diff --git a/ChangeLog b/ChangeLog
index 984f9cd319..448dc191ec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2008-08-25  Wim Taymans  <wim.taymans@collabora.co.uk>
+
+	* gst/law/alaw-encode.c: (gst_alaw_enc_init), (gst_alaw_enc_chain):
+	* gst/law/mulaw-conversion.c:
+	* gst/law/mulaw-encode.c: (gst_mulawenc_init),
+	(gst_mulawenc_chain):
+	The encoder can't really renegotiate at the time they perform a
+	pad-alloc so make the srcpads use fixed caps.
+	Check the buffer size after a pad-alloc because the returned size might
+	not be right when the downstream element does not know the size of the
+	new buffer (capsfilter). Fixes #549073.
+
 2008-08-23  Sebastian Dröge  <sebastian.droege@collabora.co.uk>
 
         Patch by: Filippo Argiolas <filippo dot argiolas at gmail dot com>
diff --git a/gst/law/alaw-encode.c b/gst/law/alaw-encode.c
index 215b6691f3..2585eb64f5 100644
--- a/gst/law/alaw-encode.c
+++ b/gst/law/alaw-encode.c
@@ -421,6 +421,7 @@ gst_alaw_enc_init (GstALawEnc * alawenc, GstALawEncClass * klass)
       GST_DEBUG_FUNCPTR (gst_alaw_enc_setcaps));
   gst_pad_set_getcaps_function (alawenc->srcpad,
       GST_DEBUG_FUNCPTR (gst_alaw_enc_getcaps));
+  gst_pad_use_fixed_caps (alawenc->srcpad);
   gst_element_add_pad (GST_ELEMENT (alawenc), alawenc->srcpad);
 
   /* init rest */
@@ -457,11 +458,6 @@ gst_alaw_enc_chain (GstPad * pad, GstBuffer * buffer)
   GST_LOG_OBJECT (alawenc, "buffer with ts=%" GST_TIME_FORMAT,
       GST_TIME_ARGS (timestamp));
 
-  if (duration == GST_CLOCK_TIME_NONE) {
-    duration = gst_util_uint64_scale_int (alaw_size,
-        GST_SECOND, alawenc->rate * alawenc->channels);
-  }
-
   ret =
       gst_pad_alloc_buffer_and_set_caps (alawenc->srcpad,
       GST_BUFFER_OFFSET_NONE, alaw_size, GST_PAD_CAPS (alawenc->srcpad),
@@ -469,6 +465,17 @@ gst_alaw_enc_chain (GstPad * pad, GstBuffer * buffer)
   if (ret != GST_FLOW_OK)
     goto done;
 
+  if (duration == GST_CLOCK_TIME_NONE) {
+    duration = gst_util_uint64_scale_int (alaw_size,
+        GST_SECOND, alawenc->rate * alawenc->channels);
+  }
+
+  if (GST_BUFFER_SIZE (outbuf) < alaw_size) {
+    /* pad-alloc can return a smaller buffer */
+    gst_buffer_unref (outbuf);
+    outbuf = gst_buffer_new_and_alloc (alaw_size);
+  }
+
   alaw_data = (guint8 *) GST_BUFFER_DATA (outbuf);
 
   /* copy discont flag */
diff --git a/gst/law/mulaw-conversion.c b/gst/law/mulaw-conversion.c
index 5cee843640..23e53a1d41 100644
--- a/gst/law/mulaw-conversion.c
+++ b/gst/law/mulaw-conversion.c
@@ -25,7 +25,7 @@
 
 #include <glib.h>
 
-/* #define ZEROTRAP *//* turn on the trap as per the MIL-STD */
+#undef ZEROTRAP                 /* turn on the trap as per the MIL-STD */
 #define BIAS 0x84               /* define the add-in bias for 16 bit samples */
 #define CLIP 32635
 
diff --git a/gst/law/mulaw-encode.c b/gst/law/mulaw-encode.c
index e926b9925b..033665e4df 100644
--- a/gst/law/mulaw-encode.c
+++ b/gst/law/mulaw-encode.c
@@ -194,6 +194,7 @@ gst_mulawenc_init (GstMuLawEnc * mulawenc)
   mulawenc->srcpad = gst_pad_new_from_template (mulawenc_src_template, "src");
   gst_pad_set_setcaps_function (mulawenc->srcpad, mulawenc_setcaps);
   gst_pad_set_getcaps_function (mulawenc->srcpad, mulawenc_getcaps);
+  gst_pad_use_fixed_caps (mulawenc->srcpad);
   gst_element_add_pad (GST_ELEMENT (mulawenc), mulawenc->srcpad);
 
   /* init rest */
@@ -225,17 +226,23 @@ gst_mulawenc_chain (GstPad * pad, GstBuffer * buffer)
 
   timestamp = GST_BUFFER_TIMESTAMP (buffer);
   duration = GST_BUFFER_DURATION (buffer);
+
+  ret = gst_pad_alloc_buffer_and_set_caps (mulawenc->srcpad,
+      GST_BUFFER_OFFSET_NONE, mulaw_size, GST_PAD_CAPS (mulawenc->srcpad),
+      &outbuf);
+  if (ret != GST_FLOW_OK)
+    goto alloc_failed;
+
   if (duration == -1) {
     duration = gst_util_uint64_scale_int (mulaw_size,
         GST_SECOND, mulawenc->rate * mulawenc->channels);
   }
 
-  ret =
-      gst_pad_alloc_buffer_and_set_caps (mulawenc->srcpad,
-      GST_BUFFER_OFFSET_NONE, mulaw_size, GST_PAD_CAPS (mulawenc->srcpad),
-      &outbuf);
-  if (ret != GST_FLOW_OK)
-    goto alloc_failed;
+  if (GST_BUFFER_SIZE (outbuf) < mulaw_size) {
+    /* pad-alloc can suggest a smaller size */
+    gst_buffer_unref (outbuf);
+    outbuf = gst_buffer_new_and_alloc (mulaw_size);
+  }
 
   mulaw_data = (guint8 *) GST_BUFFER_DATA (outbuf);