docs: clarify clocks docs in manual

After a question on the mailing list, mention that *flushing* seeks reset the
running time.

diff --git a/docs/manual/advanced-clocks.xml b/docs/manual/advanced-clocks.xml
index 2ab1350bc34f4360a6577cea2a924625ba68a35e..dc2a756fbdd16e30e24b777e72d5eb5193752c1f 100644 (file)
--- a/docs/manual/advanced-clocks.xml
+++ b/docs/manual/advanced-clocks.xml
@@ -12,14 +12,16 @@
   </para>
   
   <para>
-    &GStreamer; derives several times from the clock and the playback state.
+    &GStreamer; derives several <emphasis>time value</emphasis> from the clock
+    and the playback state.
     It is important to note, that a  <emphasis>clock-time</emphasis> is
     monotonically rising, but the value itself is not meaningful.
     Subtracting the <emphasis>base-time</emphasis> yields the
     <emphasis>running-time</emphasis>. It is the same as the
     <emphasis>stream-time</emphasis> if one plays from start to end at original
     rate. The <emphasis>stream-time</emphasis> indicates the position in the
-    media.
+    media. The <emphasis>running-time</emphasis> is (re-)set to 0 when the 
+    pipeline starts to play and also after <emphasis>flushing</emphasis> seeks.
   </para>
 
   <figure float="1" id="chapter-clock-img">