Please, help to convert progressive source to interlaced result

[lovyagin]

Please help! I have a DivX/XviD AVI progressive (PAL 16:9) source and I'd like to convert it to DVD (PAL 16:9 again), but interlaced to make video more motion more smooth as video is to be watched on CRT TV (although avi source is prepared to be watched on LCD computer, captured and encoded from digital satellite tv).

I'm going to encode it using HCenc, so I need to prepare proper AVISynth script to produce smooth motion interlaced video. Please, help to write this script.

[jagabo]

Converting a progressive source to interlaced won't necessarily make playback smoother. What is the frame rate of your source?

[lovyagin]

What is the frame rate of your source?

it's PAL, so it's 25 fps

[jagabo]

Then interlaced encoding won't make it any smoother at all. If it was 50 fps you could pull one field out of each frame to make a nice 25i MPEG file.

WhateverSource() #50 fps source
SeparateFields()
SelectEvery(4,0,3)
Weave() #25 fps interlaced

One possibility with a progressive 25 fps source is to use a frame rate doubler that uses motion vector analysis to create 50 fps. Then pull fields from that. Here's the basic idea for doubling the frame rate:

http://forums.guru3d.com/showthread.php?t=288017

It works well for some types of material, not so well with others.

[lovyagin]

One possibility with a progressive 25 fps source is to use a frame rate doubler that uses motion vector analysis to create 50 fps. Then pull fields from that. Here's the basic idea for doubling the frame rate:

http://forums.guru3d.com/showthread.php?t=288017

Well, thanks a lot for suggestion, I'll try to check it

It works well for some types of material, not so well with others.

In fact, I tried simply to set "interlaced" in HCenc, and it produced better result than simply playing progressive AVI on CRT, (but worse than source that was not de-interlaced). Maybe your way will produce better result?

P.S. video is football match, I can see on it that the ball flies far that it flies like "discreetly", not smoothly.

upd. No chance, this work extremely slow, tripling encoding time on my 2*3.0 GHz CPU... what about doing simply

convertfps(50)
SeparateFields()
SelectEvery(4,0,3)
Weave()

[jagabo]

In fact, I tried simply to set "interlaced" in HCenc, and it produced better result than simply playing progressive AVI on CRT

That should not have appeared any smoother. The chroma channels would be a little blurred though.

what about doing simply

convertfps(50)
SeparateFields()
SelectEvery(4,0,3)
Weave()

If you look closely at the results of that (step through it with VirtualDub) you'll see that every other frame looks like a double exposure (when there is motion). It might look a little smoother during real-time playback on CRT.

[Gavino]

If you look closely at the results of that (step through it with VirtualDub) you'll see that every other frame looks like a double exposure (when there is motion).

I guess you mean every other field.
Each frame will consist of half an original frame in one field and half a blended frame in the other.

[jagabo]

If you look closely at the results of that (step through it with VirtualDub) you'll see that every other frame looks like a double exposure (when there is motion).

I guess you mean every other field.
Each frame will consist of half an original frame in one field and half a blended frame in the other.

Yes, sorry. If he leaves out the SeparateFields().SelectEvery().Weave() he can see the frames before pulling out fields and weaving them. Or he could Bob() the interlaced frames to see fields individually.

[lovyagin]

Thanks you again for suggestion... well, so I'll try to convertfps(50) and tell you result later.

[jagabo]

I'm not recommending ConvertFPS(). Just pointing out what it does. I consider it a severe defect.

[lovyagin]

At last I've tried MVTools framerate doubler -> Selectevery(...).

In fact, I found that this method lefts some artefacts. For example, fast flying ball gly even a little more discreetly. Motion of big object over static background cause background 'following' it and borders become blending. But any way it really makes movie a little smoother and softer to watch saving my eyes.

Although it works a little slow, I will use it. Thanks you a lot again.

[jagabo]

At last I've tried MVTools framerate doubler... I found that this method lefts some artefacts. For example, fast flying ball gly even a little more discreetly. Motion of big object over static background cause background 'following' it and borders become blending.

Yes, all the motion vector algorithms work on square blocks of pixels. A block that is part object and part complex background can't simply be moved from one location to another. The algorithms break down at that point and resort to blending or blurring.