Please describe the problem:
Rtspsrc implements `seek' feature by sending a `PLAY' method with a `Range' header. When I play the rtsp movie in m.youtube.com, I find out the range header in youtube server's reponse doesn't match the range which we requested. For example, If rtspsrc sends a PLAY method like this:

==========================================================
RTSP request message 0xbfff6820
 request line:
   method: 'PLAY'
   uri:    'rtsp://bfug.rtsp-youtube.l.google.com/CkYLENy73wIaPQkbtZ8lPb6RIxMYDSANFEIJbXYtZ29vZ2xlSARSBWluZGV4Wg5DbGlja1RodW1ibmFpbGDGp_3r57jP7WMM/0/0/0/video.3gp'
   version: '1.0'
 headers:
   key: 'Range', value: 'npt=23.577449-'
 body:
RTSP response message 0xbfff6804
 status line:
   code:   '200'
   reason: 'OK'
   version: '1.0'
 headers:
   key: 'Session', value: '3f48abf7;timeout=90'
   key: 'Range', value: 'npt=21.666-32.100'
   key: 'RTP-Info', value: 'url=rtsp://bfug.rtsp-youtube.l.google.com/CkILENy73wIaOQkbtZ8lPb6RIxMYDSANFEIJbXYtZ29vZ2xlSARSBWluZGV4Wg5DbGlja1RodW1ibmFpbGDGp_3rBww=/0/0/0/video.3gp/trackID=0;seq=33714;rtptime=81371322,url=rtsp://bfug.rtsp-youtube.l.google.com/CkILENy73wIaOQkbtZ8lPb6RIxMYDSANFEIJbXYtZ29vZ2xlSARSBWluZGV4Wg5DbGlja1RodW1ibmFpbGDGp_3rBww=/0/0/0/video.3gp/trackID=1;seq=3724;rtptime=46395124'
   key: 'CSeq', value: '8'
   key: 'Server', value: 'Google RTSP 1.0'
 body: length 0
==========================================================

We requested a play range: npt=23.577449-, but the response is: npt=21.666-32.100. OK, when the rtspsrc sent the PLAY method, it will parse the response. The function `gst_rtspsrc_parse_range' handles the `range' part.This function will separate the min and max value in range and call `gst_segment_set_last_stop' to update the segment's last_stop field using the min value.

The interest part is in `gst_segment_set_last_stop'. This function updates the segment's last_stop field in this way:

segment->last_stop = MAX (segment->start, position);

segment->start is 23.57749, and the position is 21.666. So, the result is the segment's last_stop is 23.57749 while not 21.666.

After parsing the response finished, rtspsrc will call the function `gst_rtspsrc_configure_caps' and the GstRtpBaseDepayload will send the newsegment event according to this caps. This will make the newsegment has a WRONG npt-start value. And this will also cause the POSITION query returns a wrong value. In my rtsp-player, I noticed that when the progress bar exceeds 100%, the movie is still playing.


Steps to reproduce:
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Actual results:


Expected results:


Does this happen every time?
Yes

Other information:
We should set the segment's last_stop to the value youtube server gives. So we can set the last_stop directly, not calling the `gst_segment_set_last_stop'.