User avatar
fxgogo
Twickenham , U.K.

Posted Thu Aug 05, 2021 11:47 pm

Well even the design and animation industry got it wrong for many years. In D1 PAL, they were calculating the PAR with out considering the extra raster width that exists in the digital realm. Even when they did notice it, it took Adobe years to update After Effects.

I also find the internet sometimes is a bit of an echo chamber with the same type of mis information or lack of information being repeated over and over.

User avatar
iljitsch

Posted Fri Aug 06, 2021 12:03 am

Extra raster width?

User avatar
fxgogo
Twickenham , U.K.

Posted Fri Aug 06, 2021 4:55 pm

Yeah, so for years everyone was calculating the square pixel screen size as 768 x 576 which would then match the non-square pixel format of 720 x 576. Some bright spark in the broadcast industry realised that digital SD actually has a bigger raster display to that of analog SD and there was an error occurring in some calculations. You can see this effect with the small vertical black bars to the left and right of the picture.

These black bars are only a few pixels wide, but were not being included in the calculation when going from non-square to square pixels. The corrected result ended up as 788 x 576 for a digital square pixel screen size.

But it took Adobe and other creative products a few years to update their presets. I learnt all this from a technical paper that the BBC put out in the early naughties. Not sure if it originated elsewhere first.

User avatar
intric8
Seattle, WA, USA

Posted Fri Aug 06, 2021 7:39 pm

My Beavis and Butthead is showing. I love how you said this:
early naughties.

User avatar
feos

Posted Fri Mar 08, 2024 2:28 pm

nonarkitten wrote:
Tue Aug 03, 2021 6:28 am
The original Amiga hardware documentation states 44/52 for NTSC and 44/44 for PAL, which is factually and demonstratively wrong. In reality, PAL was between 1.041 and 1.067 (~1.05) pixels wide for each scanline and NTSC was 0.833 to 0.86 (~0.85) pixels wide per scanline.
Hi. I'm trying to figure out how to properly encode Amiga emulator footage so it has correct PAR, and I'd like to know where all this info can be read. Both official specs about NTSC/PAL pixel clock and how they can... vary? I can see how different TVs can be configured differently by the manufacturer, but how is it possible for pixel clock to be slightly different? Maybe different per Amiga model?





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