Two-Pass v One-Pass Encodes for Frame Smoothness

Discussion in 'Apple TV and Home Theater' started by kolax, Sep 29, 2008.

  1. kolax macrumors G3

    Mar 20, 2007
    I know everyone recommends doing a Two-Pass on all video as it provides better quality, since the first pass, the encoder logs what frames need higher bit rates and other wonderful stuff.

    However, I always assumed Two-Pass was meant for fast moving frames, and provided smoothness rather than quality. This is something I've been Googling for a while, and haven't found an answer.

    Quality aside. Now picture this: I've recorded a Formula 1 race. Lots of movement, and particularly when the camera follows the cars round corners. Will doing a Two-Pass eliminate frame stutters?

    I use a typical 1000 kbps bitrate for all my encodes, and I see little quality difference between One-Pass and Two-Pass, and I can't actually see any improvement in smoothness of the frames which is what I'm more concerned about.
  2. dynaflash macrumors 68020

    Mar 27, 2003
    No. two pass does just what you found, it gives the encoder the advantage of having the stats file from the first pass to more appropriately dole out bitrate on the second pass. with current x264 in general the quality difference between single and two pass is an ever narrowing gap (which you note in your post).
    For what its worth, I rarely use two pass if ever. For me just not worth the extra encoding time. Its more likely that the "frame stutters" you are seeing is coming from a variable source framerate issue likely exacerbated by telecining or a variant thereof. Would need to know alot more about your source to say. But I think you will find that two pass encoding will not fix this problem.
  3. kolax thread starter macrumors G3

    Mar 20, 2007
    Thanks for the reply.

    I have a few TV recordings done using EyeTV software. When I playback these recordings in their original format using EyeTV, everything is quite smooth. However, when I export these, it isn't as smooth.

    I used HandBrake to do the encoding so I could have a much greater control over it all. Frame rate is 25fps.

    In EyeTV, the framerate says 50/25fps - so I'm using the exact same frame rate.

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