Developer Notes

Likely resolved by the fix for UE-16027

Description

Using the same import settings in UE4.8 and UE4.9 will result in a different number of frames of an animation being imported from the same FBX file.

If you import the same fbx animation which in Maya is between 0-29 (@30fps):

in 4.8.3 : the value of NumFrame of the UAnimSequence will be 30 and sequenceLength = 0.96666s
in 4.9 : the value of NumFrame of the UAnimSequence will be 29 and sequenceLength = 0.96666s

It's like NumFrames represented the number of keys in 4.8 and now it represents the number of intervals.

Steps to Reproduce

1. Launch any Blueprint project in UE4.8.3
2. Create a blank Test directory
3. Import the attached "A_FrameRate_Test" FBX using the same settings as the attached image, "48_ImportSettings.png"
*Primary animation settings: "Animation Length: Exported Time" and "Use Default Sample Rate" checked
4.NOTE: that the resulting value of NumFrame of the UAnimSequence will be 30 and sequenceLength = 0.96666s *See Image,"48_Results.png"
5. Now launch any Blueprint project in UE4.9
6. Create a blank Test directory
7. Import the attached "A_FrameRate_Test" FBX using the same settings as the attached image, "49_ImportSettings.png"
*Primary animation settings: "Animation Length: Exported Time" and "Use Default Sample Rate" checked
8. NOTE: that the resulting value of NumFrame of the UAnimSequence will be 29 and sequenceLength = 0.96666s *See Image,"49_Results.png"
RESULT: A difference in the number of frames is generated from the same FBX file between UE4.8.3 and UE4.9
EXPECTED: No difference in the number of frames generated from the same FBX file between UE4.8.3 and UE4.9

Have Comments or More Details?

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Cannot Reproduce
ComponentOLD - Anim
Affects Versions4.9
Target Fix4.13
CreatedSep 14, 2015
ResolvedJul 21, 2016
UpdatedMay 18, 2020