Hello, I want to implement a sip client that sends early media (unidirectional video only), and once the call is established, sends video and audio but receives audio only.  The idea is to implement a doorbell with video. It's mostly working, except for early media, and I haven't been able to find any sample code for this. I thought I was supposed to do it in the on_call_state() callback: static void on_call_state(pjsua_call_id call_id, pjsip_event *e) {     pjsua_call_info ci;     pjsua_call_get_info(call_id, &ci);     if (ci.state == PJSIP_INV_STATE_EARLY) {         pjsua_call_vid_strm_op_param param;         pjsua_call_vid_strm_op_param_default(&param);         param.dir = PJMEDIA_DIR_ENCODING; /* send video only */         param.cap_dev = video_device_id;  /* video_device_id set somewhere else */         pjsua_conf_connect(ci.conf_slot, pjsua_call_get_conf_port(call_id));         unsigned i;         for (i = 0; i < ci.media_cnt; i++) {             if (ci.media[i].type == PJMEDIA_TYPE_VIDEO) {                 pj_status_t status;                 param.med_idx = i;                 pjsua_call_set_vid_strm(call_id, PJSUA_CALL_VID_STRM_START_TRANSMIT, &param);             }         }     } } But when ci.state == PJSIP_INV_STATE_EARLY, ci.media_cnt == 0. Any ideas or examples?