video{en,de}coder: Call reset() before the start() vfunc

This makes sure that the element is in the same state before start() is called
the very first time and every future call after the element was used already.

Also it ensure that we always have a clean state before start(), cleaned the
same way in every case.

gst-libs/gst/video/gstvideodecoder.c

@@ -2275,12 +2275,13 @@ gst_video_decoder_change_state (GstElement * element, GstStateChange transition)
         goto open_failed;
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
-      /* Initialize device/library if needed */
-      if (decoder_class->start && !decoder_class->start (decoder))
-        goto start_failed;
       GST_VIDEO_DECODER_STREAM_LOCK (decoder);
       gst_video_decoder_reset (decoder, TRUE, TRUE);
       GST_VIDEO_DECODER_STREAM_UNLOCK (decoder);
+
+      /* Initialize device/library if needed */
+      if (decoder_class->start && !decoder_class->start (decoder))
+        goto start_failed;
       break;
     default:
       break;

gst-libs/gst/video/gstvideoencoder.c

@@ -1411,12 +1411,13 @@ gst_video_encoder_change_state (GstElement * element, GstStateChange transition)
         goto open_failed;
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
-      /* Initialize device/library if needed */
-      if (encoder_class->start && !encoder_class->start (encoder))
-        goto start_failed;
       GST_VIDEO_ENCODER_STREAM_LOCK (encoder);
       gst_video_encoder_reset (encoder, TRUE);
       GST_VIDEO_ENCODER_STREAM_UNLOCK (encoder);
+
+      /* Initialize device/library if needed */
+      if (encoder_class->start && !encoder_class->start (encoder))
+        goto start_failed;
       break;
     default:
       break;