Original commit message from CVS:
2005-08-29  Andy Wingo  <wingo@pobox.com>

* ext/ogg/gstoggdemux.c (gst_ogg_demux_init): Init total_time to
-1.
(gst_ogg_demux_perform_seek): Clamp segment_stop only if it's
valid.
(gst_ogg_pad_submit_packet): Subtract the chain's begin_time only
if it's valid. Fixed streaming-mode playback.