add transcode for demo meeting hls.

@@ -192,13 +192,13 @@ vhost players_chat {
             vfilter {
             }
             vcodec          libx264;
-            vbitrate        300;
+            vbitrate        150;
             vfps            15;
-            vwidth          768;
-            vheight         320;
+            vwidth          576;
+            vheight         240;
             vthreads        1;
             vprofile        baseline;
-            vpreset         fast;
+            vpreset         ultrafast;
             vparams {
                 g           30;
             }