SD Pixel Aspect Ratio

Topaz is using the wrong Pixel Aspect Ratio for upconverting 720x486 to HD. It says 0.89:1, but the correct number to use for the conversion is 10/11 (0.909:1). This error is causing the resulting videos to be slightly too narrow (squeezed). It should be the same PAR whether it’s 720x486 or 720x480. Ideally, the resulting image should have a slight padding on the left and right, which then can optionally be cropped to 4/3 (1.33).

The issue is not Topaz . the issue is your original video resolution is not Square Pixel (PAR: 1x1) and you are trying to upscale to a resolution that is meant for Square Pixel size (e.g. 1920x1080). That is why you are getting a strange DAR values (0.89:1). perfect PAR of 1x1 for 720 Width, is 720x540 (for 4:3)

Either you need to select Square Pixel Type in Topaz (not Original Pixel Type), then output to whatever resolution you want.

Or if you want to use original Pixel Type, you should select a custom Width you want, letting Topaz autofill the Height resolution for you… (or select custom Height, letting TVAI autofill width)

P.S. I have noticed personally that “Original Pixel” settings in TVAI generates sharper and slightly more detailed/quality results then selecting “Square Pixel” on my 1998 Video8 4:3 576i camcorder movies. So I never use the “Square Pixel Type” option in TVAI. I always select Original Pixel type.
Either I select custom resolution (as I explained above) or I convert my video to Square Pixel (PAR: 1x1)(prefered way now days for me) 1st using the “Hybrid” Free tool, then process the converted video in TVAI for upscaling.

You can test both for yourself and preview both on TVAI and if you wish you could also use a compare tool to check the results to see for yourself if you notice any difference between the two (that would save you tons of time). or just playback the 2s / 5s preview you generate from both one right after the other to see if you spot any difference in quality.


You’re right that the PAR of NTSC is not square. But Topaz is using the incorrect conversion to square pixel. The PAR of NTSC is 10/11, not 0.89. I am selecting square pixel in the software. Apparently, it’s common in a lot of software because engineers assume the entire resolution (720x486 or 720x480) was used for final 4x3 display, which is not true.

I tried both Original Pixel Type and Square Pixel and got the same aspect ratio. It ends up being a little too narrow. It’s not that it’s not doing a PAR conversion, or else the picture would be a lot wider, it’s using the wrong conversion. Aside from that, Square Pixel did achieve cleaner lines when I compared the two, at least looking at color bars.

PAL 4x3 PAR is 59/54, so ideally after conversion to square pixel, it rounds to 788x576 (production aperture and BBC spec). If displayed on a 4x3 monitor or pillarbox, the left and right edges get cut off and become a perfect 4x3 at 768x576 (clean aperture).

share a short clip of your original video (not the processed one). I will check it out and let you know the results. I have hours of experience in that area with Topaz.

I can’t share client material, but it looks like Topaz is reading something out of the metadata regardless of the source file resolution being 720x486. Attached is how the Topaz menu looks when I load two different 720x486. Both should be the 0.909:1 SAR, but one incorrectly reads as 0.89:1 SAR.


Total understandable you can’t share, that’s fine.
What I would ask you to do, could you load those two supposably identical files into Avinaptic2 tool?

  1. Original Video(s)
  2. TVAI processed video(s) of the same original of course (2 readings per video - Before/After - total of 4 readings)

That tool is a robust tool that provides you the info of the file with all the PAR/DAR,FAR, etc. (much more Info then MediaInfo) and tell me what are the readings?
That way we can determine rather it is TVAI faulty readings or the files are actually different, even though the resolution is identical.
That way we can better understand if TVAI is the cause or rather the victim.

Example: (Before - Original Video)

Example: (After - TVAI upscaled video)

As you can see in my example, TVAI did not alter the Pixel Aspect Ratio (PAR) after upscaling, PAR remained the same. It played around with the DAR to try and compensate the video proportain due to totally out of band resolution conversion (4:3 native resolution → 16:9 native resolution) .

BTW - if you use Crop to fill instead of letterbox/PillarBox, what do you get after upscaling? does it render it in the correct proportions? leave aside for a moment if it crops a bit the image from the bottom/top/side.


Thanks for the Avinaptic2 suggestion. The original file was from a Telestream tape capture. Here’s what I see:

Original mov
Codec: apch
Resolution: 720x486
Frame aspect ratio: 40:27 = 1.481
Pixel aspect ratio: 8:9 = 0.889
Display aspect ratio: 320:243 = 1.317
Framerate: 29.97 fps

Topaz Uprez
Codec: arch
Resolution: 1920x1080
Frame aspect ratio: 16:9 = 1.778
Pixel aspect ratio: 1:1 = 1
Display aspect ratio: 16:9 = 1.778
Framerate: 29.97 fps

I haven’t tried the crop option yet.

What about the other video? the specs for them… remember you presented that two videos with the same resolution are read in TVAI with different SAR. can you post the other one as well? (SAR 0.91:1)

In your current video you can see it is not exactly 4:3. 4:3 the DAR is 1.333 , yours is 1.317 and it is not Square Pixel of course (rectangular - Height greater than width).
besides posting the other video specs I asked above, try to set manual resolution of 1440x1080 and select Square Pixel, I think this will solve your issue.

The metadata in my source is wrong. The real PAR is 10/11, as is all NTSC broadcast footage. It has to be ignored. I find metadata is not to be trusted. It’s often incorrect. I find if a source video is 720x486, it’s going to be NTSC no matter what the metadata says.

Here’s the other video I tested with which upconverted correctly in Topaz. It’s just NTSC color bars generated in Resolve. AVInaptic reports it as PAR 1:1, which is incorrect. Apple Quicktime, however, assumes correctly the PAR is 10/11 and automatically does the PAR conversion to square pixel for display.

Screenshot 2023-05-02 at 8.18.17 AM

I also had those type of issues in the past with SD incorrectly upscaled. the mitigation I found that always works for me is to convert my video to PAR: 1x1 in “Hybrid” (usually i de-interlace it at the same go)
Check that post and scroll to the part I talk about converting in Hybrid, it’s very simple.
your problems would be behind you with this approach.

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.