[FFmpeg-user] copyts with m4s segments

Hello, I'm trying to transcode MP4 segments from H.265 to H.264 -- .m4s files that each contain an, styp, moof, and mdat atom. The ftyp and moov atoms are in a separate init.mp4 file. However, the sequence number in the output mfhd atom, and the base media decode time in the output tfdt atom start from 0 with each .m4s. Is there a way to copy the sequence number and base media decode time from the input .m4s, and use the same timescales? I've tried the -copyts and -copytb flags, although they seem to have no effect. Thanks, Chris