Obtained from:	https://gitlab.xiph.org/xiph/icecast-libshout/commit/0ac7ed9e84c3871d4427acc1ce59dca5e4af21ef

--- include/shout/shout.h.in.orig	2019-05-22 09:05:32 UTC
+++ include/shout/shout.h.in
@@ -85,6 +85,11 @@ extern "C" {
 #define SHOUT_TLS_RFC2818           ( 11) /* Use TLS for transport layer like HTTPS [RFC2818] does. */
 #define SHOUT_TLS_RFC2817           ( 12) /* Use TLS via HTTP Upgrade:-header [RFC2817]. */
 
+/* Possible values for blocking */
+#define SHOUT_BLOCKING_DEFAULT      (255) /* Use the default blocking setting. */
+#define SHOUT_BLOCKING_FULL         (  0) /* Block in all I/O related functions */
+#define SHOUT_BLOCKING_NONE         (  1) /* Do not block in I/O related functions */
+
 #define SHOUT_AI_BITRATE            "bitrate"
 #define SHOUT_AI_SAMPLERATE         "samplerate"
 #define SHOUT_AI_CHANNELS           "channels"
@@ -244,7 +249,8 @@ int shout_set_protocol(shout_t *self, un
 unsigned int shout_get_protocol(shout_t *self);
 
 /* Instructs libshout to use nonblocking I/O. Must be called before
- * shout_open (no switching back and forth midstream at the moment). */
+ * shout_open (no switching back and forth midstream at the moment).
+ * nonblocking is one of SHOUT_BLOCKING_xxx. */
 int shout_set_nonblocking(shout_t* self, unsigned int nonblocking);
 unsigned int shout_get_nonblocking(shout_t *self);