HDV to DV order of rotate and sharpen?

RalphM wrote on 3/23/2009, 10:09 PM
I recorded video of a play on Sunday evening using an HDV cam for a locked down wide shot. I used two SD cams for close-ups. The project will be delivered in SD 16X9.

Unfortunately, the HDV cam was not completely level. I will need to rotate the video a few degrees. It also appears theHDV footage could benefit from a little sharpening.

The video is about 50 minutes in length, so processing times for these two steps in HDV would be very lengthy. If I were to downconvert to SD before rotating and sharpening, would there be a noticable difference vs doing the two steps in HDV before downconverting.

Thanks,
RalphM

Comments

farss wrote on 3/23/2009, 10:37 PM
I'd recommend rotating before downconverting.
Absolutely sharpen after downconverting.

Please, please, pleeeease don't let a render run for days only to discover something is wrong. Test, test, test a minute's worth.

Bob.
Mahesh wrote on 3/24/2009, 3:24 AM
I frequently use a locked of HDV cam with SD. I mix the HD and SD footage on the timeline. Corrections are applied at the event level. Once edit is complete, I select the clip in media pool, right click on the clip, select events on time line and use 'paste attribultes' to apply correction to the events.
RalphM wrote on 3/24/2009, 6:33 AM
Thanks for the replies. As I look further at the HDV footage, I see some areas that I'd like to zoom a bit. I'm assuming the proper order would be rotate, zoom, downconvert and sharpen.

My modest laptop makes it much more feasible to apply corrections to the 50 minute source clip than at the event level. There will be many cuts between the wide angle and the closeups, and I don't think I want to suffer through manipulating HD footage on the timeline. Time for a new editing machine!

Ralph
kairosmatt wrote on 3/24/2009, 12:02 PM
Bob and Ralph-

Why down-convert before sharpening?

Couldn't you just rotate, zoom, sharpen then render to the final product (with the DV already mixed into the timeline)?

kairosmatt
farss wrote on 3/24/2009, 2:53 PM
"Why down-convert before sharpening?"

If you apply sharpening before downconversion you'll increase the risk of aliasing and line twitter.
General recommendation if shooting HD for SD delivery is to even turn off or down Detail in the camera. Then after downconversion apply sharpening. There's no hard and fast rule here though so you need to check results on a CRT. The problem is most noticeable when shooting progressive on the higher end cameras. You can still induce the problem by applying sharpening to any image if you're delivering interlaced footage.
Be aware that almost all SD delivery systems are interlaced.

Bob.
Laurence wrote on 3/25/2009, 6:53 AM
Make sure that if you are working with interlaced footage, that you select a deinterlace method before any kind of resize including the slight zoom you will be doing during this straightening process. Conversely, if you are working with progressive footage, make sure that the "select deinterlace method" tab is unchecked.

Zooming in on interlaced footage without the "select deinterlace method" tab checked will give you all sorts of squiggly edges on any lateral movement. Selecting a deinterlaced method and then zooming in a little on interlaced footage will still give you interlaced footage on the output. The reason you need to do this is because it will force Vegas to separate the even and odd fields, resize them separately, then fold them back together by even and odd lines. I can't stress enough how important this is.

As far as sharpening goes, I always apply a generous amount of sharpening during the actual downrez render. Never before and never after. I don't know why exactly, but in my own personal tests, this is what looks the best. What you need to do is do a couple of tests for yourself. Do sharpening before the downrez. Do it after. Do it during. Play with different amounts. Then do what looks best to your own eyes. The only way to get a feel for this is through experimentation.
RalphM wrote on 3/25/2009, 7:14 AM
Many thanks for the inputs on my questions - some real nuggets to chew on there. I will definitely do some testing before committing my poor laptop to a couple of days of rendering.

Cutting this together is going to be interesting. The venue had two locations for cameras: too close (10 feet from actors) and too far back (50 feet) from stage. Good thing I'm doing this gratis as they could not afford to pay me for the hours this will take!

Ralph
farss wrote on 3/25/2009, 7:18 AM
"Do sharpening before the downrez. Do it after. Do it during."

How do you do it during?

Bob.
Laurence wrote on 3/25/2009, 7:23 AM
I apply it as an effect that I enable just during the downrez render. You can sort of fine tune it by setting your project properties to your target downrez resolution and looking at the preview set to best quality full resolution and apply the sharpening amount until what you see in the preview window looks best. I never really use much sharpening any other time, but during a downrez, I find myself using quite a lot of it. The difference it makes is really stunning.
megabit wrote on 3/25/2009, 7:36 AM
Perhaps this is a dumb question, but let's assume that in order to avoid multiple lossy renders, I'm doing only a single render into SD MPEG2 from my HD stuff. How do you ensure that sharpening is done AFTER downconversion? According to the online help, the PRE/POST toggle only determines whether a given effect is applied prior to, or after pannig/cropping or compositing; I never found downrezzing...

What am I missing?

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farss wrote on 3/25/2009, 2:36 PM
Not a dumb question at all!
I recently wanted to apply a number of FXs before downrezzing and add sharpening after. I was not convinced I had this nailed as flipping the triangle changed the order of the FX chain. I gave up and rendered from 720p to SD YUV and then added the sharpenning to that and rendered to mpeg-2.
Nesting should be the surefire way to do this in Vegas, precomps in AE is another common mechanism to ensure things get done in a defined order. I wouldn't sweat too much over generational loss, there's no need to use lossy codecs these days.

Bob.
sdorshan wrote on 3/29/2009, 2:29 PM
Along the lines of converting HDV to DV, because of the enhanced resolution of HDV over DV, I want to fake zoom by cropping the HD video. I figured that there would still be enough resolution to look good in DV (720x480 Widescreen), but it just doesn't look very crisp when cropped.

What is the best size to crop to in order to zoom in on HDV (1440x1080 from a Canon HV30) and get a decent picture?

I've tried cropping to 720x540, or 640x480. I assume that 720x480 doesn't work because the HDV pixels are 1.33 width, and the DV pixels are 1.21.

I have the project set to NTSC DV Widescreen. Is that correct, or should I be editing an HDV project, and then rendering to SD? The HDV aspect ratio doesn't quite fit the NTSC frame, so I'd have to do a little cropping, wouldn't I?

Thanks,
Scott
farss wrote on 3/29/2009, 2:43 PM
"....but it just doesn't look very crisp when cropped."

You could try adding a little sharpening to it.
Just because the image was recorded in HDV doesn't mean it's High Definition though. It's quite easy with a HDV camera to record an image with lower than SD actual resolution.

Bob.