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SCREEN JERKYNESS IN MULTIPLE PROGRAMS

Discussion in 'Video to DVD' started by born1974, Mar 25, 2005.

  1. born1974

    born1974 Member

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    My question is how do i get rid of screen jerk. I know frame rate has a part,feild order has a part and maybe interlace or progressive. those last 2 i have know idea what they mean. most all the avi files i use say there non interlaced and i convert them to dvd mpeg2. but i don't know if there being interlaced in that process or not usually i just set a feild order top or bottom.
    When a file says 23.976 fps i use 3:2 pulldown allways. if it's 29 fps i use 29 for my output. so how could there be screen jerk from that. canopus asks for a feild order but i don't know the source feild order. TMPEGEnc asks for interlaced or progressive, but only for the source. I use interlace for that. I also have all the good codecs so i don't think that's a problem.
    Also what does it mean when it says that it stores frames instead of feilds can i change it to feild and it will play back smoothly. I hope this is somthing simple that someone help me out with. THANX
    Actually i'm not sure if the files i'm useing are iterlaced or not. how can i tell.
     
    Last edited: Mar 25, 2005
  2. pfh

    pfh Guest

    Yeah I know the feeling. When I start reading up on progressive and interlaced info it gets confusing. But from what I understand:
    Your file says 23.9 fps- that would indicate a progressive film source. Cinema film is ~24fps, frame by frame display. By using 3:2 pulldown that same film can be displayed on tv which runs at 29fps (actually it's doubled to 60fps but that's another part to the tv equation). Some refer to 3:2 pulldown as telecine. In a nutshell this process adds 2 interlaced frames to every 3 normal frames. Thus you'd have a mix of progressive and interlaced frames.

    Your file says 29fps- that would indicate an interlaced source or possibly a mix of progressive and interlaced.

    Now when it comes to tv and the use of fields instead of frames is where things get confusing. For broadcasting reasons and tv refresh rates frames get chopped into a top and bottom to create fields. This allows our eyes to see fluid motion. In essence each top and bottom frames are shown at 30fps giving us a total of 60fps.

    It is my belief that commercial vhs tapes are actually a mix of 3 progrssive frames and 2 interlaced due to the telecine process made to create them. However, capturing a tv broadcast you'd get a totally interlaced file. Also, homemade tapes are most likely all interlaced. I can not find anyone that has explained this to me in these terms but as I said, from my reading of telecine and other info this is what I've come to assume.

    I am not an expert and don't take my word as truth, I could be way off- just trying to help out a layman like myself.

    Now regarding your situation- what are your actual sources? I'd say with those 24fps files it's best to leave 'em at 24 progressive and let your dvd player apply it's 2:3 pulldown if it has it. The 29fps stuff could be commercial vhs or home made. For commercial tapes (haven't found a dfinitive answer) my situation I have to cap progressive and the end product is fine. Viewable on tv and pc. If commercial tapes are a mix of progressive and interlace as I suspect, then leaving as a progressive capture is ok. On the other hand, if you are working with home made interlaced stuff you'd leave 'em as interlaced (30fps). Unfortunatly I've done (converted) no home made tapes really so can't give more advice. And in your situation it's my guess you are not choosing the right A) Field order if it's interlaced or B) interlacing progressive material when you shouldn't. Does that make sense?

    Hope I didn't insult you- just trying to educate myself and help. Hope I didn't confuse you more either but I do hope some experts contribute to this thread so we both can benefit.
     

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