To crop or not to crop?

[mshoward82]

My video is 1080p (1920x1080) but it has the black bars on the top and bottom. And i'm resizing it down to 1280x720 to meet my target file size.

My question is though, is it better leave the black bars and save the the 1280x720 resolution or crop it and have it be 1280x544? Or whatever the cropping comes out to be.

Also, does cropping the extra reduce the file size if I keep the bit rate the same?

[nurbs]

Unless you have a specific reason to keep the black bars you should crop them. (for instance Blu Ray itself only allows some resolutions like 1280*720)
Cropping can't reduce filesize, since size = bitrate * duration. You video will have better quality at the same bitrate if you crop, since there is less area to encode and you lose the transition between the content and the black bars which doesn't compress well.

[mshoward82]

Ok cool. I don't have any plans for bluray. Just encoding with x264 in a MKV container for computer playback.
I always have been cropping but just wanted to check.

Thanks

[Ghitulescu]

Black bars don't require so many bits so to adversely affect the bit budget. Since I don't watch anything on PC I would keep them as they are. Remember, if something happens to your original, you need a second reencoding to "uncrop" it to standard frame sizes.

However, no one can tell you what to do. You may want to reencode twice, one for 16:9 (matted) and one for 2.35:1 (cropped), and compare both. Then pick one options, once for all.

[Selur]

Black bars don't require so many bits so to adversely affect the bit budget.
At least not too much,... (encoding 3:55min of a normal DVD)
mencoder -dvd-device "D:\TestDVD" dvd://1 -chapter 1-1 -ovc raw -noskip -vc mpeg12 -field-dominance -1 -vf yadif=0,crop=720:424:0:76,scale,format=i420 -forcedsubsonly -noautosub -nosound -mc 0 -lavdopts threads=8 -really-quiet -fps 25 -aspect 1.7775:1 -of rawvideo -o - | x264 --preset slow --qp 18 --sync-lookahead 28 --sar 1422:1000 --fps 25 --input-res 720x424 --output "D:\Encoding Temp\cropped.mp4" ---> Output size: 29MB

mencoder -dvd-device "D:\TestDVD" dvd://1 -chapter 1-1 -ovc raw -noskip -vc mpeg12 -field-dominance -1 -vf scale,format=i420,yadif=0 -forcedsubsonly -noautosub -nosound -mc 0 -lavdopts threads=8 -really-quiet -fps 25 -aspect 1.7775:1 -of rawvideo -o - | x264 --preset slow --qp 18 --sync-lookahead 28 --sar 1422:1000 --fps 25 --input-res 720x576 --output "D:\Encoding Temp\uncropped.mp4" --> Output size: 29.6MB