-NEW_REVISION="#define FFMPEG_VERSION \"SVN-r$svn_revision\""
-OLD_REVISION=`cat version.h 2> /dev/null`
+# no revision number found
+test "$revision" || revision=$(cd "$1" && cat RELEASE 2> /dev/null)
+
+# releases extract the version number from the VERSION file
+version=$(cd "$1" && cat VERSION 2> /dev/null)
+test "$version" || version=$revision
+
+test -n "$3" && version=$version-$3
+
+if [ -z "$2" ]; then
+ echo "$version"
+ exit
+fi
+
+NEW_REVISION="#define LIBAV_VERSION \"$version\""
+OLD_REVISION=$(cat version.h 2> /dev/null)