David Esp Video Technical Blog

I came across some old videos I shot on a Nokia N95 and pulled these into Adobe Premiere.  However the individual video clips were each listed with a different framerate, hovering vaguely around 29 fps (27.08 up to 29.45).   Questions:

• What does that even mean?
  • From web-search, it sounds like it’s an average, and N95 framerates within a given recording can vary wildly
    • e.g. between 6 and 38 fps.
• How do various apps etc. handle such material?
  • YouTube:
    • In 2009 at least, it sounds like YouTube went for the minimum fps in any such clip.
  • Adobe Premiere
    • Seems to go for the average
      • I dragged a N95 clip on the “New Sequence” button and the resulting sequence had the clip’s average framerate.
    • Presumably just duplicates/drops frames as required to maintain the Sequence’s framerate.
  • GSpot (video analyzer):
    • For a clip reported by Adobe Premiere to be 28.81 fps, GSpot reported it to be 29.412 fps.
      • Misleading info from one or other or both…

Web-search:

• Bing:[nokia n95 video frame rate variable]
  • http://www.allaboutsymbian.com/features/item/Nokia_and_Mac-working_beautifully.php
    • With variable frame rates, these have traditionally caused problems on most PC video editors, with audio/video sync issues.
    • YouTube may not know what to make of that variable frame rate, so they may opt to cut the frame rate down across the board?
  • http://www.google.com/support/forum/p/youtube/thread?tid=50c2a207bd043911&hl=en&fid=50c2a207bd04391100046fb9993e3c6a
    • The original is absolutely smooth, recorded 25 fps on my Nokia N95, transferred to my computer and then straight to YouTube – not a single edit. It plays very smoothly on both my phone and in VLC, so why is it so bad on Youtube?
    • The one thing that jumps right out at me is that variable frame rate.
      • Frame rate mode                  : Variable
        Frame rate                       : 29.454 fps
        Minimum frame rate               : 5.856 fps
        Maximum frame rate               : 38.462 fps
      • Not sure why that is, but it certainly could be the cause of a much lower frame rate in some spots, and it might have thrown the encoders for a loop.
  • http://premierepro.wikia.com/wiki/FAQ:Does_Premiere_Pro_support_variable_frame_rates_on_P2%3F
    • Q: Does Premiere Pro support variable frame rates on P2?
    • A: Yes – any VFR clip will import as a 60 fps (or 50 fps for PAL countries) clip, but the framerate will be what is set on the camera. ie, if you shot 18 fps, you’ll get an 18 fps cadence within a 60 fps file.
      • {Does that mean each of the 18fps-shot frames gets to appear 1/60 of a second?}

This entry was posted on Thursday, January 19th, 2012 at 20:21 and is filed under Adobe, cellphone, Premiere, YouTube. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.