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interlacing / progressive etc,,,questions.
I havn’t posted on here in quite a while, so I don’t know if anyone here remembers me but hello anyway, and I hope your all doing ok !
OK guys, I’ve been trying to figure out this one on my own for a while… searching forums and reading up on whatever I can find on google, but I find contradictions wherever I look.
One question always seems to raise another, so I think it’s probably best to explain what I do and what I’m trying to do.
I shoot with an Sony FX1 / PAL / 25fps, and edit using Cineform Aspect HD… within Premiere Pro 2 ofcourse.
I shoot music videos mostly, and most of the time they are bluescreen videos, so I render my shots in the Premiere Pro timeline to be keyed in After Effects.
To get a better key I usually render in progressive mode HDV. At the end of the day my clients get their videos in standard def on DVD, Digi Beta, whatever.
OK here is my question.
1. When I render my captured footage (which is interlaced HDV), to 1440×1080 set to progressive mode, am I losing quality, or I should say, am I losing resolution ? I have checked and checked by zooming in on the images in the timeline, and I see no loss of quality in my images, if anything, as still images… they always look better in progressive mode.
I understand that interlaced video shows 50 images per second, e.g. frame 1 shows field 1 then field 2 and so on for all of the frames.
Now, if the two fields are combined when converted to progresive scan, I can understand that the two fields become one, resulting in lower res…but as interlaced images are only really displaying half an image at 1/50th of a second anyway, the other half of the image isn’t there to see anyway…am I right ?
If I am right then does this mean that technically you are losing resolution, but to the human eye you are not really losing it because when interlaced, the interlaced image is flickering so fast that you can’t see the half of the image that isn’t present ?
I’ve just shot a film trailer in HDV, and worked interlaced, but when rendered in progressive mode the motion in the image isn’t quite as smooth, which I like because it looks more like film than video. It gives me some motion artifacting but I can live with that, but am I losing resolution ?
Something that is also bugging me is that sometimes when I watch the interlaced footage in windows media player, I can see the lines where there is motion, and other times when I view the same footage, I don’t see them. Does anyone know why this could be happening ?
Anwyway, thanks for your help.
Cheers,
Steven.
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13 Replies
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I figured out the last bit. The image shows the lines in Nero, but not in Windows Media Player.
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Hi Steven,
I’ll start with this: Why aren’t you shooting progessive?
Converting interlaced to progressive using Premiere is almost always a bad idea. Yes, you will lose resolution, and you have explained the process very well in your post.
If you are looking at the footage in the Preview window, you may not see a difference, because that window isn’t really showing you the actual output. You would have to see the 2 videos side by side on a true HD monitor.
Now, you did say that your clients were getting their cuts in SD, so that part may be less of an issue. Progressive might in fact not even be seen as progressive, unless they are watching it on a plasma.
You also mentionned exporting to HDV. If those are music videos (short sequences), there is no reason why you shouldn’t be exporting uncompressed. HDV is very much on the edge for (HD) keying quality, and any effects or titles applied to the footage will require a new compression.
Cheers,
Vince
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I believe the newest vesions of WMP will automatically use hardware deinterlacing if it’s available on your card.
Vince
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Thanks Vince,
I’m not shooting progressive because I’m working with an FX1, I wish I could.
I really do need to get my hands on a Hi Def monitor too, to compare.
When looking through the manual for Cineform, I found that under the Cineform settings you can actually use that to render to progressive, and doing it this way has produced a better result on a slow motion shot that I’ve been experimenting with. I’m not getting as much motion artifacting on it.
If your curious to see the results of my little experiment, it’s a three minute trailer which can been seen here: https://www.youtube.com/profile?user=stevenpw
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Steven,
First, let me say, great work!
Deinterlacing really won’t show as much in SD, and especially not on YouTube. But I’m sure you will find a noticable difference when this is seen in HD.
I’m also pretty sure that Cineform will yield to better results than PP2; I haven’t seen side by side results, so I can’t really give you my opinion of this…
Somehow, I thought the FX1 had a progessive mode, I must have thought of a different model.
Cheers,
Vince
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Thanks Vince,
What I’ve found today, while experimenting with rendering, is that the shot of the Chinese guy near the start, as he looks over his shoulder, I’ve slowed it down considerably.
When interlaced the motion of his turning looks smooth… in progressive mode it doesn’t look so good… but when I rendered it in progressive mode using the setting in Cineform and not Premiere, the motion was as good as it looked when interlaced.
Thanks again,
Steven.
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Vince,
Is it better to do the conversion (interlaced to progressive) in After Effects ?, and if so do you know of any good online tutorials ?
I’ve heard there are different methods, one being that you use the 3:2 pulldown, which I’ve not attempted before, or should I post this question in the after effects forum ?
Thanks,
Steve.
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Unfortunately, I don’t think anyone will be able to tell you that there is a perfect science. There are hardware systems that do a pretty good job at it (Yep $$$$$), but from what I’ve seen from my own experiments, it all depends of the footage you are working with.
I would definitely post on After Effects as well, or at least look at the archives, I’ve seen it discussed many times. You will also get many more suggestions here during the week.
Vince
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I have a Z1 and an A1U and have spent a lot of time with Cineform about progressive from them. They recommend shooting 50i (I can with the Z1 but can’t with the A1U) – 25 cineframe and capturing with HD LINK in 24p WITH a 4% reduction, creating 24p, then editing that. This is supposed to be the best way because the 60i camera has to fluctuate in the pulldown to come to 24p. The 50i is a constant 2 to 1 to get to 25p. Incidentally, I think your footage looks great, however you did it.
They have a good article at
https://cineform.com/products/TechNotes/SonyHDVSupport/CineFrame.htm -
You have several options to capture with CineForm…one is to use HD Link which is their specific capture utility, which has the capability to convert the material on import between progressive/interlaced…and framerate changes.
While that would work fairly well, I might think you would like to try editing interlaced and moving the entire project into AE (you can just load the PPro project) and do your effects, then render out of AE as SD progressive and do both of those conversions simultaneously, making sure that options like motion blur, or frame blending (as clip-appropriate) are turned on. Carrying interlaced into AE allows you to still have both fields to work with when doing effects like slo-mo, instead of cutting your resolution in half when you export a clip deinterlaced.
I think you might be able to see some improvement this way, however, as Vincent states, it’s not an exact science and the shot content has as much to do with how it interlaces/deinterlaces as anything else.
TimK,
Director,
Kolb Productions,Creative Cow Host,
Author/Trainer
http://www.focalpress.com
http://www.classondemand.net
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