static GOptionEntry entries[] = {{"peer-id", 0, 0, G_OPTION_ARG_STRING, &peer_id, "String ID of the peer to connect to", "ID"},{"server", 0, 0, G_OPTION_ARG_STRING, &server_url, "Signalling server to connect to", "URL"},{"disable-ssl", 0, 0, G_OPTION_ARG_NONE, &disable_ssl, "Disable ssl", NULL},{"remote-offerer", 0, 0, G_OPTION_ARG_NONE, &remote_is_offerer, "Request that the peer generate the offer and we'll answer", NULL},{NULL},
};

/* 连接到信令服务器。这是其他一切的入口点 */
static const gchar *server_url = "wss://webrtc.nirbheek.in:8443";static void
connect_to_websocket_server_async(void)
{SoupLogger *logger;SoupMessage *message;SoupSession *session;const char *https_aliases[] = {"wss", NULL};session = soup_session_new_with_options(SOUP_SESSION_SSL_STRICT, !disable_ssl,SOUP_SESSION_SSL_USE_SYSTEM_CA_FILE, TRUE,//SOUP_SESSION_SSL_CA_FILE, "/etc/ssl/certs/ca-bundle.crt",SOUP_SESSION_HTTPS_ALIASES, https_aliases, NULL);logger = soup_logger_new(SOUP_LOGGER_LOG_BODY, -1);soup_session_add_feature(session, SOUP_SESSION_FEATURE(logger));g_object_unref(logger);message = soup_message_new(SOUP_METHOD_GET, server_url);g_print("Connecting to server...\n");/* Once connected, we will register */soup_session_websocket_connect_async(session, message, NULL, NULL, NULL, (GAsyncReadyCallback)on_server_connected, message);app_state = SERVER_CONNECTING;
}

static void
on_server_connected(SoupSession *session, GAsyncResult *res,SoupMessage *msg)
{GError *error = NULL;ws_conn = soup_session_websocket_connect_finish(session, res, &error);if (error){cleanup_and_quit_loop(error->message, SERVER_CONNECTION_ERROR);g_error_free(error);return;}g_assert_nonnull(ws_conn);app_state = SERVER_CONNECTED;g_print("Connected to signalling server\n");g_signal_connect(ws_conn, "closed", G_CALLBACK(on_server_closed), NULL);g_signal_connect(ws_conn, "message", G_CALLBACK(on_server_message), NULL);/* Register with the server so it knows about us and can accept commands */register_with_server();
}

static gboolean
register_with_server(void)
{gchar *hello;gint32 our_id;if (soup_websocket_connection_get_state(ws_conn) !=SOUP_WEBSOCKET_STATE_OPEN)return FALSE;our_id = g_random_int_range(10, 10000);g_print("Registering id %i with server\n", our_id);app_state = SERVER_REGISTERING;// 使用随机整数 ID 向服务器注册。回复将通过 on_server_message() 接收hello = g_strdup_printf("HELLO %i", our_id);soup_websocket_connection_send_text(ws_conn, hello);g_free(hello);return TRUE;
}

static gboolean
setup_call(void)
{gchar *msg;if (soup_websocket_connection_get_state(ws_conn) != SOUP_WEBSOCKET_STATE_OPEN)return FALSE;if (!peer_id)return FALSE;g_print("Setting up signalling server call with %s\n", peer_id);app_state = PEER_CONNECTING;msg = g_strdup_printf("SESSION %s", peer_id);soup_websocket_connection_send_text(ws_conn, msg);g_free(msg);return TRUE;
}

/* One mega message handler for our asynchronous calling mechanism */
static void
on_server_message(SoupWebsocketConnection *conn, SoupWebsocketDataType type,GBytes *message, gpointer user_data)
{// 检测数据是否为文本类型gchar *text;switch (type) {case SOUP_WEBSOCKET_DATA_BINARY:g_printerr("Received unknown binary message, ignoring\n");return;case SOUP_WEBSOCKET_DATA_TEXT: {gsize size;const gchar *data = g_bytes_get_data(message, &size);/* Convert to NULL-terminated string */text = g_strndup(data, size);break;}default:g_assert_not_reached();}// 服务器已接受我们的注册，我们已准备好发送命令if (g_strcmp0(text, "HELLO") == 0) {if (app_state != SERVER_REGISTERING) {cleanup_and_quit_loop("ERROR: Received HELLO when not registering", APP_STATE_ERROR);goto out;}app_state = SERVER_REGISTERED;g_print("Registered with server\n");// 要求信令服务器将我们与特定对等点连接起来if (!setup_call()) {cleanup_and_quit_loop("ERROR: Failed to setup call", PEER_CALL_ERROR);goto out;}/* Call has been setup by the server, now we can start negotiation */} else if (g_strcmp0(text, "SESSION_OK") == 0) {if (app_state != PEER_CONNECTING) {cleanup_and_quit_loop("ERROR: Received SESSION_OK when not calling", PEER_CONNECTION_ERROR);goto out;}app_state = PEER_CONNECTED;// 开始谈判（交换 SDP 和 ICE 候选人）if (!start_pipeline())cleanup_and_quit_loop("ERROR: failed to start pipeline", PEER_CALL_ERROR);} else if (g_str_has_prefix(text, "ERROR")) {  //处理错误消息switch (app_state) {case SERVER_CONNECTING:app_state = SERVER_CONNECTION_ERROR;break;case SERVER_REGISTERING:app_state = SERVER_REGISTRATION_ERROR;break;case PEER_CONNECTING:app_state = PEER_CONNECTION_ERROR;break;case PEER_CONNECTED:case PEER_CALL_NEGOTIATING:app_state = PEER_CALL_ERROR;break;default:app_state = APP_STATE_ERROR;}cleanup_and_quit_loop(text, 0);/* Look for JSON messages containing SDP and ICE candidates */} else {JsonNode *root;JsonObject *object, *child;JsonParser *parser = json_parser_new();if (!json_parser_load_from_data(parser, text, -1, NULL)){g_printerr("Unknown message '%s', ignoring", text);g_object_unref(parser);goto out;}root = json_parser_get_root(parser);if (!JSON_NODE_HOLDS_OBJECT(root)){g_printerr("Unknown json message '%s', ignoring", text);g_object_unref(parser);goto out;}object = json_node_get_object(root);if (json_object_has_member(object, "sdp")) { //远端的sdp消息int ret;GstSDPMessage *sdp;const gchar *text, *sdptype;GstWebRTCSessionDescription *answer;g_assert_cmphex(app_state, ==, PEER_CALL_NEGOTIATING);child = json_object_get_object_member(object, "sdp");if (!json_object_has_member(child, "type")) {cleanup_and_quit_loop("ERROR: received SDP without 'type'", PEER_CALL_ERROR);goto out;}sdptype = json_object_get_string_member(child, "type");// 在这个例子中，我们默认创建了要约并收到一个答案，但可以注释掉要约创建并等待要约，因此我们在这里处理。// 请参阅 gst-plugins-bad 中的 tests/examples/webrtcbidirectional.c 以获取另一个示例，了解如何处理来自同行的要约并使用 webrtcbin 回复答案。 text = json_object_get_string_member(child, "sdp");ret = gst_sdp_message_new(&sdp);g_assert_cmphex(ret, ==, GST_SDP_OK);ret = gst_sdp_message_parse_buffer((guint8 *)text, strlen(text), sdp);g_assert_cmphex(ret, ==, GST_SDP_OK);if (g_str_equal(sdptype, "answer")){ // answer sdp消息g_print("Received answer:\n%s\n", text);answer = gst_webrtc_session_description_new(GST_WEBRTC_SDP_TYPE_ANSWER, sdp);g_assert_nonnull(answer);// 设置远端的sdp到pipeline{GstPromise *promise = gst_promise_new();g_signal_emit_by_name(webrtc1, "set-remote-description", answer, promise);gst_promise_interrupt(promise);gst_promise_unref(promise);}app_state = PEER_CALL_STARTED;} else { // offer sdp消息g_print("Received offer:\n%s\n", text);on_offer_received(sdp);}} else if (json_object_has_member(object, "ice")) { // ICE候选人信息const gchar *candidate;gint sdpmlineindex;child = json_object_get_object_member(object, "ice");candidate = json_object_get_string_member(child, "candidate");sdpmlineindex = json_object_get_int_member(child, "sdpMLineIndex");/* Add ice candidate sent by remote peer */g_signal_emit_by_name(webrtc1, "add-ice-candidate", sdpmlineindex, candidate);} else {g_printerr("Ignoring unknown JSON message:\n%s\n", text);}g_object_unref(parser);}
out:g_free(text);
}

#define STUN_SERVER " stun-server=stun://stun.l.google.com:19302 "
#define RTP_CAPS_OPUS "application/x-rtp,media=audio,encoding-name=OPUS,payload="
#define RTP_CAPS_VP8 "application/x-rtp,media=video,encoding-name=VP8,payload="static gboolean
start_pipeline(void)
{GstStateChangeReturn ret;GError *error = NULL;pipe1 = gst_parse_launch("webrtcbin bundle-policy=max-bundle name=sendrecv " STUN_SERVER"videotestsrc is-live=true pattern=ball ! videoconvert ! queue ! vp8enc deadline=1 ! rtpvp8pay ! " "queue ! " RTP_CAPS_VP8 "96 ! sendrecv. " //发送视频"audiotestsrc is-live=true wave=red-noise ! audioconvert ! audioresample ! queue ! opusenc ! rtpopuspay ! ""queue ! " RTP_CAPS_OPUS "97 ! sendrecv. ", //发送音频&error);if (error) {g_printerr("Failed to parse launch: %s\n", error->message);g_error_free(error);goto err;}// 获取webrtcbin插件对象webrtc1 = gst_bin_get_by_name(GST_BIN(pipe1), "sendrecv");g_assert_nonnull(webrtc1);// 这是我们create offer sdp的 gstwebrtc 入口点。当管道进入播放状态时，它将被调用。g_signal_connect(webrtc1, "on-negotiation-needed", G_CALLBACK(on_negotiation_needed), NULL);// 我们需要通过 websockets 信令服务器将此 ICE 候选传输到浏览器。来自浏览器的传入 ice 候选也需要我们添加，请参阅 on_server_message()g_signal_connect(webrtc1, "on-ice-candidate", G_CALLBACK(send_ice_candidate_message), NULL);g_signal_connect(webrtc1, "notify::ice-gathering-state", G_CALLBACK(on_ice_gathering_state_notify), NULL);gst_element_set_state(pipe1, GST_STATE_READY);g_signal_emit_by_name(webrtc1, "create-data-channel", "channel", NULL, &send_channel);if (send_channel) {g_print("Created data channel\n");connect_data_channel_signals(send_channel);} else {g_print("Could not create data channel, is usrsctp available?\n");}g_signal_connect(webrtc1, "on-data-channel", G_CALLBACK(on_data_channel), NULL);// 接收到音视频数据on_incoming_stream回调函数处理g_signal_connect(webrtc1, "pad-added", G_CALLBACK(on_incoming_stream), pipe1);// 生命周期与管道本身相同, 启动管道gst_object_unref(webrtc1);g_print("Starting pipeline\n");ret = gst_element_set_state(GST_ELEMENT(pipe1), GST_STATE_PLAYING);if (ret == GST_STATE_CHANGE_FAILURE)goto err;return TRUE;
err:if (pipe1)g_clear_object(&pipe1);if (webrtc1)webrtc1 = NULL;return FALSE;
}

static void
connect_data_channel_signals(GObject *data_channel)
{g_signal_connect(data_channel, "on-error", G_CALLBACK(data_channel_on_error), NULL);g_signal_connect(data_channel, "on-open", G_CALLBACK(data_channel_on_open), NULL);g_signal_connect(data_channel, "on-close", G_CALLBACK(data_channel_on_close), NULL);g_signal_connect(data_channel, "on-message-string", G_CALLBACK(data_channel_on_message_string), NULL);
}

static void
on_negotiation_needed(GstElement *element, gpointer user_data)
{app_state = PEER_CALL_NEGOTIATING;// 是否接收远端的sdp，音视频流if (remote_is_offerer) { //发送指令获取sdpgchar *msg = g_strdup_printf("OFFER_REQUEST");soup_websocket_connection_send_text(ws_conn, msg);g_free(msg);} else {//只发送模式GArray *transceivers;g_signal_emit_by_name(element, "get-transceivers", &transceivers);GstWebRTCRTPTransceiver *transceiver = g_array_index(transceivers, GstWebRTCRTPTransceiver *, 0);transceiver->direction = GST_WEBRTC_RTP_TRANSCEIVER_DIRECTION_SENDONLY;g_object_set(transceiver, "fec-type", GST_WEBRTC_FEC_TYPE_ULP_RED, NULL);g_object_set(transceiver, "do-nack", TRUE, NULL);//创建本地offer sdp，获取本地音视频信息GstPromise *promise;promise = gst_promise_new_with_change_func(on_offer_created, user_data, NULL);g_signal_emit_by_name(webrtc1, "create-offer", NULL, promise);}
}

/* Offer created by our pipeline, to be sent to the peer */
static void
on_offer_created(GstPromise *promise, gpointer user_data)
{GstWebRTCSessionDescription *offer = NULL;const GstStructure *reply;g_assert_cmphex(app_state, ==, PEER_CALL_NEGOTIATING);g_assert_cmphex(gst_promise_wait(promise), ==, GST_PROMISE_RESULT_REPLIED);reply = gst_promise_get_reply(promise);gst_structure_get(reply, "offer", GST_TYPE_WEBRTC_SESSION_DESCRIPTION, &offer, NULL);gst_promise_unref(promise);promise = gst_promise_new();g_signal_emit_by_name(webrtc1, "set-local-description", offer, promise);gst_promise_interrupt(promise);gst_promise_unref(promise);/* Send offer to peer */send_sdp_to_peer(offer);gst_webrtc_session_description_free(offer);
}

static void
on_incoming_stream(GstElement *webrtc, GstPad *pad, GstElement *pipe)
{GstElement *decodebin;GstPad *sinkpad;if (GST_PAD_DIRECTION(pad) != GST_PAD_SRC)return;decodebin = gst_element_factory_make("decodebin", NULL);g_signal_connect(decodebin, "pad-added", G_CALLBACK(on_incoming_decodebin_stream), pipe);gst_bin_add(GST_BIN(pipe), decodebin);gst_element_sync_state_with_parent(decodebin);sinkpad = gst_element_get_static_pad(decodebin, "sink");gst_pad_link(pad, sinkpad);gst_object_unref(sinkpad);
}

static void
on_incoming_decodebin_stream(GstElement *decodebin, GstPad *pad,GstElement *pipe)
{GstCaps *caps;const gchar *name;if (!gst_pad_has_current_caps(pad)) {g_printerr("Pad '%s' has no caps, can't do anything, ignoring\n", GST_PAD_NAME(pad));return;}caps = gst_pad_get_current_caps(pad);name = gst_structure_get_name(gst_caps_get_structure(caps, 0));if (g_str_has_prefix(name, "video")){handle_media_stream(pad, pipe, "videoconvert", "autovideosink");} else if (g_str_has_prefix(name, "audio")) {handle_media_stream(pad, pipe, "audioconvert", "autoaudiosink");} else {g_printerr("Unknown pad %s, ignoring", GST_PAD_NAME(pad));}
}