rtponviftimestamp: add opt-out "drop-out-of-segment" property

The default behaviour of rtponviftimestamp is to drop buffers
outside the segment. This creates obvious problems for reverse
playback.

The ONVIF specification unfortunately doesn't describe how to handle
that specific use case, but we can expose a property to let the
user disable the dropping behaviour, and forward these buffers with
a G_MAXUINT64 ONVIF timestamp.

Also modify rtponvifparse to handle such timestamps appropriately.

gst/onvif/gstrtponvifparse.c

@@ -118,8 +118,13 @@ handle_buffer (GstRtpOnvifParse * self, GstBuffer * buf, gboolean * send_eos)
   timestamp_fraction = GST_READ_UINT32_BE (data + 4);
   timestamp_nseconds =
       (timestamp_fraction * G_GINT64_CONSTANT (1000000000)) >> 32;
-  GST_BUFFER_PTS (buf) =
-      timestamp_seconds * GST_SECOND + timestamp_nseconds * GST_NSECOND;
+
+  if (timestamp_seconds == G_MAXUINT32 && timestamp_fraction == G_MAXUINT32) {
+    GST_BUFFER_PTS (buf) = GST_CLOCK_TIME_NONE;
+  } else {
+    GST_BUFFER_PTS (buf) =
+        timestamp_seconds * GST_SECOND + timestamp_nseconds * GST_NSECOND;
+  }
 
   flags = GST_READ_UINT8 (data + 8);
   /* cseq = GST_READ_UINT8 (data + 9);  TODO */

gst/onvif/gstrtponviftimestamp.c

@@ -36,6 +36,7 @@
 #define DEFAULT_CSEQ 0
 #define DEFAULT_SET_E_BIT FALSE
 #define DEFAULT_SET_T_BIT FALSE
+#define DEFAULT_DROP_OUT_OF_SEGMENT TRUE
 
 GST_DEBUG_CATEGORY_STATIC (rtponviftimestamp_debug);
 #define GST_CAT_DEFAULT (rtponviftimestamp_debug)
@@ -71,6 +72,7 @@ enum
   PROP_CSEQ,
   PROP_SET_E_BIT,
   PROP_SET_T_BIT,
+  PROP_DROP_OUT_OF_SEGMENT
 };
 
 /*static guint gst_rtp_onvif_timestamp_signals[LAST_SIGNAL] = { 0 }; */
@@ -96,6 +98,8 @@ gst_rtp_onvif_timestamp_get_property (GObject * object,
     case PROP_SET_T_BIT:
       g_value_set_boolean (value, self->prop_set_t_bit);
       break;
+    case PROP_DROP_OUT_OF_SEGMENT:
+      g_value_set_boolean (value, self->prop_drop_out_of_segment);
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -121,6 +125,9 @@ gst_rtp_onvif_timestamp_set_property (GObject * object,
     case PROP_SET_T_BIT:
       self->prop_set_t_bit = g_value_get_boolean (value);
       break;
+    case PROP_DROP_OUT_OF_SEGMENT:
+      self->prop_drop_out_of_segment = g_value_get_boolean (value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -271,6 +278,13 @@ gst_rtp_onvif_timestamp_class_init (GstRtpOnvifTimestampClass * klass)
           "extension. This increases latency by one packet",
           DEFAULT_SET_T_BIT, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
+  g_object_class_install_property (gobject_class, PROP_DROP_OUT_OF_SEGMENT,
+      g_param_spec_boolean ("drop-out-of-segment", "Drop out of segment",
+          "Whether the element should drop buffers that fall outside the segment, "
+          "not part of the specification but allows full reverse playback.",
+          DEFAULT_DROP_OUT_OF_SEGMENT,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   /* register pads */
   gst_element_class_add_static_pad_template (gstelement_class,
       &sink_template_factory);
@@ -438,6 +452,7 @@ gst_rtp_onvif_timestamp_init (GstRtpOnvifTimestamp * self)
   self->prop_ntp_offset = DEFAULT_NTP_OFFSET;
   self->prop_set_e_bit = DEFAULT_SET_E_BIT;
   self->prop_set_t_bit = DEFAULT_SET_T_BIT;
+  self->prop_drop_out_of_segment = DEFAULT_DROP_OUT_OF_SEGMENT;
 
   gst_segment_init (&self->segment, GST_FORMAT_UNDEFINED);
 
@@ -530,18 +545,20 @@ handle_buffer (GstRtpOnvifTimestamp * self, GstBuffer * buf)
     goto done;
   }
 
-  if (time == GST_CLOCK_TIME_NONE) {
+  if (self->prop_drop_out_of_segment && time == GST_CLOCK_TIME_NONE) {
     GST_ERROR_OBJECT (self, "Failed to get stream time");
-    goto done;
+    gst_rtp_buffer_unmap (&rtp);
+    return FALSE;
   }
 
   /* add the offset (in seconds) */
-  time += self->ntp_offset;
-
-  /* convert to NTP time. upper 32 bits should contain the seconds
-   * and the lower 32 bits, the fractions of a second. */
-  time = gst_util_uint64_scale (time, (G_GINT64_CONSTANT (1) << 32),
-      GST_SECOND);
+  if (time != GST_CLOCK_TIME_NONE) {
+    time += self->ntp_offset;
+    /* convert to NTP time. upper 32 bits should contain the seconds
+     * and the lower 32 bits, the fractions of a second. */
+    time = gst_util_uint64_scale (time, (G_GINT64_CONSTANT (1) << 32),
+        GST_SECOND);
+  }
 
   GST_DEBUG_OBJECT (self, "timestamp: %" G_GUINT64_FORMAT, time);
 

gst/onvif/gstrtponviftimestamp.h

@@ -52,6 +52,7 @@ struct _GstRtpOnvifTimestamp {
   guint prop_cseq;
   gboolean prop_set_e_bit;
   gboolean prop_set_t_bit;
+  gboolean prop_drop_out_of_segment;
 
   /* currently used ntp-offset
    *(can be changed runtime with a GstNtpOffset event)