VideoHelp Forum
+ Reply to Thread
Results 1 to 22 of 22
Thread
  1. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    Hello!
    I have two Samsung R10 camcorders. They have 1080 50i mode.
    I use them for over-under 3D. (that means i scale images from both camcorders at 50% verticaly, and put one above another in Adobe Premiere.)
    When I open an interlaced 50i video in Premiere, it is automaticaly transformed in 25p. That is verry bad for 3D becouse I need high frame rate.

    So, my ideea is: why to perform deinterlacing and loose frame rate, and scale the resulted progresive image to 50% ? Instead, I should use the original fields as they are.
    Those fields in 50i are in my opinion 50 half frames, right? That is EXACTLY what i need...
    But how can I convince Premiere to give me the fields one after another as they are?

    I have tryed with VirtualDub with bob deinterlacing and bob doubler with poor results. First, it is very very SLOW. Second, instead of 50 frames, I get 100 frames, and I dont need extra fake frames or resolution.

    To resume, I DONT want deinterlacing, I DONT want frame doubling, I JUST WANT that every field to be considered a frame, AND YES, I need it at half resolution, exactly as it is in the camcorder.

    I wonder why aparently is no solution for such a theoreticaly simple problem.

    Thanks!
    Quote Quote  
  2. Originally Posted by omepheus View Post
    So, my ideea is: why to perform deinterlacing and loose frame rate, and scale the resulted progresive image to 50% ? Instead, I should use the original fields as they are.
    You can do this in AviSynth:

    Code:
    left=WhateverSource() # get left source video
    right=WhateverSource() # get right source video
    
    left=SeprateFields(left)  # undo interlacing, make fields sequential
    right=SeparateFields(right) # undo interlacing make fields sequential
    
    StackVertical(left, right) # stack the fields, reverse left/right if necessary
    But that will leave you with a picture that bounces up and down by one scanline with each frame (because the lower field is supposed to be viewed one scanline lower than the top field). In practice you probably won't notice it. A more perfect solution would be something like:

    Code:
    left=WhateverSource() # get left source video
    right=WhateverSource() # get right source video
    
    left=QTGMC(left) # turn each field into a frame, leaving the original scan lines in the original location
    right=QTGMC(right) # turn each field into a frame, leaving the original scan lines in the original location
    
    left=BicubicResize(left, 540) # reduce height to half
    right=BicubicResize(right, 540) # reduce height to half
    
    StackVertical(left, right) # stack the fields, reverse left/right if necessary
    By the way, the 100 fps problem in VirtualDub comes from a misinterpretation of the source video's properties. The video is 25 frames per second, each frame contains two fields, intended to be viewed separately, one after the other at 50 fields per second. But marketing dweebs started calling 25i "50i" because it sounds better. Then at some points engineering was forced to label those 25i videos as 50i so that customers wouldn't think they were being ripped off. But 25i and 50i are exactly the same thing. VirtualDub is seeing the video labeled 50i thinking that it's 50 frames per second, 100 fields per second.
    Last edited by jagabo; 25th Dec 2012 at 08:51.
    Quote Quote  
  3. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    I have never used avisynth. There are no executable files in the archive. Is it some sort of plug in for another program?
    Quote Quote  
  4. Originally Posted by omepheus View Post
    When I open an interlaced 50i video in Premiere, it is automaticaly transformed in 25p. That is verry bad for 3D becouse I need high frame rate.

    So, my ideea is: why to perform deinterlacing and loose frame rate, and scale the resulted progresive image to 50% ? Instead, I should use the original fields as they are.
    Those fields in 50i are in my opinion 50 half frames, right? That is EXACTLY what i need...
    But how can I convince Premiere to give me the fields one after another as they are?


    To resume, I DONT want deinterlacing, I DONT want frame doubling, I JUST WANT that every field to be considered a frame, AND YES, I need it at half resolution, exactly as it is in the camcorder.
    Set the sequence settings to 1080i50, and export settings in AME to 1080i50 and it will be the same as original : 1080i50 with fields intact

    It's only deinterlaced for the preview - internally it's still 1080i50
    Quote Quote  
  5. Originally Posted by omepheus View Post
    I have never used avisynth. There are no executable files in the archive. Is it some sort of plug in for another program?
    AviSynth works in the background. You control it with plain text scripts. You open those scripts with an editor or encoder (VirtualDub, for instance) just as if they were video files.

    http://avisynth.org/mediawiki/Getting_started

    The first script I gave you doesn't require any third party filters. The second script, the one with QTGMC() requires the QTGMC package, which in turn requires several others.

    http://forum.doom9.org/showthread.php?t=156028
    Quote Quote  
  6. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    for jagabo: thank you! You seem the only one to understand my problem.
    About avisynth, can i use it in premiere? Becouse i like the speed of mercury engine.
    Encoding full hd with virtualdub takes ages


    for poisondeathray:
    Originally Posted by poisondeathray View Post
    Set the sequence settings to 1080i50, and export settings in AME to 1080i50 and it will be the same as original : 1080i50 with fields intact

    It's only deinterlaced for the preview - internally it's still 1080i50
    Thanks, bur Preserving interlaced video is not what we are talking about here.
    Quote Quote  
  7. Originally Posted by omepheus View Post

    for poisondeathray:
    Originally Posted by poisondeathray View Post
    Set the sequence settings to 1080i50, and export settings in AME to 1080i50 and it will be the same as original : 1080i50 with fields intact

    It's only deinterlaced for the preview - internally it's still 1080i50
    Thanks, bur Preserving interlaced video is not what we are talking about here.

    But you said you don't want to deinterlace? If you want every field to become a frame, you bob deinterlace to 1080p50 (that is bob deinterlacing) . In jagabo's script, he is using QTGMC (that is a bob deinterlacer). Premiere's deinterlacing quality is very poor compared to QTGMC

    Proper vertical resizing of interlaced content requires deinterlacing (you can't just resize the fields)

    About avisynth, can i use it in premiere? Becouse i like the speed of mercury engine.
    Encoding full hd with virtualdub takes ages
    You cannot use avisynth with MPE
    Quote Quote  
  8. I forgot to mention that you'll also be left with more jagged edges with the first script, another reason to use QTGMC(). I don't know if you can open AviSynth scripts in Premiere. If nothing else you could open the script in VirtualDub then save an intermediate file. Or maybe use VirtualDub's frame server.
    Quote Quote  
  9. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    poisondeathray, I DO NOT WANT ANY RESIZE. I need 1920x540...

    By deinterlacing I understand the creation , by interpolation or any other method of a full 1920x1080 frame, based on original interlaced fields. That necesits CPU power, and that is EXACTLY what I want to avoid.

    What I need is a new file, of 1920x540 full picture, based of the original frames, but with ZERO processing, I want them as they are.
    This in my mind should be very simple becouse the computer doesnt need to compute anything, just rearange the data... But in practice, I see that such basic option is missing from video editing software.


    P.S.
    If the bob is doing this how you said, why I got only wrong results like 100 fps 1920x540 or 50 fps 1920x1080?
    I have 1080 50i input, and I need 1920x540 50 fps output. What bob filter should I select to make this?
    Quote Quote  
  10. Originally Posted by omepheus View Post
    I have 1080 50i input, and I need 1920x540 50 fps output.
    No, you have 1080 25i input. It's mislabeled as 50i. Just change the source frame rate to 25 fps in VirtualDub if you want to work there. It would best if you uploaded two sample videos from your camcorder.
    Quote Quote  
  11. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    no. the camcorder has:
    1080 50i
    1080 25p
    720 50p
    etc...
    Quote Quote  
  12. Originally Posted by omepheus View Post
    no. the camcorder has:
    1080 50i
    1080 25p
    720 50p
    etc...
    The mislabeling bites another one in the ass.

    50i refers to 50 fields per second, not 50 interlaced frames per second. 50i (50 fields per second) is the same as 25i (25 interlaced frames per second). If the camera manufacturers hadn't ever introduced this lousy naming convention, there wouldn't be these misunderstandings.
    Quote Quote  
  13. aBigMeanie aedipuss's Avatar
    Join Date
    Oct 2005
    Location
    666th portal
    Search Comp PM
    Originally Posted by omepheus View Post
    no. the camcorder has:
    1080 50i
    1080 25p
    720 50p
    etc...

    50i is a marketing term. it means 50 fields/sec not 50 frames/sec. it really is 25i.
    --
    "a lot of people are better dead" - prisoner KSC2-303
    Quote Quote  
  14. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    If they were frames, this topic would not exist in the first place, of course they are fields.
    And is no marketing term, if this cam knows 25p , it certainly knows 50i (not 25i )
    But what is a field? As I know, is half frame, right?
    So, there are 50 half frames. They can make 25 full frames, I know that, but as I said 5 times before, I DO NOT WANT 1080 25p. The camera have by default real 25p but I dont need it.
    Once again, I NEED 50 fps half frames (1920x540) from 1080 50i. Nothing more, and nothing less.
    Quote Quote  
  15. Originally Posted by omepheus View Post
    If they were frames, this topic would not exist in the first place, of course they are fields.
    And is no marketing term, if this cam knows 25p , it certainly knows 50i (not 25i )
    But what is a field? As I know, is half frame, right?
    So, there are 50 half frames. They can make 25 full frames, I know that, but as I said 5 times before, I DO NOT WANT 1080 25p. The camera have by default real 25p but I dont need it.
    Once again, I NEED 50 fps half frames (1920x540) from 1080 50i. Nothing more, and nothing less.
    Then use jagabo's original script from post #2 and call it whatever you like.
    Quote Quote  
  16. Originally Posted by omepheus View Post
    If they were frames, this topic would not exist in the first place, of course they are fields.
    And is no marketing term, if this cam knows 25p , it certainly knows 50i (not 25i )
    But what is a field? As I know, is half frame, right?
    So, there are 50 half frames. They can make 25 full frames, I know that, but as I said 5 times before, I DO NOT WANT 1080 25p. The camera have by default real 25p but I dont need it.
    Once again, I NEED 50 fps half frames (1920x540) from 1080 50i. Nothing more, and nothing less.
    Again, 25i and 50i are the same thing: 50 fields per second interlaced

    1080i50 is already 1920x540 as fields. If you separate the fields, you already have 1920x540 . The problem is fields are offset spatially. Even vs. Odd scanlines - if you just separate the fields, the even/odd fields will go up/down/up/down (it won't look normal when you view it) . This is why you need to deinterlace . Re read jagabo's initial post - that's why he was suggesting QTGMC in the 2nd script.

    If you want 50 fps half frames, without the spatial offset, you bob deinterlace (this converts 1080i50 to 1080p50 ie. each field becomes a frame), then resize to 540. This means you have 1920x540p50
    Quote Quote  
  17. Originally Posted by omepheus View Post
    If they were frames, this topic would not exist in the first place, of course they are fields.
    And is no marketing term, if this cam knows 25p , it certainly knows 50i (not 25i )
    If they were stored in the camera as individual 1920x540 fields/frames you might have a case. Since they aren't, you don't. When you transfer the video to the computer, how many frames per second are there? 25, not 50. The numbers (23.976, 29.97, 59.94, 25, even 50, they all traditionally refer to the FramesPS. Why all of a sudden do people decide a number refers to FieldsPS?
    Last edited by manono; 25th Dec 2012 at 20:59.
    Quote Quote  
  18. aBigMeanie aedipuss's Avatar
    Join Date
    Oct 2005
    Location
    666th portal
    Search Comp PM
    some ponies are one trick only, they can never learn. i refuse to beat my heat against a wall. bye.
    --
    "a lot of people are better dead" - prisoner KSC2-303
    Quote Quote  
  19. Once again, 50i is exactly the same thing as 25i. The camera shoots 50 fields (half pictures) per second. They come out of the decoder as 25 interlaced frames per second, 25i (the number refers to the frame rate, i or p indicates whether those frames are on picture or two half pictures). This has always been the case with interlaced digital video. But since one manufacturer started calling it 50i all the others had to follow suit. Otherwise they would lose sales to the superior sounding 50i.

    The other issue everyone is trying to get across is that the scanlines of the lower field will be drawn in the wrong place (shifted up by one scan line) if you simply separate the fields. Hence the suggestions to bob deinterlace into 50 frames per second and resize. But with 1080i video the one scan line vertical shift may not be very visible most of the time.
    Quote Quote  
  20. Originally Posted by manono View Post
    The numbers (23.976, 29.97, 59.94, 25, even 50, they all traditionally refer to the FramesPS. Why all of a sudden do people decide a number refers to FieldsPS?


    It's been gradual transition, but officially , in most editing software it's almost universally labelled "50i" now . As suggested above, I think it really was a marketing push that drove the transition. Marketing always wins ... look at Apple

    Some "official" governing bodies like ATSC, STMPE, blu-ray consortium also use this nomenclature of using the field rate to express interlaced formats instead of the frame rate . I think EBU still expresses as frame rate "25i"

    OT: it's just like PAR used to indicate pixel aspect ratio back in the MPEG2 days, but now it's called officially SAR or sample aspect ratio by the MPEG4 group (including AVC/h.264, blu-ray) . There's bound to be more "switcharoos" in the future
    Quote Quote  
  21. Member
    Join Date
    Dec 2012
    Location
    Romania, Europe
    Search Comp PM
    Ok, let's not argue about all those terms. I know very well what 50i means. The only new information you guys told me, was about that offset of the second frame, and i got it from the beginning, and I thank you for that. All other posts about names and marketing are offtopic.

    So, in conclusion, I understand that my initial idea is not usable in practice.
    Quote Quote  
  22. Originally Posted by omepheus View Post
    So, in conclusion, I understand that my initial idea is not usable in practice.
    Why don't you just try it and see. Like I said, with 1080i video an offset of 1 scan line is not very visible unless you have very sharp (which usually means computer generated) material.
    Quote Quote  



Similar Threads

Visit our sponsor! Try DVDFab and backup Blu-rays!