square pixels vs .9 for dual output??

[illusory]

I'm about to render a whole lot of pieces of animation, which are destined for 2 formats -- computer display AND DVD. I need square pixels for the computer display and .9 for DVD. They will be composited in DFX+.

What is the best way to render these? I will do them at 720x480, so the resolution will work for both. But, should I output in square pixels? Can this be transformed in DFX+ properly so that it will look right on dvd? Or should I go the opposite way around, and render out at .9, fixing that in post to square pixels?

Please help!
thanks,
NJ

[iconoclasty]

If both formats are 720x480 then it shouldn't matter what aspect the pixels are first. I'm not familiar with DFX but you shouldn't have any problem switching back and forth.

[bob anderson]

Render out in rectangular (.9) pixel aspect. Render as a sequence. Load the sequence in the background (compositing tab) and re-render with square pixels. This re-rendering requires no anit-aliasing etc, and takes under a second a frame.

[illusory]

can I do that the opposite way? Is there a quality loss?

thanks,
NJ

[iconoclasty]

I assumed you were rerendering for square pixels in your 2d software (DFX) Should be considerably quicker.

[Mylenium]

If both formats are 720x480 then it shouldn't matter what aspect the pixels are first. I'm not familiar with DFX but you shouldn't have any problem switching back and forth.

Na, not. The proper thing to do would be to render at square pixels but with 768x504 pixels (which is the proper equivalent of a 720x486/480 NTSC framesize with 0.9 ratio). That resolution can be brought into any compositing and editing program and with proper import/ interpretation settings will be treated correctly, so that when put inside a 720x480 comp it wil have the right pixel sampling. You don't get that if you render 720x480 with square pixels. The pixels will be squeezed the wrong way and lead to prolonged heads, stretched type and all those ugly side effects that we so want to avoid. The same is true when you work the other way around - you can render to 720x480 with 0.9 ratio, but need to make sure you "blow it up" to the correct square ratio for video clips palyed on the computer. If it's going to DVD on both systems, then always render 720x480. All DVD player programs will correct the pixel aspect ratio in realtime during playback.

Mylenium

[illusory]

This is very helpful, thanks!