* * Artifact -

Derrick Begin · November 2nd, 2002, 09:23 AM

Post to the boards...

I've included a link to an example of my problem.

http://www.dpbegin.com/Gallery/Artifact.htm

This only occurs in two frames at a time. I have a feeling it has to do with the interlacing or something. Is there a way to smooth this out so it doesn't occur? I think it reared its ugly head because of my actor's or a sharp camera movement on my part.

Please help...

Thank you in advance...

Cheers!

Derrick

Andre De Clercq · November 2nd, 2002, 01:12 PM

Plse tell us more about this image. Directly out of yr cam on pauze? Out of yr NLE ? Seen(taken)from a PC screen? Cam settings? "two frames at a time" means two consecutive frames affected?

Derrick Begin · November 3rd, 2002, 10:07 AM

This was after the footage was captured from my XL1S, via Firewire, by Avid Express DV 3.5.

As I was editing the sequence, the 'shifting' took place. When I investigated by moving forward in the sequence, frame by frame, the two frames in sequential order were effected. The rest is fine. This is the raw footage and has not been altered in anyway, via color correction or blow-up. Which I plan to do.

The frame was exported from Avid (Quicktime) and posted raw.

Have you (anybody) come across this before?

Thanks for help and the options...!

Cheers!

Derrick

Andre De Clercq · November 3rd, 2002, 11:07 AM

Do you see the same artifact on the original footage played back in yr XLS, and/or outputed back to tape ? . Although you didn't process the data you have at least decompressed the DV data by the Avid Codec in order to visualize this image. Could you also confirm if the head was turning and the cam was handheld ? (in the neighbouring frames). All those questions because I suspect yr Avid Codec (decompressor). DV is basically a MJPEG concept. So it's an intraframe system, but one of the "extra's" applied in DV is the macroblock aproach and this allows interframe compression under some conditions. The decision algorithm about reusing parts of the foregoing frame can go wrong under very specific content conditions. It's also quite possible that Avid uses a stripped-down decompressor just for computer visualisation (saves processing power for the real work), and applies the full version for editing (cross overs...)

Derrick Begin · November 3rd, 2002, 04:19 PM

Thanks Dre...

I am going to look into that tonight, checking it out on my XL1S.

I'll get back to this when I can scrutinize the frames later.

Thanks, again!

Derrick

November 2nd, 2002, 09:23 AM	#1
Derrick Begin Major Player Join Date: Jun 2002 Location: New York Posts: 329	*** * Artifact - - Motion? Cleaning? **** Post to the boards... I've included a link to an example of my problem. http://www.dpbegin.com/Gallery/Artifact.htm This only occurs in two frames at a time. I have a feeling it has to do with the interlacing or something. Is there a way to smooth this out so it doesn't occur? I think it reared its ugly head because of my actor's or a sharp camera movement on my part. Please help... Thank you in advance... Cheers! Derrick

November 3rd, 2002, 10:07 AM	#3
Derrick Begin Major Player Join Date: Jun 2002 Location: New York Posts: 329	*** * PROMPT * *** This was after the footage was captured from my XL1S, via Firewire, by Avid Express DV 3.5. As I was editing the sequence, the 'shifting' took place. When I investigated by moving forward in the sequence, frame by frame, the two frames in sequential order were effected. The rest is fine. This is the raw footage and has not been altered in anyway, via color correction or blow-up. Which I plan to do. The frame was exported from Avid (Quicktime) and posted raw. Have you (anybody) come across this before? Thanks for help and the options...! Cheers! Derrick

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November 2nd, 2002, 01:12 PM	#2
Andre De Clercq Major Player Join Date: Sep 2002 Location: Belgium Posts: 804	Plse tell us more about this image. Directly out of yr cam on pauze? Out of yr NLE ? Seen(taken)from a PC screen? Cam settings? "two frames at a time" means two consecutive frames affected?

November 3rd, 2002, 11:07 AM	#4
Andre De Clercq Major Player Join Date: Sep 2002 Location: Belgium Posts: 804	Do you see the same artifact on the original footage played back in yr XLS, and/or outputed back to tape ? . Although you didn't process the data you have at least decompressed the DV data by the Avid Codec in order to visualize this image. Could you also confirm if the head was turning and the cam was handheld ? (in the neighbouring frames). All those questions because I suspect yr Avid Codec (decompressor). DV is basically a MJPEG concept. So it's an intraframe system, but one of the "extra's" applied in DV is the macroblock aproach and this allows interframe compression under some conditions. The decision algorithm about reusing parts of the foregoing frame can go wrong under very specific content conditions. It's also quite possible that Avid uses a stripped-down decompressor just for computer visualisation (saves processing power for the real work), and applies the full version for editing (cross overs...)

November 3rd, 2002, 04:19 PM	#5
Derrick Begin Major Player Join Date: Jun 2002 Location: New York Posts: 329	Thanks Dre... I am going to look into that tonight, checking it out on my XL1S. I'll get back to this when I can scrutinize the frames later. Thanks, again! Derrick