add ffmpeg build script

@@ -8,11 +8,13 @@ st-1.9.zip
 	basic framework for srs.
 
 ffmpeg-2.1.1.tar.gz
+yasm-1.2.0.tar.gz
 lame-3.99.5.tar.gz
 libaacplus-2.0.2.tar.gz
-libaacplus-patch-26410-b00.zip
+libaacplus-patch-26410-800.zip (26410-800.zip)
 x264-snapshot-20131129-2245-stable.tar.bz2 (core.138)
 	for srs to support live stream transcoding.
+	remark: we use *.zip for all linux plantform.
 
 tools/ccache-3.1.9.zip
 	to fast build.
@@ -32,5 +34,8 @@ links:
 		http://217.20.164.161/~tipok/aacplus/libaacplus-2.0.2.tar.gz
 	aacplus-patch: 
 		http://www.3gpp.org/DynaReport/26410.htm 
-		http://www.3gpp.org/ftp/Specs/archive/26_series/26.410/26410-b00.zip
+		http://www.3gpp.org/ftp/Specs/archive/26_series/26.410/26410-800.zip
+	yasm:
+		http://yasm.tortall.net/
+		http://www.tortall.net/projects/yasm/releases/yasm-1.2.0.tar.gz
 

@@ -52,11 +52,10 @@ if [ $SRS_HLS = YES ]; then
     else
         echo "build nginx-1.5.7"; 
         (
-            pwd_dir=`pwd` &&
             rm -rf ${SRS_OBJS}/nginx-1.5.7 && cd ${SRS_OBJS} && 
             unzip -q ../3rdparty/nginx-1.5.7.zip && cd nginx-1.5.7 && 
             ./configure --prefix=`pwd`/_release && make && make install &&
-            ln -sf ${pwd_dir}/nginx-1.5.7/_release nginx
+            cd .. && ln -sf nginx-1.5.7/_release nginx
         )
     fi
     # check status
@@ -94,11 +93,10 @@ if [ $SRS_FFMPEG = YES ]; then
     else
         echo "build ffmpeg-2.1"; 
         (
-            pwd_dir=`pwd` && exit 0;
-            rm -rf ${SRS_OBJS}/nginx-1.5.7 && cd ${SRS_OBJS} && 
-            unzip -q ../3rdparty/nginx-1.5.7.zip && cd nginx-1.5.7 && 
-            ./configure --prefix=`pwd`/_release && make && make install &&
-            ln -sf ${pwd_dir}/nginx-1.5.7/_release nginx
+            cd ${SRS_OBJS} && pwd_dir=`pwd` && 
+            rm -rf ffmepg.src && mkdir -p ffmpeg.src && cd ffmpeg.src &&
+            rm -f build_ffmpeg.sh && ln -sf ../../auto/build_ffmpeg.sh && . build_ffmpeg.sh &&
+            cd ${pwd_dir} && ln -sf ffmepg.src/_release ffmpeg
         )
     fi
     # check status