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timestamps different between mp4 and TS_VIDEO folder

Discussion in 'Convert video to another format' started by eddified, Jan 16, 2015.

  1. eddified

    eddified Member

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    I have two copies of my video.

    One is the DVD clone (TS_VIDEO folder).
    The other is an h264/mp4 transcode made using handbrake of the entire TS_VIDEO folder.

    The total running length (according to VLC) is different by about 6 seconds. The video is approx 1.5 hrs. When I get to the same frame on both videos, the elapsed time is different. The elapsed time difference between the videos is different at various points in the movie. At one point the difference is 31 seconds. At first I didn't tweak any video encode settings, I used the defaults for "high profile". Then I re-encoded with "constant framerate" option. I've tried various settings, but the end result is the same: all hand-brake encoded vids have identical timestamps throughout the movie, but they all differ from the ones in the TS_VIDEO version of the vid.

    What's going on? Is this normal?
     
  2. Nepheler

    Nepheler Member

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    What frame rate did you use to transcode Video_TS to H.264 MP4?
     
  3. eddified

    eddified Member

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    Handbrake defaults (not sure what The number comes out to be.) I tried both "constant frame rate " and variable, same result.
     
  4. attar

    attar Senior member

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    I don't think the selected frame rate is relevant to the chapter marks.
    The chapters markers should (within a few frames or a second or two) should be the same time as the original DVD.
    I've found that different media players will display slightly different frames as the chapters are stepped through (even though they both indicate the same time) - but never approaching 30 seconds.
    Try posting at the VideoHelp site for more expert help.

    http://forum.videohelp.com/
     
  5. eddified

    eddified Member

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    The interesting thing is that the chapter markers look to be in the exact same place. That is to say, they appear to be on the same frame. The *only* thing different between the videos is the elapsed time displayed at the chapter markers. I'm wondering if it's a strange issue with VLC. Hm, I should try a different video player and see what happens.
     
  6. scorpNZ

    scorpNZ Active member

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    Sounds about right in that time stamps are different from dvd to vid format.If i'm not mistaken it happens because of the encoder used it drops unnecessary parts that were originally added to the movie or i could be thinking of something else as to why parts are dropped,however i am aware of it.
     
  7. attar

    attar Senior member

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    I have a tenous grasp of the technicalities, but you may be thinking of pulldown that's applied to film on an NTSC DVD.
    23.976 fps film is flagged to repeat every fourth frame so that during the faster playback (29.97) it reaches the same scene at the same time.
    If the DVD is converted to a format that doesn't use that form of signalling (soft pulldown?) and you tell the encoder you want to keep the original rate, then every four frames a copy of the frame is created by the encoder to keep the 29.97 frame rate.
    The effect can be seen if you load an NTSC DVD into VirtualDub.
    The number of frames displayed references the 29.97 playback, but if the IVTC filter is applied, the number of frames is reduced to reflect 23.976 fps.
    The running time doesn't change because although there are fewer frames they play back at a lower rate.
     

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