Original Pixel Type vs Square Pixel

in TVAI i see there is an option when upscaling, on the output, option to pick between Original Pixel Type or Square Pixel
what is the difference between Original Pixel Type and Square Pixel? and what use case to choose one or the other (general idea/rule of thumb)?

It comes from this.

Essentially some media like DVDs would store the video with a non square (i.e. not 1:1) PAR (Pixel Aspect Ratio). For example, the PAR might be 8:9.

You can read how to calculate it here.

If we take an example of a video that is stored as something like 720x480, however it is displayed as 720x540 then we can calculate the PAR as:

PAR = (720/540) / (720/480)
PAR = 1.333 / 1.5
PAR ~= 0.889

Adjusting the output option changes how Topaz interprets the stored media file. If you are unsure, you will need to use a tool like mediainfo on your source file(s) to interrogate the pixel aspect ratio and adjust the setting accordingly.

I am not sure i 100% understand you based on the calc if to use original pixel or square and how to calculate?.
Side note: if it’s calculable, can’t TVAI add “Auto” function to make things easier for us? like the did for the Interlaced “Scan Order” module

in my use case (in picture) what option should i use (Original Pixel Type or Square Pixel)?
( old analogue Video8 tapes PAL 576i )


Original pixel type is essentially “Auto.” If you want to retain the aspect ratio of your source (meaning, it already looks correct in VLC), just use that.

In your case, I see 720x576 PAL with a 4:3 ratio. Topaz will read this and retain the proper aspect ratio using original pixel type.

So in this case (my case), do I need to choose Original Pixel Type or Square Pixel?
because when I tried them both, I get different results (with square I get larger picture size with smaller black side borders).

PAR = (4/3) / (720/576)
PAR = 1.333 / 1.25
PAR ~= 1.066664

Personally I have been re-sizing using Handbrake or similar to get a 1:1 PAR and then bringing into TVAI to upscale with square pixels - but that is just me.

You could resize to either 720x540 or 768x576 if you want to have a file with a square/1:1 PAR.

If you want to do it all in TVAI then just ensure the file that Topaz outputs has a 4:3 aspect ratio once any black borders are removed from the calculation - then it should be correct.

I give up trying to understand the Math, let’s leave it…
just if you can give me a simple answer for my question/use case…

for my Videos are of 720x576 (1.25:1) PAL 25fps from a video8 source, desired output 1080p
all processing is done in TVAI. Original Pixel or Square pixel? which one to select in TVAI?
(image is above at this thread/post if you need more details)

The simple answer is you can use either - but it depends what device you are going to play the resultant file on.

A PC with appropriate media player (e.g. VLC, MPC-HC) is smart enough to display the “original pixel” type in the correct dimensions based on reading the metadata of the file, this is also how various devices like a DVD player connected to a standard definition TV should work.

If however you use “square pixel” type - then TVAI alters the dimensions of the file - it will display fine on a PC or similar device, but it may not be correct if you encoded it for a DVD and then connected it to a standard definition TV. You may find the image squished or stretched compared to how it should be.

TL:DR - if you are only ever going to play the files on PC/Mac - I would probably suggest square pixel type for you as TVAI seems to handle correcting the aspect ratio (by downscaling).

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I’m not seeing an option to output with square pixels. I’m upscaling from SD NTSC to 1080p. Any suggestions? It’s for a Blu-ray release.

I think it’s only available/option with Interlace videos.



In my experience, square vs. original pixel type only displays when the PAR is not already square.