Add a test program where looping in trick mode works seamlessly

The secret here is to use SEGMENT seeks instead of normal seeks:
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstEvent.html#GstSeekFlags

That has been tested with positive playback rates only.

diff --git a/gst-trick-mode-looping-3.py b/gst-trick-mode-looping-3.py
new file mode 100755 (executable)
index 0000000..94b99af
--- /dev/null
+++ b/gst-trick-mode-looping-3.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python
+
+# Get a test sample with:
+# youtube-dl -t http://www.youtube.com/watch?v=yWa-YXiSk2Y
+
+import sys
+
+import gobject
+gobject.threads_init()
+
+import gst
+
+
+class Player:
+    def __init__(self, filename, rate):
+        self._filename = filename
+        self._rate = rate
+
+        self._player = gst.element_factory_make("playbin2", "player")
+        self._player.set_property("uri", filename)
+
+        bus = self._player.get_bus()
+        bus.add_signal_watch()
+        bus.connect('message::state-changed', self.on_state_changed)
+        bus.connect('message::segment-done', self.on_segment_done)
+
+    def run(self):
+        self._player.set_state(gst.STATE_PLAYING)
+        loop = gobject.MainLoop()
+        loop.run()
+
+    def on_segment_done(self, bus, msg):
+        self._player.seek(self._rate, gst.FORMAT_TIME,
+                gst.SEEK_FLAG_SEGMENT | gst.SEEK_FLAG_SKIP | gst.SEEK_FLAG_ACCURATE,
+                gst.SEEK_TYPE_SET, 0,
+                gst.SEEK_TYPE_END, 0)
+
+    def on_state_changed(self, bus, msg):
+        if msg.src != self._player:
+            return
+
+        print 'on_state_changed'
+        old_state, new_state, pending = msg.parse_state_changed()
+        print "%s -> %s" % (old_state, new_state)
+        if old_state == gst.STATE_READY and new_state == gst.STATE_PAUSED:
+            self.set_rate(self._rate)
+
+    def set_rate(self, rate):
+        self._rate = rate
+
+        if rate == 0:
+            self._player.set_state(gst.STATE_PAUSED)
+        else:
+            self._player.set_state(gst.STATE_PLAYING)
+            self._player.seek(self._rate, gst.FORMAT_TIME,
+                    gst.SEEK_FLAG_SEGMENT | gst.SEEK_FLAG_SKIP | gst.SEEK_FLAG_FLUSH | gst.SEEK_FLAG_ACCURATE,
+                    gst.SEEK_TYPE_SET, 0,
+                    gst.SEEK_TYPE_END, 0)
+
+
+def main(args):
+    def usage():
+        sys.stdout.write("usage: %s <URI-OF-MEDIA-FILE>\n" % args[0])
+
+    if len(args) != 2:
+        usage()
+        sys.exit(1)
+
+    if not gst.uri_is_valid(args[1]):
+        sys.stderr.write("Error: Invalid URI: %s\n" % args[1])
+        sys.exit(1)
+
+    player = Player(args[1], 3.0)
+    player.run()
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))