image motion separation artifacts ( w example) at DVinfo.net

Les Dit · January 9th, 2006, 01:46 AM

I downloaded some hd100 clips from
http://www.dvxuser.com/V3/showpost.p...67&postcount=1

The shot of the guitar had a disturbing artifact, the details on the guitar neck move with independent motion from the surface they are attached to!
It's an mpeg motion estimation error, ofter seen on lower bit rate DSS tv broadcasting.

I cropped out a 640x480 from the clip, blew it up, and slowed it down a bit.
Objects slip slide over the dark brown wood. Logo decal, and the shiny parts. Otherwise very nice footage!

See the cropped example:
http://www.pixelharvest.com/hd/shake.m2t

-Les

Steve Mullen · January 9th, 2006, 02:34 AM

You describe the effect and its cause well. Its the first time I've seen any artifacting from 720 so I've got to ask - was the motion filter ON?

Mike Marriage · January 9th, 2006, 03:43 AM

Someone posted some footage of a dance show that showed some compression artifacting.

2 guys were swinging firworks around their head sending sparks everywhere whilst the cameraman zoomed out - i.e. about as tough as it gets for HDV. The artifacting was there, but the scene was so dynamic that it helped masked the problem. In generally ProHD seems pretty robust.

Marc Colemont · January 9th, 2006, 06:21 AM

Quote:

Originally Posted by Mike Marriage

Someone posted some footage of a dance show that showed some compression artifacting.

2 guys were swinging firworks around their head sending sparks everywhere whilst the cameraman zoomed out - i.e. about as tough as it gets for HDV. The artifacting was there, but the scene was so dynamic that it helped masked the problem. In generally ProHD seems pretty robust.

I posted this footage. It was captured with HDlink (mid-setting I found out later) And motion smoothing was ON. That could help the small artifact or not, I don't know.

Mike Marriage · January 9th, 2006, 06:43 AM

Quote:

Originally Posted by Marc Colemont

I posted this footage. It was captured with HDlink (mid-setting I found out later) And motion smoothing was ON. That could help the small artifact or not, I don't know.

Thanks Marc,

Do you mean it had been recompressed when captured or was that the natives files from the tape?

Marc Colemont · January 9th, 2006, 07:45 AM

I didn't know before that there was a capture setting in HDlink until last week.
Maybe a question I should to post in the Cineform forum to know exactly what these setting do to the captured image. Unless David from Cineform reads this post.
This week I will re-capture that footage again in the highest setting to check if I see differences...

Mike Marriage · January 9th, 2006, 08:27 AM

Quote:

Originally Posted by Marc Colemont

I didn't know before that there was a capture setting in HDlink until last week.
Maybe a question I should to post in the Cineform forum to know exactly what these setting do to the captured image. Unless David from Cineform reads this post.
This week I will re-capture that footage again in the highest setting to check if I see differences...

How are you finding the camera? Have you had any issues with the codec (or anything else serious)?

Stephen L. Noe · January 9th, 2006, 08:57 AM

Very cool how you found that!

I post those m2t's raw so you get what I get. It's funny how when footage get's posted, it becomes a "where's waldo" for errors. The sloppy camera motion is me monkeying with a cheap Libec M20. At regular reslution this minute slippage goes un-noticed unless you are looking for it with excrutiating detail.

Motion smoothing was on BTW for that shot.

Marc Colemont · January 9th, 2006, 09:55 AM

Quote:

Originally Posted by Mike Marriage

How are you finding the camera? Have you had any issues with the codec (or anything else serious)?

I don't have the long term experience yet, but yes I'm very happy with the camera. The shot I took were the the guys are playing with the pyro sticks is probably one of the most worst cases for the HDV codec to shoot.
I don't have an expensive HD-monitor, on my Laptop the result looks very good. At the same time another guy was filming the same thing with a Sony FX1. I bet his interleased video looks worse when you pause.

When I just bought the camera I had issues recording video. The JVC support promply replied the same day on my email to them to clean my heads. I'm a bold guy so I went strait to the bathroom to soap my head (just kidding).
After running the cleaning tape it works just fine. I saw afterwords on other forums that I was not the only one which needed to clean heads before usage. It was with different brands too.

January 9th, 2006, 01:46 AM	#1
Les Dit Major Player Join Date: Oct 2003 Location: Southern Cal-ee-for-Ni-ya Posts: 608	image motion separation artifacts ( w example) I downloaded some hd100 clips from http://www.dvxuser.com/V3/showpost.p...67&postcount=1 The shot of the guitar had a disturbing artifact, the details on the guitar neck move with independent motion from the surface they are attached to! It's an mpeg motion estimation error, ofter seen on lower bit rate DSS tv broadcasting. I cropped out a 640x480 from the clip, blew it up, and slowed it down a bit. Objects slip slide over the dark brown wood. Logo decal, and the shiny parts. Otherwise very nice footage! See the cropped example: http://www.pixelharvest.com/hd/shake.m2t -Les

January 9th, 2006, 02:34 AM	#2
Steve Mullen HDV Cinema Join Date: Feb 2003 Location: Las Vegas Posts: 4,007	You describe the effect and its cause well. Its the first time I've seen any artifacting from 720 so I've got to ask - was the motion filter ON? __________________ Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c

January 9th, 2006, 03:43 AM	#3
Mike Marriage Major Player Join Date: Sep 2005 Location: NE of London, England Posts: 788	Someone posted some footage of a dance show that showed some compression artifacting. 2 guys were swinging firworks around their head sending sparks everywhere whilst the cameraman zoomed out - i.e. about as tough as it gets for HDV. The artifacting was there, but the scene was so dynamic that it helped masked the problem. In generally ProHD seems pretty robust.

January 9th, 2006, 07:45 AM	#6
Marc Colemont Major Player Join Date: Nov 2005 Location: Belgium Posts: 695	I didn't know before that there was a capture setting in HDlink until last week. Maybe a question I should to post in the Cineform forum to know exactly what these setting do to the captured image. Unless David from Cineform reads this post. This week I will re-capture that footage again in the highest setting to check if I see differences...

January 9th, 2006, 08:57 AM	#8
Stephen L. Noe Trustee Join Date: Apr 2005 Location: Chicago Posts: 1,214	Very cool how you found that! I post those m2t's raw so you get what I get. It's funny how when footage get's posted, it becomes a "where's waldo" for errors. The sloppy camera motion is me monkeying with a cheap Libec M20. At regular reslution this minute slippage goes un-noticed unless you are looking for it with excrutiating detail. Motion smoothing was on BTW for that shot.