Hi… Some days ago I was trying to stretch some old dvd from 4:3 to 16:9. When you stretch, you loose some details and there is more aliasing in the video because of the stretching. Now I discovered this trick with Video Enhance AI (doesn’t work anymore with the new Video AI, you have to use Video Enhance AI until 2.6.4). Simply open your 4:3 mkv with mkvtoolnix. Select video and on the right screen select aspect ratio 16/9, and click on start. Now your video is the same but in the info tags you can see aspect ratio 16:9. Open Video Enhance AI and import your video. Now Topaz will recognize your video in 16:9. In fact if you use 100% Denoise/Deblock, you can see that if your real resolution of the video is 640x480, at 100% topaz will give you an output of 854x480. Now the trick is to stretch the video with a model that contrasts the aliasing. You have to select Artemis Aliased & Moire. With this trick, at the end of the processing your video will be stretched and antialiased with the same or more details. Try and let me know
Stretching, as in: all circles become ovals?
No respect for ever stretching 4:3 to 16:9. It looks terrible. As the other commenter said, anythng that is supposed to be a circle becomes an oval. Human bodies and faces are distorted. There is NEVER a legitimate, good reason for doing this.
Why in the world would you want to do that? It would be unwatchable for me.
Coming in late here; there’s definitely a legitimate good reason for stretching. 
It’s amusing how quickly people forget that in the dark old transition days of 4:3 TVs, 16:9 videos would be stored anamorphically as 4:3 where a circle is an oval. The TV would then stretch it out to 16:9 where that oval would then look like a circle.
DVDs, MiniDV, and HDV (which was discontinued around 2011) all stored 16:9 as 4:3 except for HDV’s 720p res which was true 16:9. HDV’s FHD 1080i was 4:3 1440x1080 so if you want to convert that to something more modern you’d have to stretch it out like what a TV would do.
Pretty sure that’s just a matter of obeying the display aspect ratio and such. I don’t think that’s quite what was being suggested here.
I’d be way more interested in an app that would allow me to select something oval shaped that is supposed to be a circle, then adjust the aspect ratio as needed to make it round.
I just wanted to comment that this trick is exactly what I needed. I have video recorded in 4:3 that needs to be displayed in 16x9. The AI does horribly with the funny tall and skinny people in 4:3, but after the correction to 16x9 does fantastically well.
Works in my current Topaz Video AI version, 5.2.1
Just to say the assumption that DAR is always respected is wrong. I have pulled my hair out with software misreading DVD VOB files as the wrong AR and no way to tell Topaz, actually what it should be. Even some 4:3 videos are stored wrongly and I have some that are more close to 1:1 and skinny people. No way to correct this easily (even with software to write the meta data for DAR) as many players ignore it and do their own thing. What we need is simple, allow users to specify the output width and height and if they want the video stretched or black bars inserted. We only get the latter at the minute. Very very frustrating for such a simple ask.
Topaz should give us free scale without letterbox option. It’s my decision how to stretch or squezze a video in width.
like so many other ideas, this one has died a long time ago
