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Old March 22nd, 2006, 02:54 PM   #1
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On the subject of HD downconversion...

I've seen some discussion here in another thread about downconversion and specifically, how to do it in FCP. Here's my two pennies...

I've found wildly varying results while trying to downconvert with the Apple FCP suite, depending on how one goes about it. Here's the three methods I've tried and the results I got:

1-Downconverting in an FCP timeline: This method is taking your cut HDV sequence, and copying and pasting it into an SD timeline, either DV or what have you. FCP will automatically scale your HDV clips to SD size (letterboxed), but any sort of output this way seems to net the worst results out of all the methods I've tried....even with the sequence "Motion quality" turned to "Best". Downconversion is very soft, with scaling artifacts.

2-Downconverting via Export: This is cutting in HDV, then exporting a Final Cut movie via File Export, then selecting an SD "type". This, for me, nets much better results than method number one, but affords no control whatsoever. Scaling artifacts are greatly reduced, almost perfect.

3-Downconverting via Compressor: This method works best for me. In this method, I either export a finished HDV timeline via compressor to 10bit uncompressed SD, OR recompress all my original HDV media to 10bit uncompressed BEFORE the edit, then cut in an uncompressed timeline.

This last method also gives you the choice of doing a center-cut 4:3 extraction from your HDV, or going letterbox. In addition, it gives you the ability to add edge enhancement to your downconvert, which is very important, via the filters available in a Compressor preset. When downconverting HD material, the edge enhancement the camera adds gets lost when the frame is scaled down. This allows you to add it back in, and exert fine control over the process. Which brings us to the subject of...Edge Enhancement

I expect somebody is going to say, "Well, I shoot WITHOUT edge enhancement to mimic the way film works". Something most people don't think about is that in most high-end telecine transfers, the colorist adds some edge enhancement. Skeptical? Here's a frame grab (and blow-up) from a music video that shot on 35mm, and was digitized uncompressed from the Digibeta telecine master:

http://homepage.mac.com/nweaver/.Pic...lframe35mm.jpg
http://homepage.mac.com/nweaver/.Pic...35mmDetail.png

See that 1.5 pixel halo? Didn't come from the negative :-)

One last tidbit, with pics. In another unrelated thread, on another board a couple weeks ago, I posted two frames. One from the same 35mm material above, and one downconverted from HD100 material. I had the good fortune of both frames being of downtown Los Angeles at magic hour. The HD100 frame is downconverted via Compressor:

http://homepage.mac.com/nweaver/.Pictures/1.tif
http://homepage.mac.com/nweaver/.Pictures/2.tif

Can you tell which is which? Downconverted correctly, things are pretty close!

Sorry for the classroom vibe, but I've been meaning to share all this with people for a while now, but I knew it was going to be a long post!
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Last edited by Nate Weaver; March 22nd, 2006 at 04:02 PM.
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Old March 22nd, 2006, 04:05 PM   #2
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Greatly appreciated, Nate! Thanks for the education and keep those lessons coming.
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Old March 22nd, 2006, 04:10 PM   #3
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Quote:
Originally Posted by Nate Weaver
I've seen some discussion here in another thread about downconversion and specifically, how to do it in FCP. Here's my two pennies...

I've found wildly varying results while trying to downconvert with the Apple FCP suite, depending on how one goes about it. Here's the three methods I've tried and the results I got:

1-Downconverting in an FCP timeline: This method is taking your cut HDV sequence, and copying and pasting it into an SD timeline, either DV or what have you. FCP will automatically scale your HDV clips to SD size (letterboxed), but any sort of output this way seems to net the worst results out of all the methods I've tried....even with the sequence "Motion quality" turned to "Best". Downconversion is very soft, with scaling artifacts.

2-Downconverting via Export: This is cutting in HDV, then exporting a Final Cut movie via File Export, then selecting an SD "type". This, for me, nets much better results than method number one, but affords no control whatsoever. Scaling artifacts are greatly reduced, almost perfect.

3-Downconverting via Compressor: This method works best for me. In this method, I either export a finished HDV timeline via compressor to 10bit uncompressed SD, OR recompress all my original HDV media to 10bit uncompressed BEFORE the edit, then cut in an uncompressed timeline.

This last method also gives you the choice of doing a center-cut 4:3 extraction from your HDV, or going letterbox. In addition, it gives you the ability to add edge enhancement to your downconvert, which is very important, via the filters available in a Compressor preset. When downconverting HD material, the edge enhancement the camera adds gets lost when the frame is scaled down. This allows you to add it back in, and exert fine control over the process. Which brings us to the subject of...Edge Enhancement
!
Good stuff Nate. It reinforces what my friend Council (from the soul group "Maurice and Council") posted recently. Seriously, Council had the same method and results as yours regarding downconverting and for those of us that are doing a lot of it for broadcast it's definitely the way.

Previously when mixing 16:9 SD footage (i.e. XL2) with 4:3 for broadcast and DVD distribution dropping the XL2 footage into a standard timeline worked fine, but downressing is a whole other challenge and the 10 bit uncompressed through Compressor, is the way to get great looking HD footage out to SD.

Thanks professor...and I guess jpeg 2.
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Old March 22nd, 2006, 05:27 PM   #4
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Thanks. This is great to know!
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Old March 22nd, 2006, 06:41 PM   #5
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Quote:
Originally Posted by Jim Giberti
Good stuff Nate. It reinforces what my friend Council (from the soul group "Maurice and Council") posted recently. Seriously, Council had the same method and results as yours regarding downconverting and for those of us that are doing a lot of it for broadcast it's definitely the way.

Previously when mixing 16:9 SD footage (i.e. XL2) with 4:3 for broadcast and DVD distribution dropping the XL2 footage into a standard timeline worked fine, but downressing is a whole other challenge and the 10 bit uncompressed through Compressor, is the way to get great looking HD footage out to SD.

Thanks professor...and I guess jpeg 2.
which if any of these methods uses the AIC?

is the "compressor" a final cut plug in?
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Old March 22nd, 2006, 06:50 PM   #6
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Originally Posted by Brian Luce
which if any of these methods uses the AIC?

is the "compressor" a final cut plug in?
I use the term "HDV" above in reference to both AIC and native HDV timelines and media.

Compressor is an auxiliary program included with FCP since version 4 to do batch processing and exports. It works either standalone or as an export module of FCP.

Note all my comments refer to the FCP5 suite...Compressor prior to v5 wasn't so hot at scaling video.
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Old March 22nd, 2006, 06:53 PM   #7
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Quote:
Originally Posted by Jim Giberti
Good stuff Nate. It reinforces what my friend Council (from the soul group "Maurice and Council") posted recently. Seriously, Council had the same method and results as yours regarding downconverting and for those of us that are doing a lot of it for broadcast it's definitely the way.
hey jim,
i think i was the one who suggested going thru compressor in 10bit uncompressed and council was saying to go thru the sd timeline way. and i give all credit to nate, because on one of the threads i read, nate said to go with 10 bit in compressor. eversince i tried that way and loved the results, it's the only way i will downconvert from now on.
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Old March 22nd, 2006, 07:57 PM   #8
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Thanks for the info! I've been doing it the "worst" way. One question though:

Could you export the HDV sequence as DV NTSC using Compressor to avoid the huge file sizes? Would this result in lower quality than the 10 bit?

Thanks guys!
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Old March 22nd, 2006, 09:12 PM   #9
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Quote:
Originally Posted by Nathan VanHoose
Could you export the HDV sequence as DV NTSC using Compressor to avoid the huge file sizes? Would this result in lower quality than the 10 bit?
You could, and you'd still get very pretty pictures, but the color resolution when you do it the way I outlined becomes 4:2:2.

Downconverting to DVCPRO 50 would be a great stopping place in between if you can't go uncompressed.
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Old March 22nd, 2006, 09:20 PM   #10
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I tried to go DV and the exported video looks jittery and the aspect ratio is off. Do I have a setting that's not right?
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Old March 22nd, 2006, 09:37 PM   #11
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What kind of material from what camera in what mode?

[edit: well, yeah, there's a lot of settings to get right in Compressor. Maybe I'll post some Compressor presets to do this. Let me get dinner taken care of and I'll see what I can post]
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Old March 22nd, 2006, 09:55 PM   #12
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No Problem Nate.

The material is of a single speaker who moves but its relatively slow movement. I'm shooting in HDV mode on a Sony Z1U. Thanks again for your help.
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Old March 22nd, 2006, 11:00 PM   #13
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Okay, that's what I was suspecting. You're trying to go from interlaced HDV to interlaced SD resolution. I haven't made a preset for that, nor have I done any tests.

All of my presets and tests have been on progressive source media.
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Old March 23rd, 2006, 10:50 AM   #14
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Quote:
Originally Posted by Maurice Jolly
hey jim,
i think i was the one who suggested going thru compressor in 10bit uncompressed and council was saying to go thru the sd timeline way. and i give all credit to nate, because on one of the threads i read, nate said to go with 10 bit in compressor. eversince i tried that way and loved the results, it's the only way i will downconvert from now on.

Sorry about that Maurice...I always thought you were the better singer though. I think it was Nate that first inspired me to go out to Compressor 10bit rather than "export as" as well.
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Old March 23rd, 2006, 11:50 AM   #15
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Nate,

Ever tried editing in photojpeg? It might be the best compromise between HDV editing and finalizing in uncompressed. For 720/24 it should be around 7MBs with exceptional quality at 75%. Should downconvert via Compressor extremely well too.
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