FFmpeg : Error occurred while encoding audio stream from ac3 to aac
You're using an ffmpeg with a 2-year-old version of libx264.  It's been mostly feature-complete for a while now, but there are still small improvements and fixes happening.

As Mulvya says, get one built with libfdk_aac, since you should update your ffmpeg for libx264 anyway.  Your current ffmpeg is trying to use the VisualOn aac encoder.  That's a terrible choice.

Check the video encoding guide on ffmpeg's Trac wiki, too.  You should probably use -preset slow at least, to get more quality per bitrate. -crf 23 is the default target-quality, which might be more or less than you want.