Why does changing properties Width/Height make HUGE render difference?

clearvu wrote on 7/25/2003, 6:00 AM
I rendered a project at the normal 720x480 and it took 45 minutes. I changed the project properties to 700x480 and it only took 27 minutes. Why such a difference? Is this normal?

Also, what exactly am I doing to the resulting video? Am I screwing up the end result that things will not look right on TV? My reason for changing the setting was to keep the left and right edges from being cut off by TV.

Comments

farss wrote on 7/25/2003, 6:26 AM
Anything that causes VV to have to remap all the pixels in every frame is going to involves a huge number of calculations.
If you have the default of bicubic transformation set then it recalculates a new set of pixels taking into account their neighbours as well. A simple bit of arithmetic shows how large a number of calcs are involved, 720 X 480 X 30 for ever second of video and thats just the number of pixels.

Trying to stop things being cut off from the edge of the TV is a mistake in my opinion. There has been a bit of discussion on this topic some time ago but in summary every TV crops images differently. The correct approach is to ensure that you always shoot with safe areas in mind. Most decent cameras have one or more safe area generators that provide rectangles in the viewfinder to help with this.

If its all too late or it isn't something you've shot anyway and this is a big issue for you I would pan / crop the image to ensure it fits within the safe area on the monitor. Bear in mind though your render times will be long and everytime you zoom into an image you are loosing resolution.

Hope this help.
mikkie wrote on 7/25/2003, 8:05 AM
"I rendered a project at the normal 720x480 and it took 45 minutes. I changed the project properties to 700x480 and it only took 27 minutes. Why such a difference? Is this normal?"

Really don't have enough info to say why one took longer then another, stuff like what was the source file format and size, what did you render it to, what were your proj settings, and so on.

"Also, what exactly am I doing to the resulting video? Am I screwing up the end result that things will not look right on TV? My reason for changing the setting was to keep the left and right edges from being cut off by TV. "

This has been discussed a bit in other threads. Basically, your TV accepts, wants, needs a signal that's wider then the center portion you see. The normal way to deal with it is just that, to learn to deal with it and shoot for the center or "safe" area.

Work-a-rounds include playing the video back to your TV using a TV out or external scan convertor from your PC - that way you can control the size, placement, and often proportions of your video on the TV screen, and you can record it that way to tape (or actually another PC).

Otherwise, while it can be tricky to maintain proportion, you can letterbox your video with the bars on each side. You'd still want the overall size to be 720, with your video centered and sized at something between 640 and 704. This way the black bars on either side will fill out the display, but only in those areas that are hidden.

Assuming your rendered video looks OK, maintains the right proportions, might work to import it into a new project that's set to 720, then set the clip to not fill the screen, and to maintain aspect. Haven't tried it for this purpose, but know doing basically the same thing Vegas will insert the black bars for the more usual top & bottom letterboxing.
SonyDennis wrote on 7/31/2003, 5:14 PM
Unless you're using the "default" template, or a template set to use the project size, this shouldn't have made any difference, as most render tempaltes override the project size settings.
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