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A
A.I.1
Legend
January 16, 2018
Answered

Editing & Rendering 29.970 footage

  • January 16, 2018
  • 1 reply
  • 1493 views

I was given a video (.mp4 file, mpeg4/AVC) that was 29.97fps (exactly). Media Info says Frame Rate 29.970 (29970/1000) FPS.

29970/1000=29.97 exactly.

I created a new composition from that video in After Effects CC 2017, rendered the video with Adobe Media Encoder CC 2017, with the H264 codec as a .mp4, with "Match Frame Rate" selected, and AME rendered the video and Media Info says the Frame Rate of the rendered video is 29.970 (30000/1001) FPS.

30000/1001=29.97002997002997....

So again this is another problem with AME only allowing a limited amount of frame rates and not matching the source frame rate.

I suppose I'd have to render it as a .mov to actually match the source frame rate?

I created the composition in After Effects from the source video file, but AE only shows the frame rate as "29.97" (it doesn't say whether it's 29.97 exactly or 29.97002997002997..) - how do I tell which it is?

Will AME ever be changed to be able to match the source frame rates that aren't in the list (such as exactly 29.97 fps)?

What duration would the video need to be for there to actually be a difference between 29.97 and 29.97002997002997.. (ie. how many seconds/mins etc. long would the video need to be for it to make a difference)? edit: I assume it would depend on what device it is being played on - I assume it's being played mostly on "60Hz" computer screens.

This topic has been closed for replies.
Correct answer SAFEHARBOR11

Thanks. Though I was using Adobe Media Encoder to render a video composition of a video edited in Adobe After Effects (CC 2017).

Maybe you're right and there's no real difference (though I assume it will make about a frame of difference every so often - which may show as an occasional repeated frame or dropped frame). But maybe any difference is only applicable to long clips and it was a clip around 8.5 secs so maybe the short length of the video will mean the difference is not likely to have any affect (though may have a tiny affect if the clip is part of a bigger video).

In After Effects CC2017 there's "Interpret Footage" and for frame rate it says I can either "Use frame rate from file (29.970)" or "conform to frame rate" (and it has 29.97 in that box). My guess is if I selected "conform to frame rate 29.97" it would still actually use not exactly 29.97 (ie. I guess it would use 29.97002997002997...) since I assume it would assume you mean that because it's a common frame rate (though I suppose I could try it).

Maybe the client won't mind that it doesn't seem to be exactly the same frame rate as his source video. I'm just wondering how I can fix it if he (or a difference client) asks for it to be kept (exactly) the same. Though maybe most people won't mind the tiny percent difference, particularly on short videos.


I'm maintaining that there is nothing to fix and this is much ado about nothing

1 reply

S
SAFEHARBOR11
Participating Frequently
January 16, 2018

I think you are overthinking a problem that is not there. We're talking about 2/100,000 difference...and in fact that is probably just the way the program is reporting it and there is likely no actual difference between the two frame rates. So manually set export frame rate to 29.97 exactly if it provides peace of mind to you.

Thanks

Jeff

    A
    A.I.1Author
    Legend
    January 16, 2018

    I think you are overthinking a problem that is not there. We're talking about 2/100,000 difference.

    Thanks.

    So manually set export frame rate to 29.97 exactly if it provides peace of mind to you.

    How would I do that in Adobe Media Encoder (CC 2017)? When encoding to h264 (.mp4) and uncheck "match source" for frame rate, I can't enter a value for the frame rate - it only lets me select it from a list (ie. ...25, 29.97, 30, ...).

    If I select "quicktime" (.mov) as the format and "h264" codec, and unselect the "match source" for frame rate, it again only lets me select a frame rate from a list (ie. ...25, 29.97, 30, ...) rather than typing a value for the frame rate.

    Or did you mean to type it in the composition settings for After Effects, instead of creating the composition from the source video file (where it automatically puts a frame rate for the comp)?

    S
    SAFEHARBOR11
    Participating Frequently
    January 16, 2018

    I don't believe there is any difference whatsoever in what you are seeing reported, 29.97 is 29.97 and it should not be a concern.

    However, when using Match Source from Premiere Export and output parameters are "ghosted", just uncheck the check to the right of Frame Rate and you will get the drop down to choose.

    In reality, I don't even like using Match Source because it can have undesirable results. Rather, I will consider the destination/delivery method intended for the export and choose an appropriate preset, such as YouTube 1080p29.97 for instance.

    Thanks

    Jeff

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