demux: mp4: refine sync sample using rap group (refs #16732)
demux: mp4: refine sync sample using rap group (refs #16732)

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc