Mediaconvert Frame Rate follow source inserts frames on the output when audio video duration mismatches.

AWS MediaConvert will transcode a file until it is completely consumed. If the audio in a file is longer than the video, MediaConvert will continue encoding until the audio is finished.

The Frame Rate used by MediaConvert is the frames per second created on the output of the transcode. If not set, MediaConvert will default to using the source file Frame Rate, which in your file is 24fps.

The difference between 116.029s and 115.907s is .122s. If the source frame rate is constant, using 24fps, that would be about 8.318 frames. Having a source file that has audio ending with the video may simplify your issue.

You may want to review the following links on MediaConvert outputs and frame rates. https://docs.aws.amazon.com/mediaconvert/latest/ug/working-with-video-frame-rates.html https://docs.aws.amazon.com/mediaconvert/latest/ug/using-variable-frame-rate-inputs.html