subparse : need_segment flag was set too early

Submitted by Mingke Wang

Link to original bug (#747498)

Description

Created attachment 301118
set need_segment after sink pad received GST_EVENT_SEGMENT

subparse works in push mode, chain funciton will be called once up stream element finished the seeking and flushing. if set need_segment flag in src pad event handler, the segment event will be pushed earlier, result in the subtitle text will
be send out to down stream from the beginning. if the text sink (such as using appsink to catch text) don't compare the video timestamp with the received text timestamp, then the text and video will not sync.

Patch 301118, "set need_segment after sink pad received GST_EVENT_SEGMENT":
0004-subparse-set-need_segment-after-sink-pad-received-GS.patch

Version: 1.4.5