videoencoder: Add gst_video_encoder_set_min_pts()

For streams with reordered frames this can be used to ensure that there
is enough time to accomodate first DTS, which may be less than first PTS

https://bugzilla.gnome.org/show_bug.cgi?id=740575

gst-libs/gst/video/gstvideoencoder.c

@@ -164,6 +164,11 @@ struct _GstVideoEncoderPrivate
 
   GstTagList *tags;
   gboolean tags_changed;
+
+  GstClockTime min_pts;
+  /* adjustment needed on pts, dts, segment start and stop to accomodate
+   * min_pts */
+  GstClockTime time_adjustment;
 };
 
 typedef struct _ForcedKeyUnitEvent ForcedKeyUnitEvent;
@@ -343,6 +348,8 @@ gst_video_encoder_reset (GstVideoEncoder * encoder, gboolean hard)
   priv->bytes = 0;
   priv->time = 0;
 
+  priv->time_adjustment = GST_CLOCK_TIME_NONE;
+
   if (hard) {
     gst_segment_init (&encoder->input_segment, GST_FORMAT_TIME);
     gst_segment_init (&encoder->output_segment, GST_FORMAT_TIME);
@@ -455,6 +462,8 @@ gst_video_encoder_init (GstVideoEncoder * encoder, GstVideoEncoderClass * klass)
 
   priv->min_latency = 0;
   priv->max_latency = 0;
+  priv->min_pts = GST_CLOCK_TIME_NONE;
+  priv->time_adjustment = GST_CLOCK_TIME_NONE;
 
   gst_video_encoder_reset (encoder, TRUE);
 }
@@ -885,8 +894,19 @@ gst_video_encoder_push_event (GstVideoEncoder * encoder, GstEvent * event)
         break;
       }
 
+      if (encoder->priv->time_adjustment != GST_CLOCK_TIME_NONE) {
+        segment.start += encoder->priv->time_adjustment;
+        if (GST_CLOCK_TIME_IS_VALID (segment.stop)) {
+          segment.stop += encoder->priv->time_adjustment;
+        }
+      }
+
       encoder->output_segment = segment;
       GST_VIDEO_ENCODER_STREAM_UNLOCK (encoder);
+
+      gst_event_unref (event);
+      event = gst_event_new_segment (&encoder->output_segment);
+
       break;
     }
     default:
@@ -1323,6 +1343,17 @@ gst_video_encoder_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
   else
     duration = GST_CLOCK_TIME_NONE;
 
+  if (priv->min_pts != GST_CLOCK_TIME_NONE
+      && priv->time_adjustment == GST_CLOCK_TIME_NONE) {
+    if (cstart < priv->min_pts) {
+      priv->time_adjustment = priv->min_pts - cstart;
+    }
+  }
+
+  if (priv->time_adjustment != GST_CLOCK_TIME_NONE) {
+    cstart += priv->time_adjustment;
+  }
+
   /* incoming DTS is not really relevant and does not make sense anyway,
    * so pass along _NONE and maybe come up with something better later on */
   frame = gst_video_encoder_new_frame (encoder, buf, cstart,
@@ -2297,3 +2328,22 @@ gst_video_encoder_get_allocator (GstVideoEncoder * encoder,
   if (params)
     *params = encoder->priv->params;
 }
+
+/**
+ * Request minimal value for PTS passed to handle_frame.
+ *
+ * For streams with reordered frames this can be used to ensure that there
+ * is enough time to accomodate first DTS, which may be less than first PTS
+ *
+ * @encoder: a #GstVideoEncoder
+ * @min_pts: minimal PTS that will be passed to handle_frame
+ *
+ * Since 1.6
+ */
+void
+gst_video_encoder_set_min_pts (GstVideoEncoder * encoder, GstClockTime min_pts)
+{
+  g_return_if_fail (GST_IS_VIDEO_ENCODER (encoder));
+  encoder->priv->min_pts = min_pts;
+  encoder->priv->time_adjustment = GST_CLOCK_TIME_NONE;
+}

gst-libs/gst/video/gstvideoencoder.h

@@ -333,6 +333,8 @@ void                 gst_video_encoder_get_allocator (GstVideoEncoder *encoder,
                                                       GstAllocator **allocator,
                                                       GstAllocationParams *params);
 
+void                 gst_video_encoder_set_min_pts(GstVideoEncoder *encoder, GstClockTime min_pts);
+
 G_END_DECLS
 
 #endif

win32/common/libgstvideo.def

@@ -148,6 +148,7 @@ EXPORTS
 	gst_video_encoder_proxy_getcaps
 	gst_video_encoder_set_headers
 	gst_video_encoder_set_latency
+	gst_video_encoder_set_min_pts
 	gst_video_encoder_set_output_state
 	gst_video_event_is_force_key_unit
 	gst_video_event_new_downstream_force_key_unit