Still Photo Aspect Ratio Confusion

Question

Apologize for asking a question on this topic as I have been through the forum and realize the topic of aspect ratio comes up often. I have not however seen this question answered. Quick background:
-Working with HD Video footage imported as SD as I am burning non-HD dvd's and I have heard the conversion in IDVD and Toast from HD is not great;
-Using photos imported from Aperture in FCE;
-Sequence is NTSC anamorphic as I want 16:9 but without HD;
My question is about the aspect ratio of still photos when I bring them into the timeline. I have experimented with saving photos in different aspect ratios: 853x480 and 720x480. When I import into FCE the 853 shows a square pixel and the 720 shows a NTSC pixel. From what I have read this is due to the way FCE interprets the aspect ratio and assigns an pixel aspect. When I view each in the viewer they both look correct when I click the corresponding pixel aspect from the top of the viewer. It is when I move these to the timeline that I get confused. The 853 gets an adjustment of 18.52 and the 720 gets an adjustment of 33.33. What do these adjustments actually represent? Is it a percentage, a number of pixels, something else? When I read about it in the Manual it seems to state that FCE adjusts for the difference between the still and sequence, but then why does it adjust the 720 since it has the same pixel aspect as the sequence? I then tried changing the Pixel aspect of the 853 in the browser to NTSC and moving it to the timeline. I get the same 33.33 adjustment. The 33.33 does not look correct in either of them, but when I change it to 18.52 it looks correct (with the pixel aspect at square, with it not checked it looks "skinny" or squished).
Only thing I can think is that it has something to do with the anamorphic adjustment and the squeezing that goes on with it as 18.52 as 853 (widescreen) is 18.47 percent wider the 720.
At this point I am really not sure how these will display when I make a dvd and display on a widescreen tv. I would prefer not to do this by guessing or looking at the picture, but instead by understanding what FCE is doing and making sure I have the settings and adjustments correct.
Sorry for the long message, but would really appreciate any advice

Answer 1

Michael,
sorry to disagree, but for sure I was not clear, and the topic is quite complex. So I decided to provide an overview (as much as I can...) of the various combinations of clips inserted into various sequences with all settings - possibly on my web site (I'm afraid other posters are getting bored about all this math).
But since this is taking quite a bit of time, let me just tell you now where I disagree about your findings. When I'll have my overview completed I hope that will better explain what I mean.
_Your point 1_.
I'm pretty sure you (unwillingly) are importing your 16:9 square pixel NTSC clip into a +4:3 CCIR pixel NTSC sequence+ (not your original 16:9 anamorphic NTSC sequence). Please check your sequence settings by selecting the sequence in the browser in list view and reading the Frame Size, Pixel Aspect, and Anamorphic fields.
a. If your sequence is in fact +4:3 CCIR pixel NTSC sequence+, by applying the formulas you get:
- PARclip for +16:9 square pixel NTSC+ clip = 853/853 = 1 (as for any square pixel clip)
- but PARseq is not 1 (as you write) but 640/720 (square/actual pixels) = 0,8888
- Adjust = PARseq/PARclip = 0,8888/1 = 0,8888.
- Since Adjust is <1 Motion Aspect Ratio = - 100* (1/0,8888 -1) = -12,5 as you experienced on FCE. BTW this means that the imported clip has to be squeezed vertically by 12,5% (as opposite of horizontally).
b. If your sequence instead really is +16:9 anamorphic NTSC+ as you seem to imply, then 18,52 is correct as you confirm yourself with "Agree that in the four cases you list it agrees...": it is in fact the 2nd case in my 4 cases list.
_Your point 2_.
Here I suppose the sequence is +16:9 CCIR pixel NTSC+ which has PARseq = 853/720 = 1,1852.
But I'm not clear what you mean by "720/640 NTSC clip". My guess is that you mean a +4:3 CCIR pixel NTSC+ clip,
then PARclip = 640/720 (square/actual pixels) = 0,8888
then Adjust = PARseq/PARclip = 1,1852/0,8888 = 1,3333 and Motion Aspect Ratio = 100*(1,3333 - 1) = 33,33 as you experienced
_Adjust formula_.
I think this formula in your earlier message is incorrect: Aspect Ratio (in Motion/Distort) = - 100 * (1/Adjust-1) if Adjust ≤ 1; seems like the formula: Aspect Ratio (in Motion/Distort) = 100 * (Adjust-1) if Adjust ≥ 1 works at all times including <1 as follows 100*(.875-1)=-12.5.</div>
This not true (well it is true only for Adjust = 1...). As an example if Adjust = 0,8888 then 100*(0,5-1) = -11,12 (wrong value for this pixel adjustment), while -100*(1/0,8888-1) = -12,51 which is the correct vertical squeeze !!
Why 2 different formulas are needed ? because when Adjust is >1 a +horizontal squeeze+ by Adjust is necessary to fix the pixel aspect ratio misalignement, when Adjust is <1 a +vertical squeeze+ is necessary by 1/Adjust... (figures will help as soon as they are ready for... publishing).
I'm sorry these posts are so long, I try to make them as clear as possible, but the topic is a bit messy and, even if only fractions are involved in this math, their actual meaning is not always intuitive...I'd really appreciate any comment also by more experienced users of FCE/FCP...
Thanks
Piero