fix this?
It's really not clear what you are doing, since AE doesn't even support anything more than 99 fps. It simply seems you are not setting your comp framerate correctly and AE - absolutely correctly - converts the framerates for you when you add your stuff, resulting in the bad audio and wrong playback. By all means check your comp settings. If there is anything else, you need to be more specific and precise.