diff --git a/ChangeLog b/ChangeLog
index 15046c5933..f50c3a9032 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2007-09-11  Wim Taymans  <wim.taymans@gmail.com>
+
+	* docs/design/part-live-source.txt:
+	Add docs on how live sources should timestamp.
+
+	* libs/gst/base/gstbasesrc.c: (gst_base_src_do_sync):
+	Add some more debug info.
+	For subclasses that are live and like to sync, add aditional startup
+	latency to sync time and timestamps so that we timstamp according to the
+	design doc.
+
 2007-09-11  Tim-Philipp Müller  <tim at centricular dot net>
 
 	* gst/gstbuffer.c:
diff --git a/docs/design/part-live-source.txt b/docs/design/part-live-source.txt
index 59691334fe..0e472ffa02 100644
--- a/docs/design/part-live-source.txt
+++ b/docs/design/part-live-source.txt
@@ -46,3 +46,15 @@ The latency is the time it takes to construct one buffer of data. This latency
 is exposed with a LATENCY query.
 
 See part-latency.txt.
+
+
+Timestamps
+----------
+
+Live sources always timestamp their buffers with the running_time of the
+pipeline. This is needed to be able to match the timestamps of different live
+sources in order to synchronize them.
+
+This is in contrast to non-live sources, which timestamp their buffers starting
+from running_time 0.
+
diff --git a/libs/gst/base/gstbasesrc.c b/libs/gst/base/gstbasesrc.c
index 043285590d..275eeeb431 100644
--- a/libs/gst/base/gstbasesrc.c
+++ b/libs/gst/base/gstbasesrc.c
@@ -1507,6 +1507,9 @@ gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
   if (basesrc->priv->startup_latency == -1) {
     now = gst_clock_get_time (clock);
 
+    GST_LOG_OBJECT (basesrc, "startup timestamp: %" GST_TIME_FORMAT,
+        GST_TIME_ARGS (timestamp));
+
     /* startup latency is the diff between when we went to PLAYING (base_time)
      * and the current clock time */
     if (now > base_time)
@@ -1514,7 +1517,7 @@ gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
     else
       basesrc->priv->startup_latency = 0;
 
-    GST_LOG_OBJECT (basesrc, "startup latency: %" GST_TIME_FORMAT,
+    GST_LOG_OBJECT (basesrc, "startup running_time: %" GST_TIME_FORMAT,
         GST_TIME_ARGS (basesrc->priv->startup_latency));
 
     if (!GST_CLOCK_TIME_IS_VALID (timestamp)) {
@@ -1524,6 +1527,9 @@ gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
         timestamp = 0;
 
       GST_BUFFER_TIMESTAMP (buffer) = timestamp;
+
+      GST_LOG_OBJECT (basesrc, "created timestamp: %" GST_TIME_FORMAT,
+          GST_TIME_ARGS (timestamp));
     }
 
     /* we have a timestamp, we can subtract it from the startup_latency when it is
@@ -1534,6 +1540,9 @@ gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
       else
         basesrc->priv->startup_latency = 0;
     }
+
+    GST_LOG_OBJECT (basesrc, "startup latency: %" GST_TIME_FORMAT,
+        GST_TIME_ARGS (basesrc->priv->startup_latency));
   } else {
     /* not the first buffer, the timestamp is the diff between the clock and
      * base_time */
@@ -1548,6 +1557,16 @@ gst_base_src_do_sync (GstBaseSrc * basesrc, GstBuffer * buffer)
   if (!GST_CLOCK_TIME_IS_VALID (start))
     goto invalid_start;
 
+  if (basesrc->is_live) {
+    /* live source and we need to sync, add startup latency to timestamp to
+     * get the real running_time */
+    if (timestamp != -1) {
+      start += basesrc->priv->startup_latency;
+      GST_BUFFER_TIMESTAMP (buffer) =
+          timestamp + basesrc->priv->startup_latency;
+    }
+  }
+
   GST_LOG_OBJECT (basesrc,
       "waiting for clock, base time %" GST_TIME_FORMAT
       ", stream_start %" GST_TIME_FORMAT,