Add "prod" function, to get audio moving

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@856 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channel.c

@@ -726,6 +726,7 @@ int ast_activate_generator(struct ast_channel *chan, struct ast_generator *gen,
 		chan->generator->release(chan, chan->generatordata);
 		chan->generatordata = NULL;
 	}
+	ast_prod(chan);
 	if ((chan->generatordata = gen->alloc(chan, params))) {
 		chan->generator = gen;
 	} else {
@@ -1210,6 +1211,18 @@ static int do_senddigit(struct ast_channel *chan, char digit)
 	return 0;
 }
 
+int ast_prod(struct ast_channel *chan)
+{
+	struct ast_frame a = { AST_FRAME_VOICE };
+	char nothing[128];
+	/* Send an empty audio frame to get things moving */
+	if (chan->_state != AST_STATE_UP) {
+		a.subclass = chan->pvt->rawwriteformat;
+		a.data = nothing + AST_FRIENDLY_OFFSET;
+	}
+	return 0;
+}
+
 int ast_write(struct ast_channel *chan, struct ast_frame *fr)
 {
 	int res = -1;

include/asterisk/channel.h

@@ -462,6 +462,9 @@ struct ast_frame *ast_read(struct ast_channel *chan);
  */
 int ast_write(struct ast_channel *chan, struct ast_frame *frame);
 
+/* Send empty audio to prime a channel driver */
+int ast_prod(struct ast_channel *chan);
+
 //! Sets read format on channel chan
 /*! 
  * \param chan channel to change