Did a new test today.
PAL 16:9 Comp and rendered as Animation codec reads 1050x576 in QT Pro and showing correct aspect ratio (wide player window)
FullHD comp and rendered stretched as Animation codec reads 1024x576 in QT Pro and showing correct aspect ratio (wide player window)
FullHD comp and rendered stretched as ProRes Codec reads 1000x576 in QT Pro and showing wrong aspect ratio (compressed player window)
If you're talking standard-definition PAL, you got it right the first time. Don't judge the video by the quicktime player. It's notorious for inaccuracy. For example, you may notice that the frame rate is wrong... but you know that it's right.
Thanks for the input, and you are right concerning the frame rate, but it is obvious that the spot will not pass the technical specifications of the online software with these wrong numbers.
Only the ANIMATION Codec export version showing the right size of 1024x576 was accepted.....so what?
Don't resize the output but instead drop your full HD comp in a standard PAL widescreen comp, fit the HD comp horizontally and then render the new comp without using any resize controls.
Second option, Render your full HD comp to a frame based production master codec (prorez) and then use the Adobe Media Encoder and setup a PAL Widescreen Square Pixel preset. Here's my Pal Widescreen Prorez 422 HQ preset. It is what I use for all requests for Pal ProRez from my clients.