Handbrake: To Crop or Not To Crop

[meldavid]

First off I'm very new to X264 encoding, but fairly good with Xvid encoding thanks to DJ Rumpy's tutorial and advice from this forum.

The last few encodes I have been experimenting with have been using Handbrake to make X264 mkv files, using the Constant Quality Rate Preset with a few changes:

Deblocking set to 0 | 0
No Fast-P-Skip and No DCT-Decimate ticked

I'm a lil unsure of whether to crop the video though because the last DVD I encoded, Automatic crop took off only 2 pixels at the top, and 2 pixels on the right side. So the resultant mkv was 718 x 574 (not Mod16) and filesize was 1798MB.

I re-encoded with the exact same settings, but this time with absolutely no cropping so the resultant mkv was 720 x 576 and file size was 1769MB (slightly smaller! huh?!).

Finally I re-encoded with the same Autocrop of 2 pixels from the top and right, but this time I set Anamorphic to loose and video width to 720. So the resultant mkv was resized to 720 x 576 and filesize was 1812MB (slightly larger as expected).


Could somebody enlighten me which of the three methods above would be the best to use?
My own opinion is that resizing a video, even from 718 pixel width to 720, would actually result in quality loss than just keeping the 2 pixel letter/pillarbox, due to image quality lost from resampling. And from my one test above it shows that you actually get a smaller filesize when not cropping.

Also I miss VirtualDub's feature of being able to encode certain portions of the video with higher/lesser quality.

What are your thoughts?

[creamyhorror]

If you're only taken 2 pixels off the top and 2 off the side, then I think it makes sense to leave it uncropped. If you need to crop (due to big borders), then overcrop to mod16. That said, I've cropped and resized to mod16 before.

I've heard of a similar case, and I think the response from the x264 developer was that non-mod16 cropping might be affecting encoding decisions that cause a small effect. It's also possible that, while your filesize is smaller, your quality (however you measure that) isn't exactly the same. Maybe other folks can weigh in.

If you want to encode different segments with different quality, MeGUI's x264 zones feature is probably what you want. I don't know if Handbrake offers it.