1080 or 720 for best SD downconvert? at DVinfo.net

Rob Collins · July 10th, 2008, 10:48 PM

I'm about to do the 48 hour film project, shooting on EX1 / Letus Extreme. The film must be delivered as a 4x3 SD QT file. My plan is to edit FCP in HD / EX native, export, then drop the file into a DV50 timeline (letterboxed), render and export again.

First, does that sound like a good workflow? Even though it's SD delivery for the competition, I want to have it in HD too.

But to the main question: does 720 downconvert better than 1080 or vice versa? I've done a simple test and can't see a difference, but wondering about different shooting situations, etc.

Having slow motion available leads me to want to shoot 720. In my tests, the one thing that DIDN'T look good was a 720 slow motion clip brought into a 1080 sequence then downconverted.

Thanks for any advice.

Bill Ravens · July 11th, 2008, 07:11 AM

IMHO, downconverting interlaced footage to SD looks pretty crappy. It's hard to avoid interlace flicker. Therefore, any de-interlacing you can do before you downconvert, I think, is always helpful. My preference is to work with 720p files.

I would also suggest NOT using any in-camera DETAIL...turn it off in the menu. Camera sharpening makes downconvert much harder and increases flickering on horizontal lines in the footage. If needed, apply post-process sharpening after downconvert.

Rob Collins · July 15th, 2008, 10:47 AM

I've just done some tests and concluded that FCP does a better downconvert than Compressor, and takes less time. Here's two clips you can download, comments welcome:

http://idisk.mac.com/robcollins-Public

I also determined that there was no noticeable (to me at least) difference in downconverting 1080 vs. 720. 30p seems to do a bit better than 24p.

Alister Chapman · July 15th, 2008, 11:23 AM

720P will need less processing power so renders should be quicker.

Matt Davis · July 15th, 2008, 12:38 PM

And if you shoot 1080i, then de-interlace, it won't be better than 720p native.

I'm shooting 720p25 and loving the results on SD (PAL) DVD. I could make some hefty claims of EX1 vs Z1, but will ease off for now. Compressor does a great job in frame mode. FCP needs to ensure that the sequence is set to progressive, else it will look awful.

On the other hand if you shoot 720p50 and use compressor with frame controls enabled, it will downscale to SD and then re-interlace your 50p to 50i.

Our American friends will have more of an issue with pull-down and 60i to 24p to 29.97 and the rest, sorry I can't be more specific on this very complex state of affairs.

Rob Collins · July 15th, 2008, 01:35 PM

That's interesting--I didn't use frame mode in Compressor, nor have my FCP DV50 sequence set to progressive. I just made those changes, but can't see a difference.

When I burn to DVD (final destination), the clip encoded in Compressor has some flicker at the top of the letterbox, while the one encoded in FCP doesn't. I only see it on the DVD, not the QT file.

Thanks for the help.

Brett Wallace · July 15th, 2008, 06:26 PM

Anyone know when the clip browser S/W ver2 will be available, as this should bring some help to the SD down convert problem...

July 10th, 2008, 10:48 PM	#1
Rob Collins Major Player Join Date: Jul 2007 Location: Richmond, VA Posts: 229	1080 or 720 for best SD downconvert? I'm about to do the 48 hour film project, shooting on EX1 / Letus Extreme. The film must be delivered as a 4x3 SD QT file. My plan is to edit FCP in HD / EX native, export, then drop the file into a DV50 timeline (letterboxed), render and export again. First, does that sound like a good workflow? Even though it's SD delivery for the competition, I want to have it in HD too. But to the main question: does 720 downconvert better than 1080 or vice versa? I've done a simple test and can't see a difference, but wondering about different shooting situations, etc. Having slow motion available leads me to want to shoot 720. In my tests, the one thing that DIDN'T look good was a 720 slow motion clip brought into a 1080 sequence then downconverted. Thanks for any advice.

July 15th, 2008, 11:23 AM	#4
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	720P will need less processing power so renders should be quicker. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

July 15th, 2008, 12:38 PM	#5
Matt Davis Trustee Join Date: Aug 2005 Location: Berkshire, UK Posts: 1,562	And if you shoot 1080i, then de-interlace, it won't be better than 720p native. I'm shooting 720p25 and loving the results on SD (PAL) DVD. I could make some hefty claims of EX1 vs Z1, but will ease off for now. Compressor does a great job in frame mode. FCP needs to ensure that the sequence is set to progressive, else it will look awful. On the other hand if you shoot 720p50 and use compressor with frame controls enabled, it will downscale to SD and then re-interlace your 50p to 50i. Our American friends will have more of an issue with pull-down and 60i to 24p to 29.97 and the rest, sorry I can't be more specific on this very complex state of affairs. __________________ Director/Editor - MDMA Ltd: Write, Shoot, Edit, Publish - mattdavis.pro EX1 x2, C100 --> FCPX & PPro6

July 15th, 2008, 06:26 PM	#7
Brett Wallace Tourist Join Date: Jan 2008 Location: Central Coast Australia Posts: 2	EX clip browser Ver 2 Anyone know when the clip browser S/W ver2 will be available, as this should bring some help to the SD down convert problem...

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July 11th, 2008, 07:11 AM	#2
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	IMHO, downconverting interlaced footage to SD looks pretty crappy. It's hard to avoid interlace flicker. Therefore, any de-interlacing you can do before you downconvert, I think, is always helpful. My preference is to work with 720p files. I would also suggest NOT using any in-camera DETAIL...turn it off in the menu. Camera sharpening makes downconvert much harder and increases flickering on horizontal lines in the footage. If needed, apply post-process sharpening after downconvert.

July 15th, 2008, 10:47 AM	#3
Rob Collins Major Player Join Date: Jul 2007 Location: Richmond, VA Posts: 229	I've just done some tests and concluded that FCP does a better downconvert than Compressor, and takes less time. Here's two clips you can download, comments welcome: http://idisk.mac.com/robcollins-Public I also determined that there was no noticeable (to me at least) difference in downconverting 1080 vs. 720. 30p seems to do a bit better than 24p.

July 15th, 2008, 01:35 PM	#6
Rob Collins Major Player Join Date: Jul 2007 Location: Richmond, VA Posts: 229	That's interesting--I didn't use frame mode in Compressor, nor have my FCP DV50 sequence set to progressive. I just made those changes, but can't see a difference. When I burn to DVD (final destination), the clip encoded in Compressor has some flicker at the top of the letterbox, while the one encoded in FCP doesn't. I only see it on the DVD, not the QT file. Thanks for the help.