Question about frame rates?

Discussion in 'DivX / XviD' started by erik1213, Mar 1, 2004.

  1. erik1213

    erik1213 Regular member

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    If the same video is encoded at 2 different frame rates, then will the length of the videos differ? I tried this by playing them both from the beginning at the same time and for some reason the shorter movie always ends up ahead, in time, of the other movie. They both have the same exact beginning (no parts missing) so i can't understand why?

    Because that's what I have except they're from 2 different sources ( i downloaded them). But they're the same movie. The only other thing I can think of is that in the shorter movie there are some parts of the movie missing.


    Can Anyone Please Help?
    Thank You!!!
     
  2. vurbal

    vurbal Administrator Staff Member

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    What are the framerates of the 2 movies? If one is PAL and the other is NTSC that could explain it. NTSC DVDs from film sources are encoded at 23.976fps progressive because this framerate is almost identical to the original film (24fps) and can be easily converted to NTSC video (29.97fps) by a player. Since the PAL standard uses 25fps instead of 29.97fps it's possible to encode a film in PAL without adding frames by just speeding up the movie by 1fps (from 24 to 25). That makes them a little shorter than the NTSC version. If one is 23.976fps and the other is 25fps that's probably the difference.
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    Last edited: Mar 1, 2004
  3. erik1213

    erik1213 Regular member

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    Well it started out as an XviD(Shorter film) file and a DVD movie file which i converted to DivX(longer film). They are both 25fps. Could the converting have slowed it down?
     
  4. vurbal

    vurbal Administrator Staff Member

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    You'll have to be more specific about the movies. I'm confused about what you have. This is your initial question:
    Now you say:
    So where is the different framerate? Are you saying that you started with an Xvid file, converted it to DVD, and then encoded to Divx from the DVD you made? Also, are you in PAL-land or NTSC-land?
     
  5. erik1213

    erik1213 Regular member

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    OK, I have the same movie downloaded from 2 different sources. One was a DVD type file I downloaded and the other was an XviD. The length of the DVD is 10 min longer than thee length of the XviD. I'm wondering that if the DVD could be slower than the XviD in the frame rates and that is why it is 10 min longer(otherwise there are missing scenes in the XviD file). Because when I play the 2 movies at the at the same time, starting from the same point in the movie(the begnning where i know there are no scenes missing and they are the exact same) the XviD file always ends up ahead of the DVD file(even if i start the DVD first...wait a min then start the XviD).


    The part where I said they are both 25fps I mean after I converted the DVD to DivX they both(Divx and XviD) read as 25fps. I can't tell what the fps in a DVD is cause i dunno how...lol.


    Sorry if I am confusing you. I don't really know how to explain it. Thank You for your help!
     
  6. vurbal

    vurbal Administrator Staff Member

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    No problem about the confusion. Everybody has to start somewhere. ;)

    Just to make sure I'm clear about everything now. From what you're saying, the DVD was already 10 minutes longer than the Xvid and the Divx is the same length as the DVD. If that's the case the DVD should be the same framerate as the Divx.

    If you want to figure out why the Divx file is longer than the Xvid, you could load each of them in VirtualDub to compare. You should open up 2 VirtualDub windows to compare them side by side. I'd start out by looking at the file information (from the File menu select File Information) to compare the number of frames and total time. You can also use VirtualDub to navigate through the files one frame at a time (or several frames at a time) to find out if they have the same pictures at the same frames.

    If the first 50 frames are the same, try going to a spot in the middle and comparing frames between the 2. You can use Go To from the Edit menu to navigate directly to the frames you want to look at.
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    Last edited: Mar 2, 2004

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