Rendering resolution


(wbrunk) #1

When rendering a sequence to an AVI raw file, should the “sizex:” and “sizeY:” settings to the right of the “Animation” button be set to 720 and 480 respectively since my AVI file will be downloaded to a DV video tape and played on an NTSC TV ?
Thanks in advance.


(Atomike) #2

Standard tv resolution is 720 x 486. However, if you do the math, you’ll see that this is not 4x3 which is the dimensions of NTSC D1 television (USA). The reason for this is that computer monitors and tv’s use different shaped pixels. TVs use oval pixels, while computer monitors use square ones. I’m not sure how blender is set up (it may ovalize for you, but since it’s not a US product specifically, I doubt it). Therefore, I’d guess you want to export as 720 X 540 (which is 4x3 in dimensions). When the picture is squeezed to the right dimensions on the tv, it should LOOK like what you see on your monitor. That is just a guess based on what I know of US television. A true blender guru may set me straight though.
Atomike


(meestaplu) #3

When I render animations, I render them at NTSC DV resolution - 720 x 480. NTSC D1 is a little bit bigger, at 720 x 486, but getting the aspect ratios right in Blender is a bit of a pain at that resolution.

Here’s how you get 720x480 to come out looking right on your TV. Set AspX to 8 and AspY to 9. If you measure the dotted lines that show the extent of the camera view, you will see that there is a 4:3 aspect ratio. However, your renders will come out looking squished - that’s OK.

Then load your animation into Video Toaster, or VirtualDub, or whatever you use, and play it out to your tape. It will look right on your TV; a TV has rectangular pixels.

Matt


(Atomike) #4

Seems like rendering at 720x540 would do the exact same thing, and could cut out the middle step. I always have our art department give me 720x540 stuff for use on t.v., but, like I say, blender maybe different for some reason and this wouldn’t work, although I can’t imagine why.


(meestaplu) #5

Atomike wrote:

Seems like rendering at 720x540 would do the exact same thing, and could cut out the middle step.

Yes, it would do the exact same thing - and it would work with Blender. However, you render an extra 43,200 pixels (13% more) that will just be thrown out when you convert your video to NTSC DV. That’s roughly a 13% longer render - which is quite a lot for long animations - and also a complete waste of time considering that the data will be thrown out anyway. The 720x540 image is also made up of a series of square pixels, not rectangular ones; that is inconsistent with the final format.

In summary, the 720x480 resolution will give you a faster render, a smaller render (about 100 MB per 30 seconds if you’re doing uncompressed video), and a render that is consistent with the medium that you are using.

I am not so sure about the 720x540; I have run into pretty strange artifacting problems when converting from one resolution to another.

Atomike - what is that middle step you mentioned? I’m not totally clear on that.

</Matt>

EDITED: Now I spelled your name right…oh man. :smiley:


(Atomike) #6

Good explaination presented. The extra step I was referring to was the changing of aspect. I like your reasoning for rendering in 720x480 - sounds solid. If you’re getting weird looking video by rendering at 720 x 540 though, it may be due to the editing program being used. I work in television and we do 720x540 all the time (although that’s importing to high-end AVID systems). Using a home program, your aspect ratio idea is probably a good (or best) solution, although I’ve not tried it.
Atomike


(meestaplu) #7

Atomike wrote:

I work in television and we do 720x540 all the time (although that’s importing to high-end AVID systems). Using a home program, your aspect ratio idea is probably a good (or best) solution […]

Oh, the irony! My 720x480 render was imported into NewTek’s Aura 2 - a video processing program that is integrated into Video Toaster 2 (www.videotoaster.com). I would LOVE to have that at my house…

My artifacting argument was probably invalid, although I did not think about it at the time. Video Toaster does not need to convert video in order to play it out to TV; it will display just about anything. However, it handles NTSC D1, D2 and DV resolutions best - they are the standard. Without conversion, a 640x480 clip looked terrible, but it did play. If I had converted it as you do in AVID with your 720x540 clips, it probably would have looked just fine. I’ll try and see about that on Monday; the Toaster is at my high school where I can’t get to it right now.

EDITED: It seems that I cannot spell your nickname right!


(meestaplu) #8

I didn’t forget about the test I said I would do - but a ton of people have been using the system for much higher-priority projects. Possibly later today I will have the results.