Change aspect ratio of x264 mp4s

[TheResidentEvil]

I made some mp4s and I thought I was putting in a 16:9 resolution and apparently I was not. I have already encoded the files in handbrake and when I used to use XviD, I would just load up the avi in mpeg4modifier and change the display AR. This would allow me to fix the file in no time and not have to re-encode. Is there anything similar I can do for these files?

[LeXXuz]

You can use h264info to change the AR setting of your stream.

[poisondeathray]

Other options include changing the SAR in MP4BOX (YAMB) for the .mp4 container, or the DAR in MKVMERGE (MKVMERGEGUI) for a .mkv container

[plonk420]

in h264info, do i use the Output Aspect Ratio section for 40:33 or 32:27 data? or do i calculate the resolution and put it in that section? (like 853x480)