From 08ac05a06c30cc8a5608d85130209db5c731d3eb Mon Sep 17 00:00:00 2001
From: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Date: Thu, 25 Aug 2011 15:14:58 +0100
Subject: [PATCH] videorate: fix dynamically changing average period

The average_period_set variable can be accessed in different threads, so
always lock it when reading. Furthermore when switching to averaging
mode we should make sure we don't have cached buffers that aren't used
in that mode. And any modeswitch will cause the latency to change, so we
should post a NewLatency message
---
 gst/videorate/gstvideorate.c | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/gst/videorate/gstvideorate.c b/gst/videorate/gstvideorate.c
index 9af4f8d..32f15fe 100644
--- a/gst/videorate/gstvideorate.c
+++ b/gst/videorate/gstvideorate.c
@@ -645,10 +645,14 @@ gst_video_rate_query (GstBaseTransform * trans, GstPadDirection direction,
       GstClockTime min, max;
       gboolean live;
       guint64 latency;
+      guint64 avg_period;
       GstPad *peer;
 
-      if (videorate->average_period == 0
-          && (peer = gst_pad_get_peer (otherpad))) {
+      GST_OBJECT_LOCK (videorate);
+      avg_period = videorate->average_period_set;
+      GST_OBJECT_UNLOCK (videorate);
+
+      if (avg_period == 0 && (peer = gst_pad_get_peer (otherpad))) {
         if ((res = gst_pad_query (peer, query))) {
           gst_query_parse_latency (query, &live, &min, &max);
 
@@ -682,8 +686,10 @@ gst_video_rate_query (GstBaseTransform * trans, GstPadDirection direction,
           gst_query_set_latency (query, live, min, max);
         }
         gst_object_unref (peer);
+        break;
       }
-      break;
+      /* Simple fallthrough if we don't have a latency or not a peer that we
+       * can't ask about its latency yet.. */
     }
     default:
       res = parent_class->query (trans, direction, query);
@@ -783,17 +789,25 @@ gst_video_rate_transform_ip (GstBaseTransform * trans, GstBuffer * buffer)
 
   /* MT-safe switching between modes */
   if (G_UNLIKELY (avg_period != videorate->average_period)) {
+    gboolean switch_mode = (avg_period == 0 || videorate->average_period == 0);
     videorate->average_period = avg_period;
     videorate->last_ts = GST_CLOCK_TIME_NONE;
-    if (avg_period && !videorate->average) {
-      /* enabling average mode */
-      videorate->average = 0;
-    } else {
-      /* enable regular mode */
-      gst_video_rate_swap_prev (videorate, NULL, 0);
-      /* arrange for skip-to-first behaviour */
-      videorate->next_ts = GST_CLOCK_TIME_NONE;
-      skip = TRUE;
+
+    if (switch_mode) {
+      if (avg_period) {
+        /* enabling average mode */
+        videorate->average = 0;
+        /* make sure no cached buffers from regular mode are left */
+        gst_video_rate_swap_prev (videorate, NULL, 0);
+      } else {
+        /* enable regular mode */
+        videorate->next_ts = GST_CLOCK_TIME_NONE;
+        skip = TRUE;
+      }
+
+      /* max averaging mode has a no latency, normal mode does */
+      gst_element_post_message (GST_ELEMENT (videorate),
+          gst_message_new_latency (GST_OBJECT (videorate)));
     }
   }
 
@@ -980,7 +994,9 @@ gst_video_rate_set_property (GObject * object,
       videorate->drop_only = g_value_get_boolean (value);
       break;
     case ARG_AVERAGE_PERIOD:
+      GST_OBJECT_LOCK (videorate);
       videorate->average_period_set = g_value_get_uint64 (value);
+      GST_OBJECT_UNLOCK (videorate);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -1022,7 +1038,9 @@ gst_video_rate_get_property (GObject * object,
       g_value_set_boolean (value, videorate->drop_only);
       break;
     case ARG_AVERAGE_PERIOD:
+      GST_OBJECT_LOCK (videorate);
       g_value_set_uint64 (value, videorate->average_period_set);
+      GST_OBJECT_UNLOCK (videorate);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-- 
2.7.4