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Old March 3rd, 2011, 07:15 AM   #1
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Slow motion

I wish to hear some ideas here please. I need some footage to be played at 50% slow mo. The end product willl be high definition on Blu-ray. I have a JVC HD100 camera which as you know can shoot in HDV 720 25p and also HDV SD50p. Shooting in HDV 720 25p will give me a good resolution picture but a jerky 50% slow mo, which I don't want. Shooting in HDV SD50p will give me a lower resolution picture, since its SD, but perfect 50% slow motion. So my question is about the end resolution of the clip. If I use the SD50p format, slow it to 50% and then render it (uprez it) to 1280x720p will I have the same resoltion as if I slow the HDV 720 25p to 50%? Hope I explained myself clear enough!!
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Old March 3rd, 2011, 10:30 AM   #2
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Re: Slow motion

George,
there is a simple answer concerning spacial resolution. 720P format will give you 1280x720 format, while SD will give you 720x576 (in 50Hz/PAL regions). Even if you uprez SD-recorded media to HD720P, the spacial resolution will not increase - it stays at 720x576.

However, spacial resolution is one thing, and time resolution is another. If you produce a 50% slowmo from 720P/25, you will get a time resolution of only 12,5 fps, which will look very bad. Her the overall video quality would be much better, if you use SD 50P recorded media, produce a 50% slomo from it, and uprez to HD720P. The spacial resolution is lower, hoowever, the overall video quality is better due to fluid 25 fps.
Joachim
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Old March 3rd, 2011, 10:41 AM   #3
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Re: Slow motion

Thanks Joachim for you idea. Infact thats the way I think about it too. Anyone who has a different opinion on this issue? Thanks once again for your help
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Old March 3rd, 2011, 10:44 AM   #4
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Re: Slow motion

One more thought. Lets say that the SD50p does not exist on the HD100, would this mean that it is impossible to have decent slo mo in HD??!!
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Old March 4th, 2011, 06:32 AM   #5
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Re: Slow motion

First point: GY-HD100 does record standard definition 50p and 60p, as well as 50i and 60i.

Second point: With HD720p the HD100 records only 24p, 25p, and 30p. For a good slomo a recodrding framerate of 50p or 60p is preferrable. May be you can get a good HD-slomo with converting HD 720P/25 into HD720P/50 and then run it with half the speed in the editor. A software which can do this is TMPGEnc 4.0 XPress from Pegasys Inc.

Joachim
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Old March 4th, 2011, 01:11 PM   #6
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Re: Slow motion

I made some test with HD-video shot with my former GY-HD101E in 720p/25. So the original material is what your HD100 will produce (the HD101E was the European version of the HD100 with recording enabled).

I transcoded the clip into a 720P50 DNxHD120 for using it within Avid Media Composer. In a second transcoding I produced a 720p/25 DNxHD90 also for using withib´n Avid MC.

With Avid MC I created two projects, one 720p/50 and another one with 720p/25. With both projects I imported the transcoded clip of the corresponding framerate and produced 50% slomos from both projects. I jave then exported the rendered clips into Quicktime Movie files (DNxHD-coded).

The 50fps slomo is very good with smooth foreground moviement and also a good background movement.
The 25fps slomo is also of good quality with good foreground movements and slightly jerky background movements.

Summary: I would advise you to take your shots with HD720p/25, use TMPGEnc 4.0 XPress and transcode it into 50fps clips, and then produce a slomo in your editing applcation with a 720p/50 project setting. This will give you HD-resolution with a good time resolution.

Unfortunately, i cannot attach the QT-files (too large). However, I could e-mail them to you, if you send me you e-mail adress.

Good luck,
Joachim
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Old March 7th, 2011, 05:25 PM   #7
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Re: Slow motion

On my HD110 I've done a fair amount shooting SDHDV 60p (in US) at 480x960 60p... importing them, uprezzing to 720p then in Final Cut Pro's Cinema Tools chaning the framerate (1 click and it's done) reflagging it to 24p and get sweet slow motion that looks like it was shot in 720p.

Try that method with your PAL HD110.
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Old March 8th, 2011, 02:42 PM   #8
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Re: Slow motion

Yes I will try this for sure!! Thanks
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