25fps AVI to NTSC DVD

Discussion in 'Other video questions' started by max777, Jul 30, 2004.

  1. max777

    max777 Member

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    My conversion from a 25fps AVI to MPEG is choppy/freezes, and my bet is that it did not convert it correctly. I need it in NTSC. I can't use PAL.

    I'm using Mainconcept MPEG Encoder right now and there doesn't seem to be an easy way to go from 25 to 29.97 or 23.976 3/2 pulldown. What do I need to do?
     
  2. Minion

    Minion Senior member

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    Do you know how to use AVISynth???

    AVISynth is one of the Best Video Tools available but it is Difficult to use because it uses a Scripting Language to implement it"s Functions and it"s Filters..

    With the Proper AVISYnth script you can use it to Slow the Frame rate of your 25fps Pal file to 23.976fps and then you would just have to add 3:2 Pulldown flags to make it 29.976fps NTSC....

    So basicly all you need to do is install the AVISynth.dll file on your PC and then write a Script like this:

    AVISource("C:\My File.avi")
    AssumeFPS("23.976,True")

    so just Install AVISynth then Just write that on Notepad and save it as a File with an .avs extention and then Load it into the MainConcept Encoder and encode it like normal but make sure you add the 2:3 pulldown flags in the mainconcept settings or you can encode it to 23.976fps and then use a Program Like "DoPulldown" to add the 3:2 Pulldown flags....

    You can also use AVISynth to Resize the Image and clean up Noise and sharpen the Image and many other things if you have the Right filters installed and know the Scripting commands....

    You can read up on AVISynth over at "http://www.avisynth.org/"...

    Cheers
     
  3. max777

    max777 Member

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    Thanks for the great info! What happened is I stepped away from burning DVD's, and came back to find I forgot what I was doing. lol! I'm able to convert to 29.97 just fine without any extra steps, so I'm good to go. But I still need to look into why 23.976 3/2 pulldown is giving me crazy skipping. It might boost my image quality to encode in a lower framerate if the source is low to begin with.
     
  4. Minion

    Minion Senior member

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    Encoders Like MainConcept encoder and Tmpgenc and basicly any other encoder can not do proper Frame Rate Conversions...
    What they do is Delete or Duplicate frames to make up the New Frame rate which is what causes the Skipping effect....With Pal 25fps File the Proper way to convert them to NTSC is to Slow the Video down to 23.976fps and then add 3:2 Pulldown Flags to make it 29.976fps, but most encoders will just duplicate every Fifth frame to make 25fps into 29.976fps which causes a Skipping effect in high action scenes because you are looking at duplicated frames.....

    well good Luck
     
  5. max777

    max777 Member

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    Hey Minion, just tried avisynth and looks like that did the trick. Amazing that I've been converting 24fps AVI's to NTSC DVD all this time with that slight stutter and not realizing it. All I had to do was make that script and drag and drop it into my MPEG encoder (which is setting the 3:2 on the fly).

    The only thing is, avisynth does not seem to handle AC3. I'll have to make a full run and see how bad it gets out of synch. lol! It's only a "24fps" to "23.976" conversion.

    Thanks for the tip!

    _X_X_X_X_X_[small]Jason Honingford
    Web Developer / Designer
    http://www.framescale.com
    Florida, US[/small]
     
    Last edited: Aug 9, 2004
  6. Minion

    Minion Senior member

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    If you use this AVISynth Command:

    AssumeFPS(23.976,True)

    Then AVISynth will slow the Framerate down to 23.976fps and Dynamicly resample the audio so it is also slower down and in Perfect sync...

    There are also a Bunch of great Noise filters in AVISynth that are great for Clearing up Video that is a Little Noisy....

    Cheers
     
  7. max777

    max777 Member

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    Sorry I just edited my post, you think I can just use virtual dub or something to reduce the AC3?
     
  8. Minion

    Minion Senior member

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    You can load in the AC3 if you the AC3 Import Filter in AVISynth or what is better is of you use this simple tool I have that will turn the AVI with AC3 audio to an AVI with Uncompressed audio that AVISynth can handle...
    If you PM me with your Email address I can send you this tool....

    Cheers
     

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