add CF_MEDIA_PAUSE channel flag to allow waiting for IO before media codec is ready

This could be used at endpoints where signalling and media negotiated separately like in H323

src/include/switch_types.h

@@ -1362,6 +1362,7 @@ typedef enum {
 	CF_VIDEO_ECHO,
 	CF_SLA_INTERCEPT,
 	CF_VIDEO_BREAK,
+	CF_MEDIA_PAUSE,
 	/* WARNING: DO NOT ADD ANY FLAGS BELOW THIS LINE */
 	/* IF YOU ADD NEW ONES CHECK IF THEY SHOULD PERSIST OR ZERO THEM IN switch_core_session.c switch_core_session_request_xml() */
 	CF_FLAG_MAX

src/switch_core_io.c

@@ -26,6 +26,7 @@
  * Anthony Minessale II <anthm@freeswitch.org>
  * Michael Jerris <mike@jerris.com>
  * Paul D. Tinsley <pdt at jackhammer.org>
+ * Seven Du <dujinfang@gmail.com>
  *
  *
  * switch_core_io.c -- Main Core Library (Media I/O)
@@ -45,6 +46,10 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_write_video_frame(switch_cor
 		return SWITCH_STATUS_FALSE;
 	}
 
+	if (switch_channel_test_flag(session->channel, CF_MEDIA_PAUSE)) {
+		return SWITCH_STATUS_SUCCESS;
+	}
+
 	if (session->endpoint_interface->io_routines->write_video_frame) {
 		if ((status = session->endpoint_interface->io_routines->write_video_frame(session, frame, flags, stream_id)) == SWITCH_STATUS_SUCCESS) {
 			for (ptr = session->event_hooks.video_write_frame; ptr; ptr = ptr->next) {
@@ -69,6 +74,12 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_read_video_frame(switch_core
 		return SWITCH_STATUS_FALSE;
 	}
 
+	if (switch_channel_test_flag(session->channel, CF_MEDIA_PAUSE)) {
+		*frame = &runtime.dummy_cng_frame;
+		switch_yield(20000);
+		return SWITCH_STATUS_SUCCESS;
+	}
+
 	if (session->endpoint_interface->io_routines->read_video_frame) {
 		if ((status = session->endpoint_interface->io_routines->read_video_frame(session, frame, flags, stream_id)) == SWITCH_STATUS_SUCCESS) {
 			for (ptr = session->event_hooks.video_read_frame; ptr; ptr = ptr->next) {
@@ -165,6 +176,14 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_read_frame(switch_core_sessi
 			*frame = &runtime.dummy_cng_frame;
 			return SWITCH_STATUS_SUCCESS;
 		}
+
+		if (switch_channel_test_flag(session->channel, CF_MEDIA_PAUSE)) {
+			switch_yield(20000);
+			*frame = &runtime.dummy_cng_frame;
+			// switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_ERROR, "Media Paused!!!!\n");
+			return SWITCH_STATUS_SUCCESS;
+		}
+
 		switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_ERROR, "%s has no read codec.\n", switch_channel_get_name(session->channel));
 		switch_channel_hangup(session->channel, SWITCH_CAUSE_INCOMPATIBLE_DESTINATION);
 		return SWITCH_STATUS_FALSE;
@@ -1033,6 +1052,10 @@ SWITCH_DECLARE(switch_status_t) switch_core_session_write_frame(switch_core_sess
 		}
 	}
 
+	if (switch_channel_test_flag(session->channel, CF_MEDIA_PAUSE)) {
+		return SWITCH_STATUS_SUCCESS;
+	}
+
 	if (!(session->write_codec && switch_core_codec_ready(session->write_codec)) && !pass_cng) {
 		switch_log_printf(SWITCH_CHANNEL_SESSION_LOG(session), SWITCH_LOG_ERROR, "%s has no write codec.\n", switch_channel_get_name(session->channel));
 		switch_channel_hangup(session->channel, SWITCH_CAUSE_INCOMPATIBLE_DESTINATION);