swf to mp4 conversion

Hi, I am looking for a tool which can convert my 3 min swf file to mp4; want to download my video to iOS and other handheld devices. It is very important the output video is generated as sharp and smooth as original swf. I have tried many tools available online (free as well as paid) but either the output file is blank/gets stuck or with highly compromised quality. Please help if someone has come across any means to convert swf file to HD quality mp4 output.