basertppayload: Make perfect timestamps reproducible across element restart

Without the perfect timestamp machinery, the RTP timestamp can be
computed directly from the running time of a buffer, but the perfect
timestamp patch broke that assumption. This patch restores it by
having the first perfect timestamp be the running time of that buffer
and counting from there.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=654434

diff --git a/gst-libs/gst/rtp/gstbasertppayload.c b/gst-libs/gst/rtp/gstbasertppayload.c
index e27d97a..d7f1aa3 100644 (file)
--- a/gst-libs/gst/rtp/gstbasertppayload.c
+++ b/gst-libs/gst/rtp/gstbasertppayload.c
@@ -20,7 +20,7 @@
  */
 
 #ifdef HAVE_CONFIG_H
-#  include "config.h"
+#include "config.h"
 #endif
 
 #include <string.h>
@@ -44,6 +44,9 @@ struct _GstBaseRTPPayloadPrivate
   gboolean perfect_rtptime;
   gint notified_first_timestamp;
 
+  guint64 base_offset;
+  gint64 base_rtime;
+
   gint64 prop_max_ptime;
   gint64 caps_max_ptime;
 };
@@ -291,6 +294,8 @@ gst_basertppayload_init (GstBaseRTPPayload * basertppayload, gpointer g_class)
   basertppayload->min_ptime = DEFAULT_MIN_PTIME;
   basertppayload->priv->perfect_rtptime = DEFAULT_PERFECT_RTPTIME;
   basertppayload->abidata.ABI.ptime_multiple = DEFAULT_PTIME_MULTIPLE;
+  basertppayload->priv->base_offset = GST_BUFFER_OFFSET_NONE;
+  basertppayload->priv->base_rtime = GST_BUFFER_OFFSET_NONE;
 
   basertppayload->media = NULL;
   basertppayload->encoding_name = NULL;
@@ -414,6 +419,8 @@ gst_basertppayload_event (GstPad * pad, GstEvent * event)
       gst_segment_set_newsegment_full (segment, update, rate, arate, fmt, start,
           stop, position);
 
+      basertppayload->priv->base_offset = GST_BUFFER_OFFSET_NONE;
+
       GST_DEBUG_OBJECT (basertppayload,
           "configured NEWSEGMENT update %d, rate %lf, applied rate %lf, "
           "format %d, "
@@ -775,9 +782,11 @@ gst_basertppayload_prepare_push (GstBaseRTPPayload * payload,
   }
 
   /* convert to RTP time */
-  if (priv->perfect_rtptime && data.offset != GST_BUFFER_OFFSET_NONE) {
+  if (priv->perfect_rtptime && data.offset != GST_BUFFER_OFFSET_NONE &&
+      priv->base_offset != GST_BUFFER_OFFSET_NONE) {
     /* if we have an offset, use that for making an RTP timestamp */
-    data.rtptime = payload->ts_base + data.offset;
+    data.rtptime = payload->ts_base + priv->base_rtime +
+        data.offset - priv->base_offset;
     GST_LOG_OBJECT (payload,
         "Using offset %" G_GUINT64_FORMAT " for RTP timestamp", data.offset);
   } else if (GST_CLOCK_TIME_IS_VALID (data.timestamp)) {
@@ -796,6 +805,8 @@ gst_basertppayload_prepare_push (GstBaseRTPPayload * payload,
           GST_TIME_ARGS (rtime));
       rtime =
           gst_util_uint64_scale_int (rtime, payload->clock_rate, GST_SECOND);
+      priv->base_offset = data.offset;
+      priv->base_rtime = rtime;
     }
     /* add running_time in clock-rate units to the base timestamp */
     data.rtptime = payload->ts_base + rtime;
@@ -1045,6 +1056,7 @@ gst_basertppayload_change_state (GstElement * element,
         basertppayload->ts_base = basertppayload->ts_offset;
       basertppayload->timestamp = basertppayload->ts_base;
       g_atomic_int_set (&basertppayload->priv->notified_first_timestamp, 1);
+      priv->base_offset = GST_BUFFER_OFFSET_NONE;
       break;
     default:
       break;