1080i to 480i

[Anonymous344]

I am trying to resize a 1080i video stream to 480i, so I can make an NTSC DVD of it. I'm using Virtualdub 1.9.8 to do the resizing with Lanczos3, and there is an interlaced box next to the resizing option. Do I check this box? I plan to resize the file, save as AVI with lagarith compression and send it to HC Enc for encoding to MPEG-2.

Basically, I'm trying to keep the video interlaced. I don't want it to be deinterlaced and then re-interlaced during the conversion process - for obvious reasons.

Can anyone help?

[midders]

My advice would be to use AviSynth as a frameserver for HCEnc; this way you can do the resize and encoding in one go. Personally, I would also recommend that you deinterlace; AviSynth has some excellent quality filters for this.

Slainte

midders

[Anonymous344]

Thanks for your response, but I know how to encode it, and I've already said that I don't want to deinterlace, so that doesn't really answer my question.

EDIT: Sorry, that was a bit snappy. I was just up late, and I hate it when you ask how to do something and someone tells you to do it another way without saying why. My apologies! I shouldn't have been rude.

[poisondeathray]

You can't resize without doing so in an interlace aware method. This basically involves deinterlacing, resizing, re-interlacing

(you can resize in the horizontal dimension safely, but that doesn't help you)

Resizing interlaced fields with a straight resize will create a big mess

I'm not sure if vdub does it correctly with that checkbox

[Anonymous344]

That's a shame! Thank you for explaining that. I felt sure that box would help.

Oh well! Will deinterlacing and reinterlacing work properly? or will the end result look really bad and be a waste of time?

[poisondeathray]

That's a shame! Thank you for explaining that. I felt sure that box would help.

Oh well! Will deinterlacing and reinterlacing work properly? or will the end result look really bad and be a waste of time?

It might work in vdub with that checkbox , I haven't used it (maybe it is deinterlacing and re-interlacing in the background)

There are too many variables to say if it will look "bad" or not; the initial source quality, type of resize, type of bob-deinterlace algorithm, etc...

But one thing is for certain - if you just do a straight resize, you will end up will a bloody mess.

[Anonymous344]

It might work in vdub with that checkbox , I haven't used it (maybe it is deinterlacing and re-interlacing in the background)

Well, it can't hurt to try. If not, I'll investigate the best way to deinterlace and reinterlace it using virtualdub. I have to use vdub as I want to do some precise cropping too.

[poisondeathray]

Well, it can't hurt to try. If not, I'll investigate the best way to deinterlace and reinterlace it using virtualdub. I have to use vdub as I want to do some precise cropping too.

Just a friendly reminder, you can't crop interlaced material either (or you can, but they have to be in mulitples of 4) - so it might not be as "precise" as you want

[jagabo]

VirtualDub does the equivalent of SeparateFields().Resize().Weave in AviSynth. Or in VirtualDub filters, Unfold Fields Side-by-side, Resize, Fold Side-by-side Fields Together. It's not the best method but you may find it adequate. In VirtualDub you should get slightly better result with Deinterlace (Yadif or ELA, double frame rate), Resize, Interlace (progressive).

You will probably get the best results in AviSynth with:

TempGaussMC_beta1mod()
WhateverResize(720,480)
SeparateFields()
SelectEvery(4,0,3)
Weave()

It will be very very slow with a 1080i source -- probably less than 1 fps.

If your 1080i source is YV12 VirtualDub will screw up the chroma channels.

[poisondeathray]

Wasn't there an interlaced YV12 bug in vdub as well, jagabo? (but not vdubmod); when importing files directly into vdub instead of through avisynth

You've mentioned it in a few threads, and put up pretty pictures to illustrate
https://forum.videohelp.com/threads/299341-Disabling-Divx-De-interlacing?p=1829791&viewfull=1

[Anonymous344]

I'll see if the source is YV12, but I don't think it is.

I think I'll follow your method anyway. Do I have to save after each step, or can I do it in one step? Thanks to both you. I really appreciate it.

Just a friendly reminder, you can't crop interlaced material either (or you can, but they have to be in mulitples of 4) - so it might not be as "precise" as you want

Thanks! I have actually done this in the past, but the result looked unusual at times. Now I understand why (although I might have used multiples of 4 by chance lol) Doh!

Well, we live and learn. I'll give Jagabo's method a go.

[jagabo]

Yes, VirtualDub screws up interlaced YV12 chroma channels. VirtualDubMod's internal MPEG decoder handles interlaced YV12 properly, but if you use AviSynth to feed interlaced YV12 to VirtualDubMod it will be handled improperly.

JeffB, most highly compressed video will be YV12. If you can force the decoder to output YUY2 or RGB you won't have any problems with VirtualDub or VirtualDubMod.

If you meant you were going to follow my VirtualDub method -- you can just do the entire thing at once in VirtualDub by adding each of the filters then encoding.

[Anonymous344]

If you meant you were going to follow my VirtualDub method -- you can just do the entire thing at once in VirtualDub by adding each of the filters then encoding.

Yes; I'll do that. Sorry for my imprecision! I really appreciate the help.

EDIT: The thread poisondeathray posted a link too was really informative. That might explain why the colours looked "weird" after I had encoded.

[midders]

Thanks for your response, but I know how to encode it, and I've already said that I don't want to deinterlace, so that doesn't really answer my question.

EDIT: Sorry, that was a bit snappy. I was just up late, and I hate it when you ask how to do something and someone tells you to do it another way without saying why. My apologies! I shouldn't have been rude.

No worries; the reason that I suggested de-interlacing was to get a better quality output. If the resizing/re-encoding process requires that the source be de-interlaced (as poisondeathray suggests), then is there any advantage gained by de-interlacing after the conversion?

[Anonymous344]

No worries; the reason that I suggested de-interlacing was to get a better quality output. If the resizing/re-encoding process requires that the source be de-interlaced (as poisondeathray suggests), then is there any advantage gained by de-interlacing after the conversion?

Well, I was planning to add in other footage that is already 480i (I have removed the pulldown with DGPulldown) in my editing program (Womble) and smart render. I reckoned that if the footage I am adding is 480i I should reinterlace to match, because I understood that NTSC DVDs have to be interlaced rather than progressive or they don't play on some players.

[Vidd]

I suggest using 480p instead of 480i since your source is 1080i.

Sample AviSnyth script:

mpeg2source("video.d2v")
 
SeparateFields()
SelectEven()
 
# Resize
# Filters

Encode the file as MPEG-2 480p, 29.97fps, 720x480. Author and burn.

because I understood that NTSC DVDs have to be interlaced rather than progressive or they don't play on some players.

No.

If video is 24fps, you have to add pulldown flags to 29.97.
29.97 progressive encoded video will play on any dvd player.

[Anonymous344]

If video is 24fps, you have to add pulldown flags to 29.97.
29.97 progressive encoded video will play on any dvd player.

Wow! I didn't know that. That makes my life so much easier. Thanks!

I think I'll still use virtualdubmod as I have to crop the uneven borders and a few pixels of the picture in a precise way and be able to see what I'm doing, if you know what I mean.

[jagabo]

Encoding at 30p will be noticeably jerkier than 30i. If your computer can play a 60 fps xvid file smoothly see the file in this post:

https://forum.videohelp.com/threads/307004-Best-framerate-conversion-%28eg-23-97-to-30-...=1#post1888926

[Anonymous344]

My computer can. That looks odd indeed. Now I suppose I will have to reinterlace. I feel like a pendulum lol.

[jagabo]

That particular video was designed to show the problem at its worst. Sharp, high contrast, medium speed panning shots is where it shows up the most.

[Anonymous344]

In VirtualDub you should get slightly better result with Deinterlace (Yadif or ELA, double frame rate), Resize, Interlace (progressive).

Okay! Just checking the settings. (Virtualdub 1.9.8)

Deinterlace
Interpolate using Yadif algorithm
Double frame rate, top field first? (Or bottom?)

Resize

Interlace
Progressive frames
Odd field first? (or even?)

If these are correct, could I deinterlace, resize, edit my two progressive sources together, export as AVI again, then reinterlace the new AVI before encoding to MPEG-2? Wouldn't it be better to edit the two sources together while they are progressive?

[jagabo]

Double frame rate, top field first? (Or bottom?)

I don't remember. Whichever is correct. After adding the bob step through a shot with smooth motion. If the output frame jumps back and forth you picked the wrong field order.

Interlace - Progressive frames ,Odd field first? (or even?)

Whichever you want. Interlaced DVDs are usually Even (Top) field first but can be either. Be sure to MPEG encoder is set to encoder with the same field order.

If these are correct, could I deinterlace, resize, edit my two progressive sources together, export as AVI again, then reinterlace the new AVI before encoding to MPEG-2? Wouldn't it be better to edit the two sources together while they are progressive?

Not really. As long as you encode with the same settings you can append interlaced video as well as progressive video.

[aedipuss]

I suggest using 480p instead of 480i since your source is 1080i.

Sample AviSnyth script:

mpeg2source("video.d2v")
 
SeparateFields()
SelectEven()
 
# Resize
# Filters

Encode the file as MPEG-2 480p, 29.97fps, 720x480. Author and burn.

because I understood that NTSC DVDs have to be interlaced rather than progressive or they don't play on some players.

No.

If video is 24fps, you have to add pulldown flags to 29.97.
29.97 progressive encoded video will play on any dvd player.

bunch of bullcrap. you don't even know what pulldown does.

24p 3:2 pulldown results in 29.97i. and 30p will not play on ntsc standalones, it's not in the dvd spec.

[Anonymous344]

Not really. As long as you encode with the same settings you can append interlaced video as well as progressive video.

Great! So if I have interlaced 23.976 fps video that I have edited, I can just send it to HC Enc, and as long I set the interlaced options correctly and tick the 3:2 pulldown box I should be fine...

24p 3:2 pulldown results in 29.97i. and 30p will not play on ntsc standalones, it's not in the dvd spec.

Was he perhaps referring to hard-telecined material? (I'm not arguing. I'm just interested. )

[jagabo]

So if I have interlaced 23.976 fps video that I have edited, I can just send it to HC Enc, and as long I set the interlaced options correctly and tick the 3:2 pulldown box I should be fine...

23.976 fps video should be progressive (both fields from the same point in time). Otherwise you will get jerky motion after pulldown.

[Anonymous344]

So if I have interlaced 23.976 fps video that I have edited, I can just send it to HC Enc, and as long I set the interlaced options correctly and tick the 3:2 pulldown box I should be fine...

23.976 fps video should be progressive (both fields from the same point in time). Otherwise you will get jerky motion after pulldown.

Right, so if I have progressive 23.976 fps material, send it to HC Enc and tick the 3:2 pulldown box, that is all that is required to make it play properly on a DVD player. Checking the 3:2 pulldown box interlaces and pulls down the video to the right frame rate.

[poisondeathray]

Jeff B. - Just to clarify, you're now talking about different material than the original 1080i in the 1st post, correct?

aedipuss - I'm think 30p is DVD compliant (I think it's authored with 2:2 pulldown, so 59.94i signal, not sure)

[jagabo]

Right, so if I have progressive 23.976 fps material, send it to HC Enc and tick the 3:2 pulldown box, that is all that is required to make it play properly on a DVD player.

Yes.

Checking the 3:2 pulldown box interlaces and pulls down the video to the right frame rate.

Not exactly. It adds pulldown flags to the MPEG data that gets stored on the DVD. Those flags tell the DVD player how to produce 59.94 fields per second for the TV.

[Anonymous344]

Jeff B. - Just to clarify, you're now talking about different material than the original 1080i in the 1st post, correct?

Well, I was talking hypothetically, because I was thinking about what to do with all my material when it was finally assembled, but you are right yes.

Not exactly. It adds pulldown flags to the MPEG data that gets stored on the DVD. Those flags tell the DVD player how to produce 59.94 fields per second for the TV.

I understand. Thank you!

[Anonymous344]

Yes, VirtualDub screws up interlaced YV12 chroma channels. VirtualDubMod's internal MPEG decoder handles interlaced YV12 properly, but if you use AviSynth to feed interlaced YV12 to VirtualDubMod it will be handled improperly.

JeffB, most highly compressed video will be YV12. If you can force the decoder to output YUY2 or RGB you won't have any problems with VirtualDub or VirtualDubMod.

So this means any m2v you import into Virtualdub 1.9.8 will have messed up chroma if the video is interlaced. If the video is progressive YV12, I suppose there is no problem.

I suppose I shall have to use Avisynth to change to RGB then. I wonder how many people know about this problem...