ffmpegenc: Use dash instead of underscore in property names

GLib internally converts them to dashs anyway.

ext/ffmpeg/gstffmpegenc.c

@@ -181,17 +181,17 @@ gst_ffmpegenc_class_init (GstFFMpegEncClass * klass)
             "Target Video Bitrate", 0, G_MAXULONG, DEFAULT_VIDEO_BITRATE,
             G_PARAM_READWRITE));
     g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_GOP_SIZE,
-        g_param_spec_int ("gop_size", "GOP Size",
+        g_param_spec_int ("gop-size", "GOP Size",
             "Number of frames within one GOP", 0, G_MAXINT,
             DEFAULT_VIDEO_GOP_SIZE, G_PARAM_READWRITE));
     g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_ME_METHOD,
-        g_param_spec_enum ("me_method", "ME Method", "Motion Estimation Method",
+        g_param_spec_enum ("me-method", "ME Method", "Motion Estimation Method",
             GST_TYPE_ME_METHOD, ME_EPZS, G_PARAM_READWRITE));
     g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_BUFSIZE,
-        g_param_spec_ulong ("buffer_size", "Buffer Size",
+        g_param_spec_ulong ("buffer-size", "Buffer Size",
             "Size of the video buffers", 0, G_MAXULONG, 0, G_PARAM_READWRITE));
     g_object_class_install_property (G_OBJECT_CLASS (klass),
-        ARG_RTP_PAYLOAD_SIZE, g_param_spec_ulong ("rtp_payload_size",
+        ARG_RTP_PAYLOAD_SIZE, g_param_spec_ulong ("rtp-payload-size",
             "RTP Payload Size", "Target GOB length", 0, G_MAXULONG, 0,
             G_PARAM_READWRITE));