+// for sound() builtins
+#define CHANFLAG_RELIABLE 1
+
+// these define the "engine" channel namespace
+#define CHAN_MIN_AUTO -128
+#define CHAN_MAX_AUTO 0
+#define CHAN_MIN_SINGLE 1
+#define CHAN_MAX_SINGLE 127
+#define IS_CHAN_AUTO(n) ((n) >= CHAN_MIN_AUTO && (n) <= CHAN_MAX_AUTO)
+#define IS_CHAN_SINGLE(n) ((n) >= CHAN_MIN_SINGLE && (n) <= CHAN_MAX_SINGLE)
+#define IS_CHAN(n) (IS_CHAN_AUTO(n) || IS_CHAN_SINGLE(n))
+
+// engine channel == network channel
+#define CHAN_ENGINE2NET(c) (c)
+#define CHAN_NET2ENGINE(c) (c)
+
+// engine view of channel encodes the auto flag into the channel number (see CHAN_ constants below)
+// user view uses the flags bitmask for it
+#define CHAN_USER2ENGINE(c) (c)
+#define CHAN_ENGINE2USER(c) (c)
+#define CHAN_ENGINE2CVAR(c) (abs(c))
+