Adaptivedemux : adaptive stream REW problem

there are REW issues when playback fragmented MP4 files with mpd file.

issue No.1 : during REW, sometimes playtime increases by 1 second and decreases.

solution : in case of REW, didn't set segment base time.

issue No.2 : if recorded file has two or more periods, REW stopped.

solution : when update streams segment, if segment start time is less than period start time, Do not subtract period start time from segment start time.

issue No.3 : if pause at playtime 0 sec and do REW, playback is stopped.

solution : in case of REW, if download loop function handle EOS, playback is stopped by download fail error handling. the fragment download function will handle the EOS of REW.