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pixel aspect ratio problem (i think) - HD to DV

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Chris Pettit
pixel aspect ratio problem (i think) - HD to DV
on Jan 15, 2008 at 11:17:05 pm

Hello.

I have a peice of HD content that my client now wants on DVCAM. I imported the uncompressed content (1280x720) into a DV NTSC composition.

No matter what I try, the output looks terrible on an NTSC monitor, jagged and aliased all over the place. I've tryed everything, outputing from Premiere, Final Cut on my Mac, and of course my prefered option, from AE, same results.

I've read lots of posts that relate generally to this topic but I don't see anything that specifically addresses this issue.

Is this problem related to the pixel aspect ratio? If so, how do I best convert from HD 720P square to DV/NTSC .9?

Thanks in advance

C


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Thom Obarski
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 12:32:16 am

The best way we handle this at our shop is to set up a timeline that is already in NTSC DV format (720x480, DV/DVCPRO NTSC pixel aspect, etc) render this then output as quicktime with "Current Settings" enabled.

Hope this helps!
~Thom

"This is post, you can't fix it after this."


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Chris Pettit
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 12:50:40 am

sorry, I, m not sure what you mean.

I created a new DV NTSC comp and then imported and "fit to comp" the source HD content, and it looked horrible. Is there something else you are recommending?

I did find some info since my post concerning a 720 x534 comp that is then dropped in a 720x480 DV comp to compensate for the tweaked pixel aspect ratio issues... Anyone heard of that fix?

Thanks!

C



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Darby Edelen
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 1:47:31 am

[Chris Pettit] "I created a new DV NTSC comp and then imported and "fit to comp" the source HD content, and it looked horrible."

1280x720 HD footage is 16:9 so I would recommend using a DV NTSC Widescreen comp and using 'fit to comp' on the footage. It doesn't change the actual pixels, but things will have the correct proportion on screen. If you want to see the actual pixels in your footage, disable pixel aspect ratio preview (this will eliminate the vertical lines that are digitally introduced during preview when you have pixel aspect ratio preview on).

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA


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Chris Pettit
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 2:24:34 am

I'm sorry, I haven't been descriptive enough.

I am aware of the "screen" aspect ratio issues between 4:3 and 16:9. I have both expanded my 16x9 content so that it filled a 4:3 screen and shrank my content down so that it achieved letterbox form, both are options for this project. Not a problem. I also rendered out to 16x9 anamorphic as well.

The problem relates to the poor quality of the PIXEL aspect ratio conversion. No matter how I fit the square pixel content into a NON-sqaure pixel comp the results on an NTSC monitor are horrible. (the same content on the desktop looks fine unless I click the AE "toggle aspect ratio" button I'm talking about stair-stepping and "jaggy" edges etc AFTER rendering to the DV codec.... not simple aspect ratio problems

I have heard similar complaints from editors (I'm more of an animator)

Red Giants' "Instant HD" seems to offer a software solution for the opposite direction, ie from DV to HD. And for similar reasons, but I don't see any info on stepping down from HD to DV

Thanks

C





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Darby Edelen
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 4:42:51 am

So what it sounds like you're saying is that the footage looks perfect at every stage until you look at it on an NTSC monitor? How are you viewing it on the monitor?

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA


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Chris Pettit
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 1:27:00 pm

Via firewire. Firewire to DVCAM deck, SVIDEO out to SONY monitor



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Steve Roberts
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 3:54:08 pm

Just confirming. Have you tried this?

- import HD footage into AE
- interpret as 1280x720, square pixels (if AE didn't do it automatically)
- create DV (0.9) comp
- drag footage into comp
- fit-to-width (cmd-opt-shift-H) for letterbox, or
- fit-to-height (cmd-opt-shift-G?) for pan/scan

If it still looks bad ... how does native DV footage look like in the same comp, same pipeline out?
Have you tried making your own 1280x720 graphic and putting it through the same workflow?



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Chris Pettit
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 4:19:38 pm

Thanks, I did do those things, basically went through each step, with bad results.

I have discovered a couple of things since my last post however that I thought I would post in case anyone else made the mistake I may have made:

The material I am working on is 3D content entirely generated from C4D. When I try dropping generic HD 720P footage into this process, it looks just fine (or as fine as DVCAM can) So there may be something about the footage itself, its highly detailed and I am used to looking at it clean, by comparison the 5to1 compression of DV looks bad natively.

Also, this may be where I went wrong: I assumed that when you import square pixel content into AE DV comp that you need to re-interperate the footage to NTSC DV(.9), and I think that is what I did. When I made sure the footage was left square, even though it is going into a NON-sqaure comp I got much better results. I'm still confused by that, but that appears to be the most likely culprit.

And lastly, I got much better results when I went with widescreen instead of letterbox. That was mentioned in a previous post, but my client said they needed 4:3. I have now talked them in to widescreen.

So I appear to have a solution, I can't thank all those who helped me think through this enough!

C



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Steve Roberts
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 4:26:58 pm

Yes yes yes. Unless you really know what you're doing, you should interpret footage as "what it is". If it's square pixel footage, interpret it that way, or let AE do it.

When you drop something into a comp, AE automtaically adjusts it to fit the new PAR, so don't go back and misinterpret it.



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Chris Pettit
Re: pixel aspect ratio problem (i think) - HD to DV
on Jan 16, 2008 at 4:31:40 pm

Thats it then! total confimation of what I did wrong. Fantastic, thanks again!



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