On Tue, Feb 08, 2005 at 04:27:08PM +0000, John Gay wrote: > Well, I finally figured out how to get POV-Ray to output non-3:4 > ratio frames, so I'm playing around with using Wide screen setting. > > For extra resolution, I'm generating 16:9 frames at 2048 X 1152 for > scaling down. The default output setting is: > PNG image data, 2048 x 1152, 8-bit/color RGB, non-interlaced.
I was going to ask why you wanted to generate perfect noise-free images and then proceed to add noise (scalers always add some "noise") before sending them off to encoding. But you answered that below in your reply, so I'll address it more there. > Time not being a factor, I prefer max quality, would yuvscaler or > y4mscaler be best for this job? I'd like to keep the maximum image > quality right upto the mpeg encoding stage. Why kind of post pov-ray processing are you anticipating? If you really want max quality, you'll get that by doing as little as possible to the pov-ray output images before feeding them into the mpeg encoder. Not to mention that noise free, crystal clear pov-ray images are just the types of images that best fit mpeg2 motion compensation. I am assuming here that you are rendering a pov-ray movie (with motion) and not just a still sequence. On Tue, Feb 08, 2005 at 11:18:05PM +0000, John Gay wrote: > On Tuesday 08 February 2005 21:00, Roine Gustafsson wrote: > > On Tuesday, Feb 8, 2005, at 17:27 Europe/Stockholm, John Gay wrote: > > > I'm also thinking about trying 4196 X 2304 frames to scale down to > > > 1024 X 576. > > > > That is actually not the best way. Render in the final resolution > > and let the renderer do the subsampling is always best. It can > > also be very much faster, since the renderer can optimize the > > subsampling. > > > But the renderer still produces whole pixels, which I can see in > the frames and the mpeg output. even using AA without jitter. I was > hoping the scaler could fix this. But you said above that you wanted max quality. Technically, that is "max" quality. Pov-ray created a pixel, the mpeg encoder faithfully reproduced that pixel. But I think you are trying to fix problem A by applying a solution for problem B. I surmise that what you are finding is that pov-ray is too perfect, in that non-horizontal/vertical lines show pixel stair-stepping. In which case, instead of trying to utilize a possible side effect of a tool that was never intended to to do the job you are looking for, you should be investigating ways to convince pov-ray to output the images in the form you want. If you want smooth lines, try to find a way to have pov-ray do the edge smoothing for you. Or investigate other tools that will take a set of super sharp computer generated images and apply a smoothing to them. Because if you depend on a side effect of the scaler, you may find that if the scaler algorithms change a few months from now, that your side effect you depend upon disappears in the process. > > > I still need to work on my modelling, but there are plenty of > > > POV-Ray models on the Internet if you know where to look. Any > > > other comments/suggestions about rendering images for wide > > > screen DVD resolution would be good on this thread. > > > > Remember to think about non 1:1 pixel aspect ratios, and plan for > > interlacing. Also remember some RGB colors are invalid Y'CbCr so > > preview your test renderings in Y'CbCr before the final render. > > > I know. POV-Ray creates 1:1 pixels. the scaler should convert these > to the proper aspect for wide screen. POV-Ray can also generate > interlaced frames. Maybe you should consider suggesting to the pov-ray development team the possibility of modifying pov-ray to generate non-square pixels. If they are already allowing the generation of interlaced frames, they are trying to be somewhat aware of "video" usages for pov-ray models. Well, in order to properly be "video" usable, non-square pixels are also a requirement. You will get your best quality if pov-ray directly generates non-square pixels than by any post-processing to convert square pixels into non-square pixels. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
