More work on capsnego, mostly proxying

Original commit message from CVS:
More work on capsnego, mostly proxying
Added another testsuite for capsnego
Added caps to vorbisdec, mp3parse, mp1videoparse
Redid the queue proxy handling a bit.

gst/autoplug/gststaticautoplugrender.c

@@ -140,8 +140,8 @@ gst_autoplug_pads_autoplug_func (GstElement *src, GstPad *pad, GstElement *sink)
   GList *sinkpads;
   gboolean connected = FALSE;
 
-  GST_DEBUG (0,"gstpipeline: autoplug pad connect function for \"%s\" to \"%s\"\n",
-		  GST_ELEMENT_NAME(src), GST_ELEMENT_NAME(sink));
+  GST_DEBUG (0,"gstpipeline: autoplug pad connect function for %s %s:%s to \"%s\"\n",
+		  GST_ELEMENT_NAME (src), GST_DEBUG_PAD_NAME(pad), GST_ELEMENT_NAME(sink));
 
   sinkpads = gst_element_get_pad_list(sink);
   while (sinkpads) {

gst/gstpad.c

@@ -737,6 +737,12 @@ gst_pad_set_caps (GstPad *pad,
   g_return_val_if_fail (pad != NULL, FALSE);
   g_return_val_if_fail (GST_IS_REAL_PAD (pad), FALSE);		// NOTE this restriction
 
+  if (!gst_caps_check_compatibility (caps, gst_pad_get_padtemplate_caps (pad))) {
+    g_warning ("pad %s:%s tried to set caps incompatible with its padtemplate\n",
+		    GST_DEBUG_PAD_NAME (pad));
+    return FALSE;
+  }
+  
   GST_PAD_CAPS(pad) = caps;
 
   return gst_pad_renegotiate (pad);
@@ -920,6 +926,80 @@ cleanup:
   g_strfreev (split);
 }
 
+static gboolean
+gst_pad_renegotiate_func (GstPad *pad, GstPad *peerpad, GstCaps **newcaps, gint *counter)
+{
+  GstRealPad *currentpad, *otherpad;
+  GstPadNegotiateReturn result;
+  
+  g_return_val_if_fail (pad != NULL, FALSE);
+
+  currentpad = GST_PAD_REALIZE (pad);
+  otherpad = GST_REAL_PAD (peerpad);
+
+  GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiating pad %s:%s and %s:%s counter:%d\n",
+            GST_DEBUG_PAD_NAME(pad), GST_DEBUG_PAD_NAME(peerpad), *counter);
+
+  do {
+    gboolean matchtempl;
+
+    matchtempl = gst_caps_check_compatibility (*newcaps, gst_pad_get_padtemplate_caps (GST_PAD (otherpad)));
+
+    GST_DEBUG (GST_CAT_ELEMENT_PADS, "caps compatibility check %d\n", matchtempl);
+
+    if (matchtempl) {
+      if (otherpad->negotiatefunc) {
+        GstRealPad *temp;
+
+        GST_DEBUG (GST_CAT_ELEMENT_PADS, "switching pad for next phase\n");
+
+        temp = currentpad;
+        currentpad = otherpad;
+        otherpad = temp;
+      }
+      else if (gst_caps_check_compatibility (*newcaps, GST_PAD_CAPS (otherpad))) {
+        GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation succeeded\n");
+        return TRUE;
+      }
+      else {
+	*newcaps = GST_PAD_CAPS (otherpad);
+      }
+    }
+    else {
+      *newcaps = GST_PAD_CAPS (otherpad);
+    }
+
+    (*counter)++;
+
+    if (currentpad->negotiatefunc) {
+      GST_DEBUG (GST_CAT_ELEMENT_PADS, "calling negotiate function on pad %s:%s\n",
+		      GST_DEBUG_PAD_NAME (currentpad));
+      result = currentpad->negotiatefunc (GST_PAD (currentpad), newcaps, *counter);
+
+      switch (result) {
+        case GST_PAD_NEGOTIATE_FAIL:
+          GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation failed\n");
+          return FALSE;
+        case GST_PAD_NEGOTIATE_AGREE:
+          GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation succeeded\n");
+          return TRUE;
+        case GST_PAD_NEGOTIATE_TRY:
+          GST_DEBUG (GST_CAT_ELEMENT_PADS, "try another option\n");
+          break;
+      }
+    }
+    else {
+      GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation failed, no more options\n");
+      return FALSE;
+    }
+      
+  } while (*counter < 100);
+
+  GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation failed, too many attempts\n");
+  
+  return FALSE;
+}
+
 /**
  * gst_pad_renegotiate:
  * @pad: the pad to perform the negotiation on
@@ -931,11 +1011,10 @@ cleanup:
 gboolean
 gst_pad_renegotiate (GstPad *pad)
 {
-  gint counter = 0;
   GstCaps *newcaps = NULL;
   GstRealPad *peerpad, *currentpad, *otherpad;
-  GstPadDirection currentdirection;
-  GstPadNegotiateReturn result;
+  gboolean result;
+  gint counter = 0;
   
   g_return_val_if_fail (pad != NULL, FALSE);
 
@@ -957,80 +1036,46 @@ gst_pad_renegotiate (GstPad *pad)
   newcaps = GST_PAD_CAPS (pad);
   g_assert (newcaps != NULL);
 
-  currentdirection = GST_PAD_DIRECTION (currentpad);
+  result = gst_pad_renegotiate_func (pad, GST_PAD (peerpad), &newcaps, &counter);
 
-  do {
-    gboolean matchtempl;
+  if (result) {
+    GST_DEBUG (GST_CAT_ELEMENT_PADS, "pads aggreed on caps :)\n");
 
-    matchtempl = gst_caps_check_compatibility (newcaps, gst_pad_get_padtemplate_caps (GST_PAD (otherpad)));
+    /* here we have some sort of aggreement of the caps */
+    GST_PAD_CAPS (currentpad) = newcaps;
+    GST_PAD_CAPS (otherpad) = newcaps;
+  }
 
-    if (matchtempl) {
-      if (otherpad->negotiatefunc) {
-        GstRealPad *temp;
-
-        temp = currentpad;
-        currentpad = otherpad;
-        otherpad = temp;
-      }
-      else if (gst_caps_check_compatibility (newcaps, GST_PAD_CAPS (otherpad))) {
-        break;
-      }
-      else {
-	newcaps = GST_PAD_CAPS (otherpad);
-      }
-    }
-    else {
-      newcaps = GST_PAD_CAPS (otherpad);
-    }
-
-    counter++;
-
-    if (currentpad->negotiatefunc) {
-      result = currentpad->negotiatefunc (GST_PAD (currentpad), &newcaps, counter);
-
-      switch (result) {
-        case GST_PAD_NEGOTIATE_FAIL:
-          return FALSE;
-        case GST_PAD_NEGOTIATE_AGREE:
-          goto succeed;
-        case GST_PAD_NEGOTIATE_TRY:
-          break;
-      }
-    }
-    else {
-      return FALSE;
-    }
-      
-  } while (counter < 100);
-
-succeed:
-  
-  GST_DEBUG (GST_CAT_ELEMENT_PADS, "pads aggreed on caps :)\n");
-
-  /* here we have some sort of aggreement of the caps */
-  GST_PAD_CAPS (currentpad) = newcaps;
-  GST_PAD_CAPS (otherpad) = newcaps;
-   
-  return TRUE;
+  return result;
 }
 
+   
 GstPadNegotiateReturn
 gst_pad_negotiate_proxy (GstPad *pad, GstCaps **caps, gint counter)
 {
   GstRealPad *peer;
+  gboolean result;
 
   g_return_val_if_fail (pad != NULL, GST_PAD_NEGOTIATE_FAIL);
 
-  GST_DEBUG (GST_CAT_ELEMENT_PADS, "pad (%s:%s) proxied\n", GST_DEBUG_PAD_NAME (pad));
+  GST_DEBUG (GST_CAT_ELEMENT_PADS, "negotiation proxied to pad (%s:%s)\n", GST_DEBUG_PAD_NAME (pad));
 
   peer = GST_RPAD_PEER (pad);
 
   //GST_PAD_CAPS (pad) = caps;
 
   if (peer) {
-    if (peer->negotiatefunc) {
-      GST_DEBUG (GST_CAT_ELEMENT_PADS, "calling negotiate on peer (%s:%s)\n", GST_DEBUG_PAD_NAME (peer));
-      return peer->negotiatefunc (peer, caps, counter);
+    result = gst_pad_renegotiate_func (pad, GST_PAD (peer), caps, &counter);
+
+    if (result) {
+      GST_DEBUG (GST_CAT_ELEMENT_PADS, "pads aggreed on caps :)\n");
+
+      /* here we have some sort of aggreement of the caps */
+      GST_PAD_CAPS (pad) = *caps;
+      GST_PAD_CAPS (peer) = *caps;
+    }
+    else {
+      return GST_PAD_NEGOTIATE_FAIL;
     }
   }
 

gst/gstqueue.c

@@ -153,23 +153,43 @@ gst_queue_init (GstQueue *queue)
 }
 
 static GstPadNegotiateReturn
-gst_queue_handle_negotiate_src (GstPad *pad, GstCaps **caps, gint count)
+gst_queue_handle_negotiate_src (GstPad *pad, GstCaps **caps, gint counter)
 {
   GstQueue *queue;
 
   queue = GST_QUEUE (GST_OBJECT_PARENT (pad));
 
-  return gst_pad_negotiate_proxy (queue->sinkpad, caps, count);
+  if (counter == 0) {
+     *caps = NULL;
+     return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    if (counter == 1) {
+      return gst_pad_negotiate_proxy (queue->sinkpad, caps, counter);
+    }
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
 }
 
 static GstPadNegotiateReturn
-gst_queue_handle_negotiate_sink (GstPad *pad, GstCaps **caps, gint count)
+gst_queue_handle_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
 {
   GstQueue *queue;
 
   queue = GST_QUEUE (GST_OBJECT_PARENT (pad));
 
-  return gst_pad_negotiate_proxy (queue->srcpad, caps, count);
+  if (counter == 0) {
+     *caps = NULL;
+     return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    if (counter == 1) {
+      return gst_pad_negotiate_proxy (queue->srcpad, caps, counter);
+    }
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
 }
 
 static gboolean

plugins/elements/gstqueue.c

@@ -153,23 +153,43 @@ gst_queue_init (GstQueue *queue)
 }
 
 static GstPadNegotiateReturn
-gst_queue_handle_negotiate_src (GstPad *pad, GstCaps **caps, gint count)
+gst_queue_handle_negotiate_src (GstPad *pad, GstCaps **caps, gint counter)
 {
   GstQueue *queue;
 
   queue = GST_QUEUE (GST_OBJECT_PARENT (pad));
 
-  return gst_pad_negotiate_proxy (queue->sinkpad, caps, count);
+  if (counter == 0) {
+     *caps = NULL;
+     return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    if (counter == 1) {
+      return gst_pad_negotiate_proxy (queue->sinkpad, caps, counter);
+    }
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
 }
 
 static GstPadNegotiateReturn
-gst_queue_handle_negotiate_sink (GstPad *pad, GstCaps **caps, gint count)
+gst_queue_handle_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
 {
   GstQueue *queue;
 
   queue = GST_QUEUE (GST_OBJECT_PARENT (pad));
 
-  return gst_pad_negotiate_proxy (queue->srcpad, caps, count);
+  if (counter == 0) {
+     *caps = NULL;
+     return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    if (counter == 1) {
+      return gst_pad_negotiate_proxy (queue->srcpad, caps, counter);
+    }
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
 }
 
 static gboolean

tests/old/testsuite/capsnego/.gitignore

@@ -7,3 +7,4 @@ Makefile.in
 .libs
 capsnego
 converter
+converter2

tests/old/testsuite/capsnego/Makefile.am

@@ -1,6 +1,6 @@
 SUBDIRS =
 
-testprogs = capsnego converter
+testprogs = capsnego converter converter2
 
 TESTS = $(testprogs)
 

tests/old/testsuite/capsnego/converter2.c

@@ -0,0 +1,224 @@
+
+#include <gst/gst.h>
+
+GstPad *srcpad, *sinkpad;
+GstPad *srcconvpad, *sinkconvpad;
+GstPad *srcpadtempl, *sinkpadtempl;
+GstPad *srcconvtempl, *sinkconvtempl;
+
+gint converter_in = -1, converter_out = -1;
+gint target_rate = 2000;
+
+static GstPadFactory src_factory = {
+  "src",
+  GST_PAD_FACTORY_SRC,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory src_conv_factory = {
+  "src",
+  GST_PAD_FACTORY_SRC,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory sink_conv_factory = {
+  "src",
+  GST_PAD_FACTORY_SINK,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory sink_factory = {
+  "sink",
+  GST_PAD_FACTORY_SINK,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_sink",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstCapsFactory sink_caps = {
+  "sink_caps",
+  "audio/raw",
+  "rate",     GST_PROPS_INT (6000),
+  NULL
+};
+
+static GstCapsFactory src_caps = {
+  "src_caps",
+  "audio/raw",
+  "rate",     GST_PROPS_INT (3000),
+  NULL
+};
+
+static GstPadTemplate *srctempl, *sinktempl;
+static GstCaps *srccaps, *sinkcaps;
+
+static GstPadNegotiateReturn
+converter_negotiate_src (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print (">");
+
+  if (counter == 0) {
+    *caps = NULL;
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    converter_out = gst_caps_get_int (*caps, "rate");
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+static GstPadNegotiateReturn
+converter_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print ("<");
+  if (counter == 0) {
+    *caps = GST_PAD_CAPS (srcconvpad);
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    converter_in = gst_caps_get_int (*caps, "rate");
+
+    if (counter == 1) {
+      converter_out = gst_caps_get_int (*caps, "rate");
+      return gst_pad_negotiate_proxy (srcconvpad, caps, counter);
+    }
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+static GstPadNegotiateReturn
+target_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print ("{");
+  if (counter == 0) {
+    *caps = gst_caps_new_with_props (
+		    "target_caps",
+		    "audio/raw",
+		    gst_props_new (
+			    "rate", GST_PROPS_INT (target_rate),
+			    NULL)
+		    );
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    target_rate = gst_caps_get_int (*caps, "rate");
+    g_print ("target set %d\n", target_rate);
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+int 
+main (int argc, char *argv[])
+{
+  gboolean overall = TRUE;
+  gboolean result;
+  
+  gst_init (&argc, &argv);
+
+  srctempl = gst_padtemplate_new (&src_factory);
+  sinktempl = gst_padtemplate_new (&sink_factory);
+  srcpad = gst_pad_new_from_template (srctempl, "src");
+  sinkpad = gst_pad_new_from_template (sinktempl, "sink");
+
+  srcconvtempl = gst_padtemplate_new (&src_conv_factory);
+  sinkconvtempl = gst_padtemplate_new (&sink_conv_factory);
+  srcconvpad = gst_pad_new_from_template (srcconvtempl, "csrc");
+  sinkconvpad = gst_pad_new_from_template (sinkconvtempl, "csink");
+
+  gst_pad_set_negotiate_function (srcconvpad, converter_negotiate_src);
+  gst_pad_set_negotiate_function (sinkconvpad, converter_negotiate_sink);
+  gst_pad_set_negotiate_function (sinkpad, target_negotiate_sink);
+
+  sinkcaps  = gst_caps_register (&sink_caps);
+  srccaps  = gst_caps_register (&src_caps);
+
+  g_print ("-------)      (-----------)       (-----   \n");
+  g_print ("       !      ! converter !       !        \n");
+  g_print ("      src -- csink       csrc -- sink      \n");
+  g_print ("-------)      (-----------)       (-----   \n\n");
+  g_print ("The convertor first tries to proxy the caps received\n");
+  g_print ("on its csink pad to its csrc pad, when that fails, it\n");
+  g_print ("sets up the conversion.\n\n");
+  
+
+  g_print ("sink pad set caps (rate=%d), converter status: %d %d\n", target_rate, 
+		  converter_in, converter_out);
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("result: %d, converter status: %d %d, target: %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  result = gst_pad_connect (srcpad, sinkconvpad);
+  g_print ("pad connect 1: %d\n", result);
+  overall &= (result == TRUE);
+  result = gst_pad_connect (srcconvpad, sinkpad);
+  g_print ("pad connect 2: %d\n", result);
+  overall &= (result == TRUE);
+
+  g_print ("after connect, converter status: %d %d, target %d\n\n", converter_in, converter_out, target_rate);
+
+  g_print ("src pad set caps (rate=%d), converter status: %d %d, target %d \n", gst_caps_get_int (srccaps, "rate"),
+		  converter_in, converter_out, target_rate);
+  result = gst_pad_set_caps (srcpad, srccaps);
+  g_print ("result %d, converter status: %d %d, target %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  g_print ("sink pad set caps (rate=2000), converter status: %d %d, target %d \n",
+		  converter_in, converter_out, target_rate);
+  target_rate = 2000;
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("result %d, converter status: %d %d, target: %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (srccaps, "rate", GST_PROPS_INT (4000));
+  result = gst_pad_renegotiate (srcpad);
+  g_print ("sink pad renegotiate caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (srccaps, "rate", GST_PROPS_INT (40000));
+  result = gst_pad_set_caps (srcpad, srccaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (40000));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  target_rate = 9000;
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  exit (!overall);
+}

testsuite/capsnego/.gitignore

@@ -7,3 +7,4 @@ Makefile.in
 .libs
 capsnego
 converter
+converter2

testsuite/capsnego/Makefile.am

@@ -1,6 +1,6 @@
 SUBDIRS =
 
-testprogs = capsnego converter
+testprogs = capsnego converter converter2
 
 TESTS = $(testprogs)
 

testsuite/capsnego/converter2.c

@@ -0,0 +1,224 @@
+
+#include <gst/gst.h>
+
+GstPad *srcpad, *sinkpad;
+GstPad *srcconvpad, *sinkconvpad;
+GstPad *srcpadtempl, *sinkpadtempl;
+GstPad *srcconvtempl, *sinkconvtempl;
+
+gint converter_in = -1, converter_out = -1;
+gint target_rate = 2000;
+
+static GstPadFactory src_factory = {
+  "src",
+  GST_PAD_FACTORY_SRC,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory src_conv_factory = {
+  "src",
+  GST_PAD_FACTORY_SRC,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory sink_conv_factory = {
+  "src",
+  GST_PAD_FACTORY_SINK,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_src",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstPadFactory sink_factory = {
+  "sink",
+  GST_PAD_FACTORY_SINK,
+  GST_PAD_FACTORY_ALWAYS,
+  GST_PAD_FACTORY_CAPS(
+  "test_sink",
+    "audio/raw",
+    "rate",    GST_PROPS_INT_RANGE (16, 20000)
+  ),
+  NULL,
+};
+
+static GstCapsFactory sink_caps = {
+  "sink_caps",
+  "audio/raw",
+  "rate",     GST_PROPS_INT (6000),
+  NULL
+};
+
+static GstCapsFactory src_caps = {
+  "src_caps",
+  "audio/raw",
+  "rate",     GST_PROPS_INT (3000),
+  NULL
+};
+
+static GstPadTemplate *srctempl, *sinktempl;
+static GstCaps *srccaps, *sinkcaps;
+
+static GstPadNegotiateReturn
+converter_negotiate_src (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print (">");
+
+  if (counter == 0) {
+    *caps = NULL;
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    converter_out = gst_caps_get_int (*caps, "rate");
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+static GstPadNegotiateReturn
+converter_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print ("<");
+  if (counter == 0) {
+    *caps = GST_PAD_CAPS (srcconvpad);
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    converter_in = gst_caps_get_int (*caps, "rate");
+
+    if (counter == 1) {
+      converter_out = gst_caps_get_int (*caps, "rate");
+      return gst_pad_negotiate_proxy (srcconvpad, caps, counter);
+    }
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+static GstPadNegotiateReturn
+target_negotiate_sink (GstPad *pad, GstCaps **caps, gint counter)
+{
+  g_print ("{");
+  if (counter == 0) {
+    *caps = gst_caps_new_with_props (
+		    "target_caps",
+		    "audio/raw",
+		    gst_props_new (
+			    "rate", GST_PROPS_INT (target_rate),
+			    NULL)
+		    );
+    return GST_PAD_NEGOTIATE_TRY;
+  }
+  if (*caps) {
+    target_rate = gst_caps_get_int (*caps, "rate");
+    g_print ("target set %d\n", target_rate);
+    return GST_PAD_NEGOTIATE_AGREE;
+  }
+
+  return GST_PAD_NEGOTIATE_FAIL;
+}
+
+int 
+main (int argc, char *argv[])
+{
+  gboolean overall = TRUE;
+  gboolean result;
+  
+  gst_init (&argc, &argv);
+
+  srctempl = gst_padtemplate_new (&src_factory);
+  sinktempl = gst_padtemplate_new (&sink_factory);
+  srcpad = gst_pad_new_from_template (srctempl, "src");
+  sinkpad = gst_pad_new_from_template (sinktempl, "sink");
+
+  srcconvtempl = gst_padtemplate_new (&src_conv_factory);
+  sinkconvtempl = gst_padtemplate_new (&sink_conv_factory);
+  srcconvpad = gst_pad_new_from_template (srcconvtempl, "csrc");
+  sinkconvpad = gst_pad_new_from_template (sinkconvtempl, "csink");
+
+  gst_pad_set_negotiate_function (srcconvpad, converter_negotiate_src);
+  gst_pad_set_negotiate_function (sinkconvpad, converter_negotiate_sink);
+  gst_pad_set_negotiate_function (sinkpad, target_negotiate_sink);
+
+  sinkcaps  = gst_caps_register (&sink_caps);
+  srccaps  = gst_caps_register (&src_caps);
+
+  g_print ("-------)      (-----------)       (-----   \n");
+  g_print ("       !      ! converter !       !        \n");
+  g_print ("      src -- csink       csrc -- sink      \n");
+  g_print ("-------)      (-----------)       (-----   \n\n");
+  g_print ("The convertor first tries to proxy the caps received\n");
+  g_print ("on its csink pad to its csrc pad, when that fails, it\n");
+  g_print ("sets up the conversion.\n\n");
+  
+
+  g_print ("sink pad set caps (rate=%d), converter status: %d %d\n", target_rate, 
+		  converter_in, converter_out);
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("result: %d, converter status: %d %d, target: %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  result = gst_pad_connect (srcpad, sinkconvpad);
+  g_print ("pad connect 1: %d\n", result);
+  overall &= (result == TRUE);
+  result = gst_pad_connect (srcconvpad, sinkpad);
+  g_print ("pad connect 2: %d\n", result);
+  overall &= (result == TRUE);
+
+  g_print ("after connect, converter status: %d %d, target %d\n\n", converter_in, converter_out, target_rate);
+
+  g_print ("src pad set caps (rate=%d), converter status: %d %d, target %d \n", gst_caps_get_int (srccaps, "rate"),
+		  converter_in, converter_out, target_rate);
+  result = gst_pad_set_caps (srcpad, srccaps);
+  g_print ("result %d, converter status: %d %d, target %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  g_print ("sink pad set caps (rate=2000), converter status: %d %d, target %d \n",
+		  converter_in, converter_out, target_rate);
+  target_rate = 2000;
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("result %d, converter status: %d %d, target: %d\n\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (srccaps, "rate", GST_PROPS_INT (4000));
+  result = gst_pad_renegotiate (srcpad);
+  g_print ("sink pad renegotiate caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (srccaps, "rate", GST_PROPS_INT (40000));
+  result = gst_pad_set_caps (srcpad, srccaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (40000));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  target_rate = 9000;
+  gst_caps_set (sinkcaps, "rate", GST_PROPS_INT (target_rate));
+  result = gst_pad_set_caps (sinkpad, sinkcaps);
+  g_print ("sink pad set caps %d, converter status: %d %d, target: %d\n", result, 
+		  converter_in, converter_out, target_rate);
+
+  exit (!overall);
+}