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  1. Member
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    I'm trying to reduce some captures that come in at 60fps. I did one to 23.976 using tmpgenc video mastering works and the result is choppy/jerky video. I'm not even sure what setting I would tweak or what other options I'd have.

    Any suggestions that I can at least translate to vmw if not in it directly?
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  2. Member Cornucopia's Avatar
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    If the captures are capturing motion & unique frames at each time instance, you can never achieve NO loss of smoothness, unless the amount or type of motion is lower than a reduced capture rate (and changes occur in sync with that rate).
    IOW, if you move slowly enough a lower framerate would still be able to handle it.

    However, "stuttery" refers not just to low speed but to UNEVEN framerates. Framerate reduction that is whole numbered is much smoother than framrate reduction that has a cadence. Stairsteps that are uneven are much more noticeable than just bigger stairsteps.

    What you seemed to do in your example was a form of IVTC, which sets up a cadence (usually 3:2:3:2). TC usually goes from 24->30, and IVTC usually removes that cadence and restores the original 24fps, but since your original was 60fps, there was no original to restore and so you are Generating a cadence through decimation.

    Try doing whole multiple rate reduction: 60->30 (2:1), with or without frame blending. It takes out every other frame, but the result is still "natural" motion.

    Scott
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  3. Member Bernix's Avatar
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    Check correct framerate of your source video. If is it 60fps or 59.94
    Best practice is get framerate divided by 2. Which of course 23,976 isn't. So try to do it to 30fps if 60fps or 29,97fps if 59,94.
    You should get better result.

    Scott was faster

    Bernix
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    Originally Posted by Bernix View Post
    Check correct framerate of your source video. If is it 60fps or 59.94
    Mediainfo confirms 60fps

    Originally Posted by Cornucopia View Post
    Try doing whole multiple rate reduction: 60->30 (2:1), with or without frame blending. It takes out every other frame, but the result is still "natural" motion.
    Thanks guys - I'll give 30 a shot and see what kind of issues I have there...
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  5. You can add some motion blur and you can go to interlaced... eventually you may try to perform framerate conversion with motion interpolation/compensation
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    Originally Posted by pandy View Post
    You can add some motion blur and you can go to interlaced... eventually you may try to perform framerate conversion with motion interpolation/compensation
    I'm game - but how would I do that?
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  7. Why do you lower frame rate?
    I'm asking because you reduce it to 23.976 now trying 30fps, so it seams that you do not have a project or mixing editing problem.
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  8. Originally Posted by doncaruana View Post
    Originally Posted by pandy View Post
    You can add some motion blur and you can go to interlaced... eventually you may try to perform framerate conversion with motion interpolation/compensation
    I'm game - but how would I do that?
    Video editor- even free offer such video processing - less choppy motion can be if your frame rate will be half of source. It is not clear to me what is your goal - perhaps there is other way to achieve result without sacrificing frame rate.
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    Originally Posted by pandy View Post
    Originally Posted by doncaruana View Post
    Originally Posted by pandy View Post
    You can add some motion blur and you can go to interlaced... eventually you may try to perform framerate conversion with motion interpolation/compensation
    I'm game - but how would I do that?
    Video editor- even free offer such video processing - less choppy motion can be if your frame rate will be half of source. It is not clear to me what is your goal - perhaps there is other way to achieve result without sacrificing frame rate.
    I want to reduce the size and I want it to play well on a TV.
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  10. Reducing frame rate 50% would not reduce video size 50%. It does not work like that, if you planned on this sort of rule. Frames are suddenly "further apart" so changes are bigger, so more bits have to allocated as oppose using double frame rate.

    If it is captured video, like games , are you using CRF method for encoding? That might surprise you how effective it could be for that kind of video, meaning you might end up with much lower average as oppose guessing it using 2pass VBR or just 1pass bitrate encoding.

    If video is not much dynamic at all, you might benefit reducing frame rate, but do not blend, interpolate frames or anything, just skip every other frame with whatever software or videoeditor you use.

    So basically it helps if you say what are you actually doing, what are you capturing etc. Otherwise it is a bunch of folks telling you something and shooting in the dark general rules at you.
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    Originally Posted by _Al_ View Post
    Reducing frame rate 50% would not reduce video size 50%. It does not work like that, if you planned on this sort of rule. Frames are suddenly "further apart" so changes are bigger, so more bits have to allocated as oppose using double frame rate.
    I never said or thought cutting frames in half would cut the size in half. But reducing the frames per second will help. The source is at 60 but I would rather capture at that rate and then use processing to handle the rest.

    Originally Posted by _Al_ View Post
    If it is captured video, like games , are you using CRF method for encoding? That might surprise you how effective it could be for that kind of video, meaning you might end up with much lower average as oppose guessing it using 2pass VBR or just 1pass bitrate encoding.
    It is a capture from TV and I'm using constant quality.
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  12. Member Cornucopia's Avatar
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    If it's a capture from (US) TV, then very likely it should either have been 1280x720@60p (or 59.94p), where you should keep the high framerate because those shows usually have higher motion, or it should have been 1920x1080@60i (59.94i), where it is already interlaced and dropping the framerate should be done only when absolutely necessary and only using smart deint tools. ATSC currently doesn't support 1080p60.

    If you captured some other way, you MAY have duplicate frames or inherent judder, depending.

    Scott
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  13. Originally Posted by doncaruana View Post
    I want to reduce the size and I want it to play well on a TV.
    Then depends on your TV set and go for 1080p60 or 720p60, apply some antialiasing processing, IMHO some blur may help, use crf mode and level compliant with your TV decoder capabilities (i.e. at least 4.0 for 30p and at least 4.2 for 1080p60), favour also slower processing than fast.

    https://software.intel.com/en-us/articles/common-bitrate-control-methods-in-intel-media-sdk
    https://software.intel.com/en-us/articles/advanced-bitrate-control-methods-in-intel-media-sdk

    Reducing bitrate by frame rate conversion is most significant quality degradation.
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    Part of the problem for me is I don't know where or how to do some of the things mentioned in this thread, especially with video mastering works, which is what I'm using.

    However, it sounds like the recommendation, at least in my case, is to just go to 30fps and, in general, the best bet is to keep to simple math if converting frame rates.

    As an FYI, transcoding a sample video made a difference of about 12% in going to 23.976 vs 30fps for me, where the 30fps was larger.
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