Just create an avisynth script and u can crop it there it one go, tough doing it as post-it said is really cool, fun, and lets u create scenes that u might like better, it does take a lot of time, so in case u just want to do it in one go without hav ing to spend much time u can do it that way..
If ur source is .avi u start like this ur script
avisource("the whole path goes here till ur file.avi")...if ur source is not avi u can check This guide
for more info about avisynth and scripts to import footage, etc...
then, to crop ur footage just add the following line..
Where the numbers u put are what u want out..not the output..if u don't want to change anything on one specific side just put 0..
and in case ur source is interlaced u probably want to make it progressive...there's a lot of scripts with which u can deinterlace and which one u use depends on ur source..u can check this guide
for info about interlaced and progressive sources as well as more about cropping and aspect ratios..then if u just advance further there's also some more about cleaning up footage..
remember to save ur script as .avs...then just open it in virtualdubmod and save ur footage in Lagarith Lossless or import it directly to ur editing software if u can..
by the way...i recommend u to put the scripts to deinterlace and clean whatever u might want to clean before the one to crop...
As another option, tough its not the best choice, you can always "crop" it while editing it in case u don't have any other choice..For example..if ur using Vegas u can go to the Pan/Crop window, select the widescreen ratio and move it to where u want...tough this will make rendering ur video waaay slower and the quality is not gonna be the best one
Hope that helps a lil bit
I'm kinda new in here so I don't know much but i've been investigating a lot recently and cleaning up my footage..