[GEM-dev] interlaced output from Gem?
cyrille henry
cyrille.henry at la-kitchen.fr
Wed Mar 12 12:26:11 CET 2008
Claude Heiland-Allen a écrit :
> Hi all,
>
> Does Gem (or OpenGL in general) have any support for interlaced output?
> The extra temporal resolution would be nice when rendering for display
> on a TV, as the spatial resolution would suck anyway.
>
I think rendering at 50fps on the TV out should do that.
if you want to make a DVD, the best is probably to have a 50fps movie. then, you should be able to downgrade the quality to 25i with a good DVD authoring software.
cyrille
>
> Here's an IRC log from #dataflow :
>
> 09:56 < ClaudiusMaximus> anyone got any tips for generating interlaced
> video in Gem? i think i need to set the gemwin to 2x the framerate and
> 1/2x the vertical resolution, and do some small vertical translations
> up/down depending on which field is the current one
> 09:56 < ClaudiusMaximus> it's the last step that i'm not sure exactly
> how to do
> 09:57 < ClaudiusMaximus> rather i know how, but just not what values i
> should put in..
> 10:29 < rdz> ClaudiusMaximus, i once thought about the same..
> 10:29 < rdz> ClaudiusMaximus, actually it would suffice to have only
> half of the vertical resolution (the scan lines)
> 10:30 < ClaudiusMaximus> rdz: i'm not sure, because the different fields
> are displayed at slightly different vertical positions..
> 10:30 < rdz> ClaudiusMaximus, yeah exactly..
> 10:30 < rdz> ClaudiusMaximus, this could be accomplished by shifting
> half a line
> 10:32 < ClaudiusMaximus> rdz: what about OpenGL line widths being
> measured in pixels? wouldn't that cause problems like "fat horizontal
> lines"?
> 10:35 < rdz> ClaudiusMaximus, sorry.. i didn't understandyour last line
> 10:35 < rdz> what do you mean by fat lines?
> 10:36 < ClaudiusMaximus> rdz: well, if you do "draw line, width 1" you
> get a 1pixel line, right
> 10:36 < rdz> yeah
> 10:36 < rdz> understood
> 10:36 < ClaudiusMaximus> and 1pixel at half the vertical resolution is
> 2x as fat as 1pixel at the full horizontal resolution
> 10:36 < rdz> hm...
> 10:36 < rdz> yo........
> 10:36 < rdz> seems like there should be native support for that in
> gem/openGL
> 10:38 < ClaudiusMaximus> i'm currently leaning towards rendering 720x576
> @ 50fps and using a field-aware downscaler
> 10:39 < ClaudiusMaximus> especially as i want to blur everything
> slightly to avoid horrible compression artifacts
> 10:39 * ClaudiusMaximus been reading this page
> http://www.adamwilt.com/Tidbits.html#CGs
> 10:40 < rdz> ClaudiusMaximus, are you producing for tv ? ;-)
> 10:40 < ClaudiusMaximus> rdz: well, i want to make any dvds i produce
> look better than they do currently...
> 10:40 < rdz> ClaudiusMaximus, i see
> 10:40 < ClaudiusMaximus> rdz: so that's a sorta-yes ;)
> 10:40 < rdz> ClaudiusMaximus, have you already asked gem-dev about it?
> 10:41 < rdz> ClaudiusMaximus, interlaced 3d renderings....... sounds
> very promising...
> 10:41 < rdz> i'd love to see a way to be able to do that
> 10:41 < ClaudiusMaximus> rdz: not yet, will post something today I think
>
>
> Thanks,
>
>
> Claude
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