add arch

@@ -72,6 +72,36 @@ rtmp url: rtmp://demo:19350/live/livestream_sd
 m3u8 url: http://demo:80/forward/live/livestream_sd.m3u8
 </pre>
 
+### Architecture
+System Architecture:
+<pre>
++------------------------------------------------------+
+|        Srs(Simple Rtmp Server)                       |
++---------------+---------------+-----------+----------+
+|   API/hook    |   Transcoder  |    HLS    |   RTMP   |
+|  http-parser  |  FFMPEG/x264  |  NGINX/ts | protocol |
++---------------+---------------+-----------+----------+
+|        Network(state-threads)                        |
++------------------------------------------------------+
+|  All Linux(RHEL,Centos,Ubuntu,Fedora...)             |
++------------------------------------------------------+
+</pre>
+Stream Architecture:
+<pre>
+        +---------+             +----------+  
+        + Publish +             +  Deliver |  
+        +---|-----+             +----|-----+  
++-----------+------------------------+-----------------+
+| Encoder   |       SRS              |     Client      |
++-----------+------------------------+-----------------+
+| (FMLE,    |   +-> RTMP protocol ---+-> Flash Player  |
+| FFMPEG, --+-> +-> HLS/NGINX -------+-> m3u8 player   |
+| Flash,    |   +-> Fowarder --------+-> RTMP Server   |
+| XSPLIT,   |   +-> Transcoder ------+-> RTMP Server   |
+|  ...)     |   +-> DVR -------------+-> FILE          |
++-----------+------------------------+-----------------+
+</pre>
+
 ### System Requirements
 Supported operating systems and hardware:
 * All Linux , both 32 and 64 bits