Remove noise garbage from bottom of video.

[mlong30]

Hi All,

I'm sure this questions has been asked, but on NTSC video, how do I get rid/trim off the junk at the bottom of the video when converted from DV source? I want to add it to my AVISYNTH and VirtualDub script? My video is 720x480.

Thanks.

Matt

[Soopafresh]

crop(0,0,-0,-16)#Or try 32,48, etc
Spline36Resize(720,480)

[jagabo]

Soopafresh's

crop(0,0,-0,-16)#Or try 32,48, etc 
Spline36Resize(720,480)

will change the aspect ratio a little and will really screw up interlaced video.

crop(0,0,-0,-16)
addborders(0, 0, 0, 16)

will maintain the aspect ratio and not screw up interlaced video. It will cut off 16 lines from the bottom and then replace them with a black border. If you are making a DVD you won't see the black border because it's in the overscan area.

[Soopafresh]

Yeah, you're right. Forgot about the DV source.

[andie41]

I am using

 LetterBox(0,8)

[jagabo]

Ha ha! I didn't know about that one. It should be faster than crop() and addborders().

[mlong30]

I am using

 LetterBox(0,8)

Can Letterbox be used in Virutual Dub?


Thanks!

Matt

[guns1inger]

You can open the scrip tin virtualdub, but I don't think that is what you are asking.

In virtualdub, add a Null Transform, then open Cropping and remove the noise. Add a Resize filter, and set it equal to 720 x (vertical res - cropped amount), then set the letterboxing to 720 x vertical res - where vertical res is whatever your original resolution was. This is crop off the noise then add back borders.

[jagabo]

You can add cropping to the Resize filter. Cropping will take place before the resize.

[mlong30]

You can open the scrip tin virtualdub, but I don't think that is what you are asking.

In virtualdub, add a Null Transform, then open Cropping and remove the noise. Add a Resize filter, and set it equal to 720 x (vertical res - cropped amount), then set the letterboxing to 720 x vertical res - where vertical res is whatever your original resolution was. This is crop off the noise then add back borders.

Is this correct, for NTSC 720x480 interlaced TFF video? I just need to remove about 10 lines from the bottom.




Also is this the correct order? NeatVideo is a noise filter. I'm not quite sure which order is best for my NTSC 720x480 interlaced TFF video. Any suggestions?



Thanks.

Matt

[jagabo]

Neat video is one of the slowest filters. It's best to give it as little work to do as possible (ie, give it the smallest frame size). So, from that perspective, you have the filters in the best order for what you're doing. But you have several other problems.

If your video is interlaced you have to be careful not to disturb the two fields.

If I remember correctly Neat Video is not interlace aware although it usually works fairly well with interlaced video. Just be aware that it could introduce problems. You could avoid those problems by using the Deinterlace filter with the Unfold Fields Side-by-Side option before Neat Video and the Deinteralce again with the Fold Side-by-Side Fields Together option afterwards. This isn't perfect either but will usually work better.

I can't tell exactly what you're doing with the Resize filter. You should not resize the 720x470 frame to any other size using the top part of the Resize dialog. Doing so will mess up the fields. If you are resizing to 720x470 (ie, the top part of the resize filter is set to 720x470) and letterboxing to bring the frame back up to 702x480 you will reverse the field order of the video. This is because 5 scanlines will be added to the top of the video (and the bottom), shifting the remaining scanlines down by 5 lines. Even numbered scanlines (one field) will become odd numbered scanlines (the other field) and vice versa. If you really want to crop then letterbox, you should crop by a multiple of 4 (crop by 8 or 12 instead of 10) so that the field order doesn't change. Or at least be aware you changed the field order and handle it appropriately later.

In a case like this I would would use a filter chain like this:

Deinterlace -- unfold fields side-by-side
Neat Video
Deinterlace -- fold side-by-side fields together
Fill (overwrite bottom 10 lines with black)

[mlong30]

Neat video is one of the slowest filters. It's best to give it as little work to do as possible (ie, give it the smallest frame size). So, from that perspective, you have the filters in the best order for what you're doing. But you have several other problems.

If your video is interlaced you have to be careful not to disturb the two fields.

If I remember correctly Neat Video is not interlace aware although it usually works fairly well with interlaced video. Just be aware that it could introduce problems. You could avoid those problems by using the Deinterlace filter with the Unfold Fields Side-by-Side option before Neat Video and the Deinteralce again with the Fold Side-by-Side Fields Together option afterwards. This isn't perfect either but will usually work better.

I can't tell exactly what you're doing with the Resize filter. You should not resize the 720x470 frame to any other size using the top part of the Resize dialog. Doing so will mess up the fields. If you are resizing to 720x470 (ie, the top part of the resize filter is set to 720x470) and letterboxing to bring the frame back up to 702x480 you will reverse the field order of the video. This is because 5 scanlines will be added to the top of the video (and the bottom), shifting the remaining scanlines down by 5 lines. Even numbered scanlines (one field) will become odd numbered scanlines (the other field) and vice versa. If you really want to crop then letterbox, you should crop by a multiple of 4 (crop by 8 or 12 instead of 10) so that the field order doesn't change. Or at least be aware you changed the field order and handle it appropriately later.

In a case like this I would would use a filter chain like this:

Deinterlace -- unfold fields side-by-side
Neat Video
Deinterlace -- fold side-by-side fields together
Fill (overwrite bottom 10 lines with black)

My resize looks like the following ....




As far as deinterlace goes. NeatVideo 2.0 I believe I have it configured to deal with Interlaced. Do I still have to seperate the fields?



Thanks!

Matt

[jagabo]

Ah, I see Neat Video has added an interlace option (I only have the 1.0 demo). So you don't need to unfold/fold as I indicated earlier.

Resizing from 720x470 to 720x480 as you're doing it will destroy the video. The two fields will become irreversibly mixed.

By the way, there's no point in enabling the expand and letterbox option if you're already resizing to the final size.

[mlong30]

Resizing from 720x470 to 720x480 as you're doing it will destroy the video. The two fields will become irreversibly mixed.

Then how do I remove the bottom 10 lines without destroying the video?

Matt

[guns1inger]

Crop to 720 x 470, then resize to 720 x 470 with letterboxing of 720 x 480. The letterboxing will fill in the missing lines with black without resizing and destroying the interlacing.

[mlong30]

Crop to 720 x 470, then resize to 720 x 470 with letterboxing of 720 x 480. The letterboxing will fill in the missing lines with black without resizing and destroying the interlacing.

Like this.....





Matt

[guns1inger]

yep

[mlong30]

yep

Thanks! You are the man!

I wouldn't have seen that

[jagabo]

But that reverses the field order as I pointed out earlier.

[guns1inger]

Why will this reverse the field order, and where did you point this out ?

[jagabo]

Why will this reverse the field order

Because the letterboxing will end up shifting the remaining scanlines of the original video down by an odd number of lines. All the even scanlines from the original video will become odd scanlines, and vice versa.

and where did you point this out ?

https://forum.videohelp.com/viewtopic.php?p=1701070#1701070

[guns1inger]

Fair call. Best option then is still to do the cropping/borders in avisynth, then load it into virtualdub to run NeatVideo over it. Teh wait 24 hours.

[jagabo]

Or crop 8 or 12 scanlines (instead of 10) so the image is shifted down by an even number of scanlines.

Or skip the crop and resize and just overwrite the bottom 10 scanlines with black with the Fill fileter.

[mlong30]

Or crop 8 or 12 scanlines (instead of 10) so the image is shifted down by an even number of scanlines.

Or skip the crop and resize and just overwrite the bottom 10 scanlines with black with the Fill fileter.

If I use the fill filter, does it matter if I use a odd or even number?

Matt

[jagabo]

The fill filter simply overwrites parts of the image with the selected fill color. It doesn't change anything else about the image. So nothing you do with it will effect the field order or "contaminate" the fields.

A frame of interlaced video contains two half pictures. One half picture is contained in all the even scanlines, one in all the odd scanlines. When these are displayed on an interlaced device one field is displayed at a time. So it's important to keep track of which field is to be displayed first (the field order), and to keep the two fields from comingling, blending together, or otherwise interfering with each other.