<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi<div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>I already declare flip function in video.c and ibvlc_media_player.h. </div><div><br></div><div>the other way, I trace the Makefile in ./Project/Mozilla, I found the error is happen in the </div><div><font class="Apple-style-span" color="#A4A4A4" face="Monaco"><br></font></div><div><font class="Apple-style-span" face="Monaco" size="3"><span class="Apple-style-span" style="font-size: 12px;">npvlc.la: $(npvlc_la_OBJECTS) $(npvlc_la_DEPENDENCIES) </span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Monaco; "><span class="Apple-tab-span" style="white-space:pre"> </span>$(npvlc_la_LINK) $(am_npvlc_la_rpath) $(npvlc_la_OBJECTS) $(npvlc_la_LIBADD) $(LIBS)</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Monaco; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Monaco; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Monaco; "><span class="Apple-style-span" style="font-family: 'LiHei Pro'; font-size: medium; ">I still have no idea how to fix this error, thanks.</span></div></body></html>