add fading in/out to asf or mp4 h264 video with FFmpeg

We've been looking for a while how to do various things with FFmpeg, instead of learning it all ourselves for a few one of commands it seems easier to list on here! What we have is a video in .asf format in H264 with ACC audio. At the moment we change the container to .mp4 using FFmpeg. We would like you to give us a command or commands that: - - take in an mp4 or asf video (that is H264 with ACC audio) - merge audio file (either mp3 or ACC) (...we already have this, we can provide it, you may know a better way of doing it) -fade audio in (a few seconds from the end, definable amount of time) -fade video in (fade from black) (a few seconds from the end, definable amount of time) - add fade out the audio (a few seconds from the end, definable amount of time) - add fade out (fade to black) the video - and then copy the finished created file to a different folder The fade in audio and fade in from black aren't essential so if this isn't possible we can do without these stages We can provide the merge audio command and a sample video video file. Thanks!