Remove Tilt From Video

[SCDVD]

I have a home video that is tilted a few degrees because the camera was on a tilted tripod when it was shot. Is there a good editor / technique that can be used to straighten it?

[manono]

Hi-

If you're handy with AviSynth, the EffectsRotation function, part of the EffectsMany plugin, can untilt it:

http://avisynth.org/vcmohan/EffectsMany/EffectsMany_index.html

[SCDVD]

Manono, thank you for your answer. Avisynth is a product that I want to spend some time learning later this year when I have the time to dedicate to it. But meanwhile, I'm looking for a GUI editor that has this type of filter in it or available as an add-in.

I see that you are one of the most knowledgeable and helpful members of this forum. I, and I'm sure a lot of others, thank you for you very helpful contribution.

[redwudz]

When you don't want to tackle Avisynth, there is always VD to fall back on. I use VirtualDub Mod most of the time. Rotate2, which I believe is a included filter in VD, should do the trick.

If you dig around a little in http://neuron2.net/ , you will likely find a few more filters that will do what you want. A easier to read listing of many VD filters is here: http://www.thedeemon.com/VirtualDubFilters/

If your source video is DV, you may need a DV codec to do this with VD or VDM. I use the Panasonic DV Codec, then you can output as DV, or use my preferred method, frameserve directly to TMPGEnc encoder.

But if you need to do this more often and you want more control and quality (And speed), Avisynth may be well worth learning. It's not so hard if you use a GUI with it.

[SCDVD]

It's not so hard if you use a GUI with it.

Thanks! Is there a GUI that can be used with Avisynth? I know about AVSEdit, but is there also a GUI shell available?

[SLK001]

You ought to take the 30 minutes or so to get to learn basic AVISynth. Using it in conjunction with VirtualDub(mod(mpeg2)) you can create results that are superior to software packages (like Premiere).

There is a plugin called (I think) AvP - for Aliens vs Predators (also, I think) that gives you GUI-like features.

Here's a basic script that will get you started:

directshowsource("YOUR_VIDEO_PATH\YOUR_VIDEO.AVI") 

bilinearresize(720,480)

ConvertToYUY2()

Yes, it's that simple

[jagabo]

If the video is interlaced (and camcorder footage likely is) you will need an interlace aware rotation filter (VirtualDub's Rotate2 is not) or you will need to deinterlace before rotating.

[redwudz]

jagabo, good point. I have never tried Rotate2 with a interlaced video. Would you have the same problem with Avisynth?

[jagabo]

jagabo, good point. I have never tried Rotate2 with a interlaced video. :oops: Would you have the same problem with Avisynth?

You would have the same problem in AVISynth if you didn't use an interlace aware rotation filter, or didn't deinterlace before rotation. A LeakKernelBOB(), Rotate(although I don't know a rotate filter in AVISynth), SeparateFields(), SelectEvery(4,0,3), Weave() sequence should work pretty well for most material.

[redwudz]

Thanks, jagabo. I haven't had the need to rotate a DV file, but your info will be stored away when that does come up. The same problem would be possible with a MPEG file that needs to be converted to Divx or similar. It all helps.

I'm definitely not up to speed with AVIsynth, but that's one of my future projects. Thanks again.

[jagabo]

redwudz, Here's a thread with some discussion of the technique:

https://forum.videohelp.com/viewtopic.php?p=1681096#1681096

Oh, I see manono gave a link to a filter that can do the rotation.

[awdrifter]

Is there any commercially available product that can do this? I have a similar problem with a video file that I have. The camcorder was tilted pretty badly, Can Sony Vegas or TMPGEnc do this? Because I'm not familiar with VirtualDub or AVISyth. Thanks.

[SCDVD]

I was able to easily remove the tilt in the video I asked about when I opened this thread by using Magix Edit PRO 11. All you have to do after you have loaded your movie is right click on the time line and select "Image Size and Position". It opens a dialog box with a preview window in it. There is a knob you can rotate using your mouse. This rotates the frame by any amount you choose - it's very easy to do. Since there is a preview window you can adjust it exactly as you need it to be. You will have to crop your video after you do this to trim off the edges that are rotated our of the frame.