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View Full Version : Please Clarify Image Size and Digital to Analogue


BUZZFX
04-08-2006, 10:35 PM
I thought it would be quite easy to render an image in my 3D application and then import it into IMovie and finally export the movie as a Quicktime file, but it is turning into a mind boggling feat of numbers, pixel sizes and Video formats etc.

What I have learnt is that if I render a 3D or Photoshop image that this image is a digital image and has "Square" pixels whereas an image on the television is an analogue format and has rectangular pixels. So one needs to convert the digital image with square pixels so it will fit on the television which uses rectangular pixels.

If that's not enough, I then have to do a calculation so iMovie won't create two black bars down the sides of the movie. Then I have to make sure I use the right video format. Pal, NTSC DV, DVPRO, NTSC PRO DV and the list goes on.

My question is for those of you who have successfully found a way to figure this all out. Is there light at the end of the tunnel? Are there a few simple steps to figuring out my image size, export size etc.

I want to render a large file in my 3D app., then import it into iMovie, then export my Quicktime movie at a size of 480 x 270. (16:9 aspect ratio)

Please have a look at the link and tell me if you have found a simpler way to understand this and do this. I am NOT getting this. Why is it so difficult?

http://www3.telus.net/~jessum/PAGES/imoviequestion02.html

Integrity
04-09-2006, 05:11 AM
There is definitely a light at the end of the tunnel.

What are you planning on doing with your final Quicktime file?

If your putting it on the Internet or something else that doesn't deal with television or DVD you shouldn't have to worry about all the non-square pixel stuff. Just render it out at 480x270 or higher, and edit it with iMovie using square pixels if it lets you (I've never used iMovie so I don't know what it lets you do).

If you are eventually putting it out on television or DVD or something that deals with the NTSC standard (since I see that you're in Canada), then you should render out at the resolution of DV which is 720x480 with a pixel ratio of 1.2. But I suggest you render in square pixels at 853x480 or something higher then let iMovie do the ratio work.

All of this, again, depends on where you're going with your movie.

BUZZFX
04-10-2006, 04:22 PM
There is definitely a light at the end of the tunnel.

What are you planning on doing with your final Quicktime file?

If your putting it on the Internet or something else that doesn't deal with television or DVD you shouldn't have to worry about all the non-square pixel stuff. Just render it out at 480x270 or higher, and edit it with iMovie using square pixels if it lets you (I've never used iMovie so I don't know what it lets you do).

If you are eventually putting it out on television or DVD or something that deals with the NTSC standard (since I see that you're in Canada), then you should render out at the resolution of DV which is 720x480 with a pixel ratio of 1.2. But I suggest you render in square pixels at 853x480 or something higher then let iMovie do the ratio work.

All of this, again, depends on where you're going with your movie.

Integrity,

Thanks for the reply. I want to render it for the internet and for television. iMovie has a nasty habit of scaling the image so bleck bars appera on both sides of the image when using the Ken Burns effect so this is a problem if I don't have the exact right image size.

You said I need the NTSC standard since I live in Canada. Why does this make a difference?

Finally, shouldn't I render the image at a larger resolution than 853 x 480 for better quality?

Finally, What do you use ofr Editing? I just bought iMovie, but would Finall Cut Express or Finall Cut Pro be easier to use as far as what size of images to use?

scrimski
04-10-2006, 04:52 PM
You said I need the NTSC standard since I live in Canada. Why does this make a difference?

NTSC has a size and framerate different to PAL. Playing a PAL video(which has 25 fps) on NTSC would cause running the video to fast, because NTSC plays more frames per second.
The resolution is different, PAL has 720*576 nonsquare pixels, NTSC 720*540(I could be wrong, siincde I don't use NTSC, it's the measures from one of the AfterEffects presets)

BUZZFX
04-10-2006, 05:13 PM
NTSC has a size and framerate different to PAL. Playing a PAL video(which has 25 fps) on NTSC would cause running the video to fast, because NTSC plays more frames per second.
The resolution is different, PAL has 720*576 nonsquare pixels, NTSC 720*540(I could be wrong, siincde I don't use NTSC, it's the measures from one of the AfterEffects presets)

Why isn't there a universal standard of fps and DV fomat. Wouldn't this make all this a lot easier?

scrimski
04-10-2006, 05:27 PM
Sure it would.
It has more historical reasons: Wernher von Braun used the frequency of the german electricity net for the timing of the fields(50 Hertz=50 fields=25 frames per second) since it was the most stable and broadly available source for precise timing in Germany in the 1930s - at least this is what I was told in school. Since the US and Canada have a different electricity frequnecy, the value for the framerate differs.
There are some more differences in PAL and NTSC than framerate and size, mainly regarding the transmission of color and reference signals.
Of course it would be possible to create one standard, but it's kind of a monkey business. Who will develop this standard and why other companies should use this standard. The actual standard doesn't have to be the best available either. It was the same with VHS and Betamax, now we have this nonsens with different DVD formats. It's about money, not logic.
And this would mean that everybody would have to buy new hardware, software and equipment. Even the actual RGB television is based on a system 50 years old, just to assure that people only using a b/w telly could watch the program, although technically a better quality is possible for a long time.

Tagger
04-10-2006, 06:17 PM
the fact that the framedifference will be around for a while is proven yet again by the comming of HD. While there are no technological needs to make two different standards they made both a 50 and 60 field norm for it. Simply because if they wouldnt have done it, every broadcastingcompany in europe would simply face bancrupcy when they want to change to HD since their entire net is genlocked on 50 Hz and in their perspective it's "a lot easyer" to just leave things like they are. :)

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