Line Twitter

[Daniel Alexander]

Hello, does anybody have any idea why or how i can remove the inevitable line twittering that i get anytime i film something with fine detail (and sometimes not fine detail) on my ex1. It usually happens when i film something black with horizontal or vertical lines but alot of the times it happens on everyday objects like rails posts, leaves, bill board posters. By line twittering I mean that by filming a stationary object such as the head of a Phillips screwdriver, when the image is played back the screwdriver head will have twittering lines on it that seem to move as if I applied a scribble affect to it and ruin the footage.

from the lack of posts on this subject i assume its something i dont need to worry about too much but i would like to know why i always see it. to be more specific, i use vegas 8, monitor on crt and lcd monitors and output to a sd jvc broadcast monitor and domestic tv, the twittering is evident on all screens but less so on my pc monitors. I am shooting using Bill's tcp2 PP and in 1080p 25 HQ.

I haven’t tryed to burn a project off onto dvd yet as my dvd writer is broken and awaiting a new one, so maybe this is something that disappears when the footage is transcoded to sd? Any help would be great.

Thanks

[Bill Ravens]

Flickering/twitter is the bane of HD to SD downconvert. There are other posts discussing this problem. Like:
http://www.dvinfo.net/conf/showthread.php?t=116196

The problem is made worse by sharpening the video. To minimize twitter, you can turn off DETAIL in the EX1 menu and sharpen in post(after you downrez). Some people actually recommend adding BLUR prior to downrezzing to mitigate the problem.

[Steven Thomas]

This makes me wonder what the big guys are doing to minimize this with hollywood transfers to DVD. No twitter there, and they were for sure not shot is SD ;)

[Daniel Alexander]

Thanks Bill, it's as i thought...not much i can do about it without compromising picture quality (adding blur etc). I guess it's one of those things one has to live with and do what they can to avoid it aslong as this is a general problem for HD and not just the EX1 otherwise in a heartbeat i would sell this camera and get a canon a1 with a letus because this problem really can ruin a beautiful image and sometimes you dont see it until it's too late.

[Greg Hawkes]

I have had this problem.

My best result so far is in PAL land filming 720/50P edited in Vegas using project properties set to same and render to DVD Architect wide screen PAL fields set to none . Tried std setting for video 'Good' and also 'Best' does not make any difference. The finished DVD looks very good without line twitter on an LCD tv but some line twitter on a CRT TV. (much worse when filming 1080i or any interlaced format.

Gaussian blur gets rid of the twitter but defocuses the picture.
Currently trying Median effect on horizontral part of pic. Will report back.

[Daniel Alexander]

Thanks Greg, would love to hear some solid feedback. Do you know if the A1 suffers from such problems?

[Greg Hawkes]

Should have said vertical part of picture. I am sure I will be corrected.

[Paul Kellett]

Originally Posted by Greg Hawkes

I have had this problem.

My best result so far is in PAL land filming 720/50P edited in Vegas using project properties set to same and render to DVD Architect wide screen PAL fields set to none . Tried std setting for video 'Good' and also 'Best' does not make any difference. The finished DVD looks very good without line twitter on an LCD tv but some line twitter on a CRT TV. (much worse when filming 1080i or any interlaced format.

Gaussian blur gets rid of the twitter but defocuses the picture.
Currently trying Median effect on horizontral part of pic. Will report back.

That's my best result also,BUT with render field set as interlaced,upper field first.1080/50i also looks as good but is a bitch to edit,crap on 2nd monitor whereas 720/50p is nice to edit. I've done loads of experiment with all this

Paul.

[Daniel Alexander]

seeing as this doesnt seem to be a new problem, how have people been getting round this in the past? Surely theres a way to beat the line twitter problem without the option of getting your footage processed by an expensive video production lab

[Steven Thomas]

This was my point I made earlier...
Any ideas?

[Bill Ravens]

Don't know if you guys have tried the path thru virtualDub or not. This filter works fairly well..

http://compression.ru/video/deflicker/index_en.html

[Daniel Alexander]

Great find Bill, however i know i may sound somewhat 'spoilt' but after spending nearly £5000 on this camera i was hoping i wouldnt have to apply filters and lengthy multi-render paths to get a stationary image to stop jumping around. Maybe this is something that comes with working in HD or maybe this is more of a problem with the EX1, im very eager to know this as i believe this is the ONLY shortcoming i would ever consider selling the camera on. I can live with cmos behaviour and what have you but line twitter is something that will affect the type of work i do too much, and upon researching this camera before purchase i never heard of this problem, thats why i assume its more to do with HD rather than the camera

[Piotr Wozniacki]

Originally Posted by Daniel Alexander

i use vegas 8, monitor on crt and lcd monitors and output to a sd jvc broadcast monitor and domestic tv, the twittering is evident on all screens but less so on my pc monitors. I am shooting using Bill's tcp2 PP and in 1080p 25 HQ.

Daniel,

I went through this pain the hard way with my V1E last year - you can do the search for "line twitter" in the V1 forum to see the long discussion of the phenomenon between Bob Grant, Steve Mullen and myself :)

From what you are saying above I'd think that your other displays cannot distinguish progressive from interlaced, and try to de-interlace the signal - hence the line twitter. To check, try to playback the same clip on your PC screen using VLC or Nero Showtime and set Deinterlace=Bob. You will probably see the same twitter on your PC monitor as well...

Anyway, this is purely a display device problem. EX1 does NOT twitter itself!

[Steven Thomas]

Well put Piotr.

[Daniel Alexander]

Piotr, thats all i needed to hear :) Thank you