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The match doesn't work. If you want to export a 16:9 project to a 4:3 clip I recommend that you import the 16:9 project into a new 4:3 project and export from there.
When I import my 16:9 project into my 4:3 project, is there any quality lost besides the obvious horizontal areas that are cut off?
Is this an HD or SD widescreen project? Are your sources interlaced or progressive?
SD - Interlaced.
You'll need to deinterlace the video before scaling it down and Premiere's built-in deinterlacing is horrendous, so you'll lose something there for sure.
Assuming you're running Windows, consider ouputting the sequence from Premiere as an .avi and using VirtualDub to do the deinterlacing and scaling. You'll also need SmoothDeinterlace or another deinterlacer plugin for VirtualDub (the program and plugins are free, so you've nothing to lose here).
As for the math (assuming this is an NTSC source and 240x180 output):
Scaling Factor = 180 / 480 = .375
NTSC Widescreen aspect ratio = 1.215
720 x 1.215 = 874.8
874.8 * .375 = 328.05
scale to 328x180
crop to 240x180
Deinterlace. Yes. However, there is nothing wrong with doing that as you export.
No. There is no quality loss other than the edges getting cut off. That's it. It's easy, and if you need to pan to the right or left to get the best part of the larger frame into the smaller frame, you can do that with Motion.
Well, Chaunce, there you have it: Two differing viewpoints. Most of the output I do is for 4:3 square-pixel reduced size computer playback. Suffice it to say I have not been entirely satisfied with Premiere's handling of such a seemingly simple task.
Deinterlacing is an inherently lossy process. Even the best deinterlacers can't do it perfectly. So, I certainly cannot say that this is "lossless". Granted, scaling to such a small size as 240x180 will likely hide some of the adverse effects of poor deinterlacing.
I am also not particularly pleased with the way Premiere scales video. Large ratio scaling (like 720x480 -> 240x180) looks way too soft for my taste. Sadly Adobe does not implement better scaling algorithims (such as Lanczos) for resizing. It can really help preserve detail when downscaling video and images.
Premiere (and all the Adobe products) use approximated pixel aspect ratios. You may find that these produce slight stretching or squeezing of your footage when converted. It may not be problematic, but it is not "correct", strictly speaking.
For these reasons, I use Premiere strictly for editing and I have found alternative tools for preparing content for PC playback. I am hoping that Adobe will continue to make improvements in these areas.
Dan & Steve,
Thanks for all of the information as well as both of your opinions.
2 more quick questions:
1. When using a 4:3 project, if I want to make my video say 180 pixels high - what I normally do to figure out the ratio is create a 320 x 240 blank square pixel image in photoshop. Then I change the height of that image to 180 and whatever the width comes out (in this case it came out to 240 x 180) to is what I will resize my flash video to when using the Adobe Media Encoder.
Is this the correct way to do it? I've noticed when I drag the width or height in the Adobe Media Encoder it doesn't keep things in proportion.
2. And one last question on this - if I'm doing the same thing and I drag my flash video size from 320 x 240 to 400 x 240 (just a random width) and render that - am I retaining quality and making a clip that just has too much width with black video or am I "distorting" the new video clip?
Just be careful to make sure that both numbers are evenly divisible by 8, and just about any 4:3 ratio will work for you. The 8 has to do with the way encoders work best.
If you use a random width, you generally be stretching your video out of whack. It depends on how you do it, I suppose.
Does this apply to a 16:9 ratio as well?
>There is no quality loss
Premiere simply throws out one field (half the vertical resolution) when it deinterlaces, creating very noticeable artifacts. There are better ways to do the job.