diff --git a/linphone/mediastreamer2/src/speexec.c b/linphone/mediastreamer2/src/speexec.c
index 102da1706..c94cdd386 100644
--- a/linphone/mediastreamer2/src/speexec.c
+++ b/linphone/mediastreamer2/src/speexec.c
@@ -104,12 +104,27 @@ static void speex_ec_process(MSFilter *f){
 			int size=msgdsize(m);
     	  	md = copyb(m);
 	      	s->size_delay = s->size_delay + size;
-			ms_queue_put(f->outputs[0],md);
+			ms_bufferizer_put(&s->speak_delay,md);
     	  	ms_bufferizer_put(&s->in[0],m);
 		}
 
-		while((m=ms_queue_get(f->inputs[1]))!=NULL){
-    		ms_queue_put(f->outputs[1],m);
+		/* make sure we always send block with same size */
+		while (ms_bufferizer_get_avail(&s->speak_delay)>=nbytes)
+		{
+			om0=allocb(nbytes,0);
+			ms_bufferizer_read(&s->speak_delay,(uint8_t*)om0->b_wptr,nbytes);
+			om0->b_wptr+=nbytes;
+			ms_queue_put(f->outputs[0],om0);
+		}
+
+		/* make sure we always send block with same size */
+		ms_bufferizer_put_from_queue(&s->in[1],f->inputs[1]);
+		while (ms_bufferizer_get_avail(&s->in[1])>=nbytes)
+		{
+			om0=allocb(nbytes,0);
+			ms_bufferizer_read(&s->in[1],(uint8_t*)om0->b_wptr,nbytes);
+			om0->b_wptr+=nbytes;
+    		ms_queue_put(f->outputs[1],om0);
 		}
 		/* we are now equal and speaker is delayed */
 		return;
@@ -163,7 +178,7 @@ static void speex_ec_process(MSFilter *f){
 			count=0;
 		}		
 #endif
-    freeb(om0);
+		freeb(om0);
 	}
 
 	if (ms_bufferizer_get_avail(&s->speak_delay)> 4*320*(s->samplerate/8000)) /* above 4*20ms -> useless */