From 00056965e88a91492bd156d21dae390e4e9f97fd Mon Sep 17 00:00:00 2001
From: Wim Taymans <wim.taymans@collabora.co.uk>
Date: Mon, 30 Sep 2013 12:31:00 +0200
Subject: [PATCH] rtpjitterbuffer: fix race when updating the next_seqnum

If we were not waiting for the missing seqnum when we insert the lost packet
event in the jitterbuffer, we end up not updating the next_seqnum and wait
forever for the lost packets to arrive. Instead, keep track of the amount of
packets contained by the jitterbuffer item and update the next expected
seqnum only after pushing the buffer/event. This makes sure we correctly handle
GAPS in the sequence numbers.
---
 gst/rtpmanager/gstrtpjitterbuffer.c | 21 ++++++---------------
 gst/rtpmanager/rtpjitterbuffer.h    |  2 ++
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/gst/rtpmanager/gstrtpjitterbuffer.c b/gst/rtpmanager/gstrtpjitterbuffer.c
index b0ca564..60d384d 100644
--- a/gst/rtpmanager/gstrtpjitterbuffer.c
+++ b/gst/rtpmanager/gstrtpjitterbuffer.c
@@ -716,7 +716,7 @@ gst_rtp_jitter_buffer_init (GstRtpJitterBuffer * jitterbuffer)
 
 static RTPJitterBufferItem *
 alloc_item (gpointer data, guint type, GstClockTime dts, GstClockTime pts,
-    guint seqnum, guint rtptime)
+    guint seqnum, guint count, guint rtptime)
 {
   RTPJitterBufferItem *item;
 
@@ -728,6 +728,7 @@ alloc_item (gpointer data, guint type, GstClockTime dts, GstClockTime pts,
   item->dts = dts;
   item->pts = pts;
   item->seqnum = seqnum;
+  item->count = count;
   item->rtptime = rtptime;
 
   return item;
@@ -2085,7 +2086,7 @@ gst_rtp_jitter_buffer_chain (GstPad * pad, GstObject * parent,
     }
   }
 
-  item = alloc_item (buffer, ITEM_TYPE_BUFFER, dts, pts, seqnum, rtptime);
+  item = alloc_item (buffer, ITEM_TYPE_BUFFER, dts, pts, seqnum, 1, rtptime);
 
   /* now insert the packet into the queue in sorted order. This function returns
    * FALSE if a packet with the same seqnum was already in the queue, meaning we
@@ -2306,7 +2307,7 @@ pop_and_push_next (GstRtpJitterBuffer * jitterbuffer, guint16 seqnum)
   /* now we are ready to push the buffer. Save the seqnum and release the lock
    * so the other end can push stuff in the queue again. */
   priv->last_popped_seqnum = seqnum;
-  priv->next_seqnum = (seqnum + 1) & 0xffff;
+  priv->next_seqnum = (seqnum + item->count) & 0xffff;
   JBUF_UNLOCK (priv);
 
   item->data = NULL;
@@ -2483,7 +2484,7 @@ do_lost_timeout (GstRtpJitterBuffer * jitterbuffer, TimerData * timer,
 {
   GstRtpJitterBufferPrivate *priv = jitterbuffer->priv;
   GstClockTime duration, timestamp;
-  guint seqnum, next_seqnum, lost_packets, num_rtx_retry;
+  guint seqnum, lost_packets, num_rtx_retry;
   gboolean late;
   GstEvent *event;
   RTPJitterBufferItem *item;
@@ -2507,8 +2508,6 @@ do_lost_timeout (GstRtpJitterBuffer * jitterbuffer, TimerData * timer,
   priv->num_late += lost_packets;
   priv->num_rtx_failed += num_rtx_retry;
 
-  next_seqnum = seqnum + lost_packets - 1;
-
   /* create paket lost event */
   event = gst_event_new_custom (GST_EVENT_CUSTOM_DOWNSTREAM,
       gst_structure_new ("GstRTPPacketLost",
@@ -2518,17 +2517,9 @@ do_lost_timeout (GstRtpJitterBuffer * jitterbuffer, TimerData * timer,
           "late", G_TYPE_BOOLEAN, late,
           "retry", G_TYPE_UINT, num_rtx_retry, NULL));
 
-  item = alloc_item (event, ITEM_TYPE_LOST, -1, -1, next_seqnum, -1);
+  item = alloc_item (event, ITEM_TYPE_LOST, -1, -1, seqnum, lost_packets, -1);
   rtp_jitter_buffer_insert (priv->jbuf, item, NULL, NULL);
 
-  if (seqnum == priv->next_seqnum) {
-    GST_DEBUG_OBJECT (jitterbuffer, "lost seqnum %d == %d next_seqnum -> %d",
-        seqnum, priv->next_seqnum, next_seqnum);
-    priv->next_seqnum = next_seqnum & 0xffff;
-    priv->last_popped_seqnum = next_seqnum;
-    priv->last_out_time = timestamp;
-  }
-
   /* remove timer now */
   remove_timer (jitterbuffer, timer);
   JBUF_SIGNAL_EVENT (priv);
diff --git a/gst/rtpmanager/rtpjitterbuffer.h b/gst/rtpmanager/rtpjitterbuffer.h
index 49817bf..1389f26 100644
--- a/gst/rtpmanager/rtpjitterbuffer.h
+++ b/gst/rtpmanager/rtpjitterbuffer.h
@@ -109,6 +109,7 @@ struct _RTPJitterBufferClass {
  * @dts: input DTS
  * @pts: output PTS
  * @seqnum: seqnum
+ * @count: amount of seqnum in this item
  * @rtptime: rtp timestamp
  *
  * An object containing an RTP packet or event.
@@ -121,6 +122,7 @@ struct _RTPJitterBufferItem {
   GstClockTime dts;
   GstClockTime pts;
   guint seqnum;
+  guint count;
   guint rtptime;
 };
 
-- 
2.7.4