Your project is Progressive, not interlaced.

Did you also tried with other ways of resampling than the project choice?

I want to leave smart resample, because the image is smooth.

When I run old Vegas Pro 11 with the same settings everything is ok,

Your project is Progressive, not interlaced.

 

Normally it is interlaced (Blu-ray), now I set it progressively, so that you can not see interlacing.

Changing your project properties above the horizontal rule does not change your Source Media, wishful thinking or not. Your Project must MATCH your source media first. There's a button for that.

You cannot speed up or scale, and deinterlace simultaneously Those are two hierarchical steps.

You "can" change a chicken into a cow in this business, but it takes more than one operation. And in the right order.

:-o

Deinterlace and render by correctly setting your RENDER template.

Import your deinterlaced intermediate and speed up, rescale, or whatever.

Render your progressive product.

Be sure to keep render quality at Best and I prefer " Interpolate " to "Blend" as a deinterlace method.

Can you share that example project and media? (e.g. on Dropbox, Google Drive, OneDrive, mega.nz, wetransfer.com or mediafire.com) Lower Vegas version project would be better.

The same project in VEGAS PRO 11, the same settings (mixing frames is good):

I provide a link to projects from Vegas pro 11 and 14:

https://drive.google.com/drive/folders/1QFJeWQq_DUyB1Z0FzZsuj9aTr2r3UcGd?usp=sharing

Please compare the rendered portions of the movie VP11.mp4 (from Vegas pro 11) and VP14.mp4 (from Vegas pro 14).

Please compare the rendered portions of the movie VP11.mp4 (from Vegas pro 11) and VP14.mp4 (from Vegas pro 14).

Rendered both to????
Template please!

Please compare the rendered portions of the movie VP11.mp4 (from Vegas pro 11) and VP14.mp4 (from Vegas pro 14).

Rendered both to????
Template please!

 

See the link, there is a template and source file, In Vegas Pro 11 run the VP11.veg file, Vegas Pro 14 frames are badly mixed (even those projects with VP11)

In Vegas Pro 11 run the VP11.veg file, Vegas Pro 14 frames are badly mixed (even those projects with VP11)

I loaded 11 project in Vpro 12 and the 14 project in Vpro 14.
And now to compere something I have to render to a file.
I like to know wihich file I have to render to, which codec and what template.
With template I don't mean the projectsettings , they will automatic being transferred by loading your vegs

I don't have VP11. In VP12-16 there is an ugly "pulsing" as you describe. I recreated the project in VP10 and there was no pulsing, but personally I did not like the result, which was neither sharp nor a proper blend between frames.

Anyway I think you're probably approaching this the wrong way. What is your delivery destination? Blu-ray? YouTube? File on USB stick? Do you want a 50i/50p smooth "TV" look or a 24/25p "film" look.

I see that you are a professional, you see the problem.There is one more solution to use the Video supersampling, unfortunately supersampling often causes the entire program to hang during rendering.

Normally the project is HD 1080-50i (1920x1080; 25,000 fps) Field Order Upper field first

My delivery destination DVD 720x576 25i, Blu-ray 1920x1080 25i and USB mp4 1920x1080 25i (Interlaced).

I'm not really sure what to suggest. If your source is interlaced and your delivery is interlaced then there should not be a need to deinterlace during the workflow. From what I can see, VP12-16 just makes a really bad job of speeding up interlaced footage. VP10 is slightly better but not great. I can't make VP12-16 give the same result as VP10. There might be a possible workflow via a 50p project and/or 50p intermediate that will improve the final result.

I think that Vegas Pro 9-11 gives a satisfactory result

I hope that someone from MAGIX will read this thread, and the interlace error that appeared in VEGAS PRO 12 will be removed.

There is one more incomplete solution Clip Properties Undersample rate change to 0,999