View Full Version : HDV to SD production - How?


Steve Reid
October 19th, 2005, 06:02 AM
Hi everyone. First post here so hoping that a few knowledgeable souls can help!
Using an Sony Z1 I have shot in HDV 1080i for a production that is to be final output of on DVD SD 576i PAL.
We will be mixing/cutting with CG rendered animations outputted at 576i.
We need to be able to do post in (PC platform) premier and combustion then corrected footage will be passed to a FCP editor to compile/edit scenes for final DVD.

We are now foreseeing problems downconverting the HD footage. I am a photographer more than a video editor so need help to understand the process.
Firstly I captured the mpeg2 stream via CapDVHS and it looks great, more like digi beta quality. But how do I (down)convert this in to a true editable lossless format and resize to 576i.
Also I believe there may be problems with the interlacing differences of HD and SD. Does HDV footage need to converted to an editable format and deinterlaced first then resized and re-interlaced to match 576i interlacing.
If so the interlacing will be fake and not real with lens captured time difference in each field?
Can this be done in one 'move', also I have read that the ZI can choose to output and downconvert to SD - if so how does this affect picture quality and interlacing motion artefacts?
End of day its for a commercial & domestic dvd presentation/distribution and needs to look good with no motion juddering or over compression effects.
Help would be much appreciated.

Cheers
Steve

Steven White
October 19th, 2005, 11:18 AM
But how do I (down)convert this in to a true editable lossless format and resize to 576i.

All you need is software that will handle the fields properly in the down-conversion. I'm not sure what software you have... if you can post a list of all the tools you've got (Premiere? After Effects? Vegas? FCP? AspectHD? etc.) then someone should be able to come in and give you a workable solution.

Can this be done in one 'move'

Yes. AspectHD does this very well. I think Vegas handles it too, but I'm not sure (Douglas Spotted Eagle is the man for that).

the ZI can choose to output and downconvert to SD - if so how does this affect picture quality and interlacing motion artefacts?

The Z1 will down-convert to the miniDV format. This process is hardly lossless and will affect the image quality with 4:1:1 sampling and DV compression artefacts. It will however handle the interlacing very well.

-Steve

Steve Reid
October 20th, 2005, 04:00 AM
We have Premier Pro, Combustion 4, Vegas(Demo only), Virtual Dub Mod at work-PC platform here, and have I FCP HD on a Mac G5 at home.

I have done some tests on Premier Pro with some success but converted footage now displays motion juddering on shots with traffic, and some darker background trees display mild blocky compression also general edge softness.
- Are these just part of the process that I will have to put up with or will other progs downconvert much better?

Looking on this forum and others it appears that most are only downconverting 108i HDV to a progressive SD production (I assume for a filmic look) and not to 576i- is this right?
How are people then making an interlaced output for DVD viewing on normal TVs etc?

Or am I getting hung-up about the reinterlacing part. I'm sure that deinterlacing then reinterlacing is seriously softening the image quality and messes with natural motion.
Only our animations work much smoother when rendered out with fields as progressive frames display motion juddering artifacts.

If I only Downsize convert and not deinterlace what happens to the HDV fields? Do they turn into DV format or mismatch project output completely?, or is it your editing program that makes or controls the fields and how they look?

Should I just be editing in 25p (PAL) for ease as everyone seems to be doing this and then render out final movie interlaced?
(This would probably work better for my Combustion & greenscreen compositing jobs anyway but our animators are not keen on it.)

Hope my ramble makes sense to some :-)

Thanks
Steve

Steven White
October 20th, 2005, 07:43 AM
Is it Premiere Pro 1.5?

If this is the case and you want painless down-conversion, here's what I suggest:

Go to www.cineform.com and download the demonstration version of AspectHD. Install it, and place your edit into and AspectHD 29.97i timeline.

Simply choose File->Export->Movie, choose 720x576, change the field settings to lower field, and render to uncompressed. Cineform's export module will handle all the fields beautifully, and you'll have a 4:4:4 uncompressed down-converted SD master.

Alternatively, I'm sure you could achieve the results in Combustion by placing the HDV file into a 59.94 fps timeline, and creating a 60p file. Down-sample the 60p file on export to SD, and from there re-combine the fields (lower field first) to acheive 720x576i. This allows you to check the output on each step of the way.

I have done this particular process in After Effects, and it acheives excellent results - so I wouldn't worry too much about softening... it's nothing compared to what you'd get from compressing to DV.

Hope that helps?

-Steve

Steve Crisdale
October 21st, 2005, 03:54 AM
Don't forget that the 30 and 60fps that Steve White was referring to aren't applicable in your case Steve Reid... unless you are shooting 60i on your Z1 - but I'd be wondering why when you're in PAL land!!

If I could further suggest - beyond what Steve W has already mentioned, that you not only get the AspectHD demo, but that you not only edit in the CFHD avi format, but that the final CFHD avi of your project is what you import into your DVD authoring app.

Set your DVD burning app to create PAL WS 16:9, and bit-rate as high as you can get it for DVD. 9.3 is pretty good. The authoring program will then do the resampling, and as long as your DVD settings are right - you should get a pretty good looking end product.

If you attempt to create a MPEG2 from Premiere, just remember to use "Dual-pass" and set bit-rates to be as close to max as possible. If you go variable bit-rate, make sure the average and minimum rates are bumped much higher than default. You may also find motion compensation is viable depending on the video subject.

Good luck!!

Steve Reid
October 21st, 2005, 09:01 AM
Cool, thanks guys, We will have to upgrade our premier pro 1.0 first but Aspect HD with cineform looks like the one as can do both render resample to a mov for FCP or edit natively in premier as an avi/mpeg2.

Thanks I will give these a try.

Also there have been a few debates on to shoot or not to shoot HDV (just stick with SD) - I assume you are both saying that its still worth it to shoot in HDV even for a SD production?

Cheers
Steve.

Steven White
October 21st, 2005, 09:09 AM
*smacks head*

Yeah, I meant 50p there. Sorry 'bout that. At least I got the 576 right! :)

I assume you are both saying that its still worth it to shoot in HDV even for a SD production

If you have the funds to edit HDV (i.e., with AspectHD + PPro 1.5.1), then I suggest you shoot in it, and keep your project HD until the very end. With a properly equiped AspectHD system there's really no benefit whatsoever to down-converting to SD before editing, given the real time performance of the system.

If your plan is to actually edit the whole thing in SD - while I can see a substantial quality increase from shooting HDV first, the workflow will be cumbersome at best... and by the time you have the tools to do the down-convert painlessly, you'll be equipped for real-time HD editing.

-Steve