HD to SD Downconversion

[Mitchell Lewis]

As I have Apple Compressor in my arsenal of applications, I think this would be my best choice for testing. There's been a lot of tutorials about using it to make the best quality DVD's, but I don't remember any of them talking about quality scaling.

But your right Perrone, testing and more testing is the answer. Thanks guys! (I can't wait to get our new gear)

[Perrone Ford]

Originally Posted by Bill Ravens

For my money, Cineform is the most stable, both in quality and color rendition, followed by SHEER.

I have used Vegas, extensively in the past. Vegas seems to have a real bone with Quicktime. If using QT within vegas works for you, I'm, honestly, quite amazed.

You don't know how I wish my Cineform would work with the 64bit Vegas. But I have to drop EVERYTHING into 32 bit 8.0c to use it. 8.1 won't read or write to it.

I work in 32bit float in Vegas. I know most people won't because it's "slow". But I find that when I work in 32bit float, my colors, scopes, and everything else works the way I expect. When I take my project out to a different app like virtualdub, the 24bit colors stay true. And I can drop it right back into Vegas with the expected results. This is only for .AVI files mind you.

When I work with Quicktime in 32bit float, everything just works. My renders are on the money, colors are right, and I have no problems. But yes, there is a time penalty. So it comes down to whether you are in a hurry, or whether you want it right. In my case, accuracy is more important, so I do it this way. For someone trying to render video of their kids running around, it doesn't matter. When I have people on the hook for a couple grand, I want to give them the best quality I can.

[Bill Ravens]

ahhh...IC thanx

[Dominik Seibold]

Originally Posted by Perrone Ford

Follow the workflow I gave. Scale the video BEFORE bringing it into the NLE and you'll have no problems. This way, you can edit, grade, etc., on the SD version and deliver it.

I don't see any problems with editing in HD.
Also editing in SD is not a good idea if you want the highest quality.
Grading is destructive in many ways (quantization, smoothness of edges). Text-renders of NLEs often don't have highest quality anti-aliasing. So doing those things will always result in worse quality than the chosen editing-format could offer. So there's truly a advantage of having a HD-pixel-headroom (= super-sampling) while doing those things regarding the final SD-output-quality.

[Perrone Ford]

Originally Posted by Dominik Seibold

So there's truly a advantage of having a HD-pixel-headroom (= super-sampling) while doing those things regarding the final SD-output-quality.

And as mentioned, those advantages are often lost when scaling down AFTER graphics have been added. Cutting in SD has nothing to do with rendering. So cut, grade, etc. in SD sizes (use an uncompressed codec) and before rendering, do a media replacement. I've talked about that here a number of times. It's so simple and the quality is just the same as if you did all the work on HD in the first place.

[Dominik Seibold]

Originally Posted by Perrone Ford

, those advantages are often lost when scaling down AFTER graphics have been added.

Could you explain?

You've said to do video-replacement ONLY if you need HD-output:

Originally Posted by Perrone Ford

And should you need an HD version later, you can simply do a "replace video" from the timeline(...)

which differs from saying to do video-replacement ALWAYS before rendering:

Originally Posted by Perrone Ford

So cut, grade, etc. in SD sizes (use an uncompressed codec) and before rendering, do a media replacement.

[Perrone Ford]

Originally Posted by Dominik Seibold

Could you explain?

Yes, as Mitchell noted, when working with HD footage, and laying in text and titles and rendering to HD things look great. Taking that and rescaling it down to SD causes issues with aliasing and so forth. Or at least it can.

Originally Posted by Dominik Seibold

You've said to do video-replacement ONLY if you need HD-output:

In this thread that's true. However, I've not found it necessary to media replace if simply delivering an SD. If someone else does, then the option is always available.

Originally Posted by Dominik Seibold

which differs from saying to do video-replacement ALWAYS before rendering:

True.

[Dominik Seibold]

Originally Posted by Perrone Ford

Yes, as Mitchell noted, when working with HD footage, and laying in text and titles and rendering to HD things look great. Taking that and rescaling it down to SD causes issues with aliasing and so forth. Or at least it can.

Great aliasing-free rescalers are available even as free software. Why not use them?

[Perrone Ford]

There are lots of ways to get it done. You pay your money, and you take your choice! :)