Currently testing .ass subcaps in a VFX workflow. The goal is to drop specfic text over specific shots and the in/out points have to be frame accurate We're working in a 23.976 project. Currently having no trouble using FFmpeg to generate frame-accurate subclips of individual shots from a full-show export by converting hh:mm:ss:ff to seconds and then handling the 24 to 23.976 offset, using the following alorithm: InPoint_Seconds = ConvertToSeconds(InPoint_Hmsf_FullShow) - ConvertToSeconds(Start_Hmsf_FullShow) // Convert from SMTPE Time Code to seconds. InPoint_Seconds = InPoint_Seconds * (1001 / 1000) //Handle 24 to 23.976 offset OutPoint_Seconds = [Same idea as above] Duration_Seconds = Output_Seconds - InPoint_Seconds > ffmpeg -ss InPoint_Seconds -t Duration_Seconds -i SourcePath -c copy DestPath So generating frame-accurate copies of portions of a larger file works with perfect accuracy BUT when applying the same logic to subcaps using .ass files, sometimes they land with frame accuracy, and sometimes they don't (They'll be 1 frame late at most, and it does not increase over the span of the source clip). Curious if anyone has any ideas. - Chris C