Cropping double letterboxed films using ffmpeg.

[ShaolinMapache]

So I finally figured out a good command that will crop a video making it display perfectly in VLC with no letter-boxing at all.
I have used it to fix my DVD and VHS rips that were in the wrong aspect ratio and I wanted to share this useful command with everyone.

Open the terminal where your file is located and type:

ffmpeg -i 'filename.mkv' -c:a aac -c:v libx264 -b:a 128k -crf 18  -vf cropdetect 'output.mkv'

After a about 30 seconds press ctrl + C to end the crop detection.
Replace cropdetect with crop output. In my case it was crop=528:304:58:82

ffmpeg -i 'filename.mkv' -c:a aac -c:v libx264 -b:a 128k -crf 18  -vf crop=528:304:58:82 'output.mkv'

The -b:a 128k is the audio bitrate and you can change that depending on your file. 
I hope this helps some people out when making customs.
I am still learning this program but it can be very useful I plan to use it to clean up some of the compression artifacts that the DVD format is known for.  

[SMK]

Thanks for the tip, very cool of you to share. I use VLC myself as a player on my PC, Phone and Fire TV. 

[ShaolinMapache]

9 minutes ago, SMK said:

Thanks for the tip, very cool of you to share. I use VLC myself as a player on my PC, Phone and Fire TV. 

Something cool I learned about VLC recently is you can add film grain if you go to Tools -> Effects and Filters -> Video Effects -> Film grain.

I love a bit of grain so I usually have it on. 

[SMK]

HAHA, very nice. I have no problem with film grain, it adds a bit of charm to a movie.