Cropping and resizing using VirtualDub?
 

I'd appreciate comments, positive/neutral or otherwise on this technique for cropping 4:3 videos in VDub after I've deinterlaced them with the deinterlace filter.

1. Crop with the crop filter; make the number of pixels cropped from the sides 33% more than the number of pixels cropped from top and bottom (to retain basic 4:3 geometry).

2. Resize with the Resize filter: Aspect Ratio section to "disabled", then "Absolute", 720x576 (or as required).

3. Save as using the x264 8 bit Preset, SAR of 16:15 (1:1 for 1440x1080).

Thanks for any feedback.

I don't like hairy side edges nor headswitching noise. :)

Rule #1 is do not use VirtualDub2 or FM (pre-2) for this. It has serious errors here, glitches the video, adds green lines, etc. It just cannot handle masking (resize+crop). Stick to VirtualDub 1.9, maybe 1.10.

If you change from 4:3 to 1:1, remember to first crop it to 704x576 before the resize to 1:1. Otherwise AR will be off.

It seems fine to me. Double check those numbers, verify AR with overlay script.

On the 704>720 crop, I must admit I don't understand this. Is the purpose to remove the black sides bars because captures are squashed in a bit by the capture card? So, even though the actual frame is 720 wide, the actual video image part is only inside the black sides, nominally 704 wide?

The crop to 704, then expand to 720, is intended to remove the black sides and restore the capture to what would be on the tape?

In other words, the video part of the frame after capture is actually squashed in slightly, by a factor of 704/720?

Thanks for any insight.

-- merged --

I think I've worked it out, as I realised that that image is of a perfectly round object (engine). So the black sides have to be cropped off and then made 720, and the image becomes round. I suppose the 704 is an average value. In this case, I had to crop off more.

No, cropping to 704 is to get the right aspect ratio, it will not get rid of that junk completely, Never resize back to 720 and never take vdub display as a reference, Either encode 704 with 4:3 flag or resize to square pixel resolution such as 1440x1080.

Thanks Latreche, another question:

I see now the 704 achieves the right aspect; but wouldn't that only be if I then stretched it back out to 720 or 1440 (z1080)? If it still leaves some crud on the edges and needs more trimming, is my technique of proportional trimming of the top and/or bottom to keep the 4:3 valid?

720 is not square pixel resolution nor the right ratio, It's just a capture resolution. If edges are a concern mask them with black borders, or crop off entirely and resize to at least 1440x1080, Anything lower will produce jitter, in other words the higher the resolution the less resizing jitter there is.

OK thanks, got it.

Resizing from 720x480 to 1440x1080 does actually improve quality? Now i try to encode the captured lossless raw (with unpopular HuffYUV_mt) to something more known format like x264 as Hushpower suggested with VirtualDub2, but as i see LordSmurf's VirtualDub 1.9.11 has also a preinstalled x264vfw-H.264/MPEG-4 AVC codec. VirtualDub2 is useless or just the cropping and resizing functions?

I use vdub2 for processing, works fine, It is not recommended for capturing. Also it is more accurate to crop to 704 first before you resize to 1440x1080.