function initCapture(api) {
      const captureSection = document.getElementById("capture");
      const clientIdElement = captureSection.querySelector(".client-id");
      const videoElement = captureSection.getElementsByTagName("video")[0];

      const listener = {
        connected: function(clientId) { clientIdElement.textContent = clientId; },
        disconnected: function() { clientIdElement.textContent = "none"; }
      };
      api.registerConnectionListener(listener);

      document.getElementById("capture-button").addEventListener("click", (event) => {
        event.preventDefault();

        if (captureSection._producerSession) {
          captureSection._producerSession.close();
        } else if (!captureSection.classList.contains("starting")) {
          captureSection.classList.add("starting");

          const constraints = {
            video: { width: 1280, height: 720 }
          };
          navigator.mediaDevices.getUserMedia(constraints).then((stream) => {
            const session = api.createProducerSession(stream);
            if (session) {
              captureSection._producerSession = session;

              session.addEventListener("error", (event) => {
                if (captureSection._producerSession === session) {
                  console.error(event.message, event.error);
                }
              });

              session.addEventListener("closed", () => {
                if (captureSection._producerSession === session) {
                  videoElement.pause();
                  videoElement.srcObject = null;
                  captureSection.classList.remove("has-session", "starting");
                  delete captureSection._producerSession;
                }
              });

              session.addEventListener("stateChanged", (event) => {
                if ((captureSection._producerSession === session) &&
                  (event.target.state === GstWebRTCAPI.SessionState.streaming)) {
                  videoElement.srcObject = stream;
                  videoElement.play().catch(() => {});
                  captureSection.classList.remove("starting");
                }
              });

              session.addEventListener("clientConsumerAdded", (event) => {
                if (captureSection._producerSession === session) {
                  console.info(`client consumer added: ${event.detail.peerId}`);
                }
              });

              session.addEventListener("clientConsumerRemoved", (event) => {
                if (captureSection._producerSession === session) {
                  console.info(`client consumer removed: ${event.detail.peerId}`);
                }
              });

              captureSection.classList.add("has-session");
              session.start();
            } else {
              for (const track of stream.getTracks()) {
                track.stop();
              }

              captureSection.classList.remove("starting");
            }
          }).catch((error) => {
            console.error("cannot have access to webcam and microphone", error);
            captureSection.classList.remove("starting");
          });
        }
      });
    }

    function initRemoteStreams(api) {
      const remoteStreamsElement = document.getElementById("remote-streams");

      const listener = {
        producerAdded: function(producer) {
          const producerId = producer.id
          if (!document.getElementById(producerId)) {
            remoteStreamsElement.insertAdjacentHTML("beforeend",
              `<li id="${producerId}">
                                <div class="button">${producer.meta.name || producerId}</div>
                                <div class="video">
                                    <div class="spinner">
                                        <div></div>
                                        <div></div>
                                        <div></div>
                                        <div></div>
                                    </div>
                                    <span class="remote-control">&#xA9;</span>
                                    <video></video>
                                    <div class="fullscreen"><span title="Toggle fullscreen">&#x25A2;</span></div>
                                </div>
                            </li>`);

            const entryElement = document.getElementById(producerId);
            const videoElement = entryElement.getElementsByTagName("video")[0];

            videoElement.addEventListener("playing", () => {
              if (entryElement.classList.contains("has-session")) {
                entryElement.classList.add("streaming");
              }
            });

            entryElement.addEventListener("click", (event) => {
              event.preventDefault();
              if (!event.target.classList.contains("button")) {
                return;
              }

              if (entryElement._consumerSession) {
                entryElement._consumerSession.close();
              } else {
                const session = api.createConsumerSession(producerId);
                if (session) {
                  entryElement._consumerSession = session;

                  session.addEventListener("error", (event) => {
                    if (entryElement._consumerSession === session) {
                      console.error(event.message, event.error);
                    }
                  });

                  session.addEventListener("closed", () => {
                    if (entryElement._consumerSession === session) {
                      videoElement.pause();
                      videoElement.srcObject = null;
                      entryElement.classList.remove("has-session", "streaming", "has-remote-control");
                      delete entryElement._consumerSession;
                    }
                  });

                  session.addEventListener("streamsChanged", () => {
                    if (entryElement._consumerSession === session) {
                      const streams = session.streams;
                      if (streams.length > 0) {
                        videoElement.srcObject = streams[0];
                        videoElement.play().catch(() => {});
                      }
                    }
                  });

                  session.addEventListener("remoteControllerChanged", () => {
                    if (entryElement._consumerSession === session) {
                      const remoteController = session.remoteController;
                      if (remoteController) {
                        entryElement.classList.add("has-remote-control");
                        remoteController.attachVideoElement(videoElement);
                      } else {
                        entryElement.classList.remove("has-remote-control");
                      }
                    }
                  });

                  entryElement.classList.add("has-session");
                  session.connect();
                }
              }
            });
          }
        },

        producerRemoved: function(producer) {
          const element = document.getElementById(producer.id);
          if (element) {
            if (element._consumerSession) {
              element._consumerSession.close();
            }

            element.remove();
          }
        }
      };

      api.registerProducersListener(listener);
      for (const producer of api.getAvailableProducers()) {
        listener.producerAdded(producer);
      }
    }

    window.addEventListener("DOMContentLoaded", () => {
      document.addEventListener("click", (event) => {
        if (event.target.matches("div.video>div.fullscreen:hover>span")) {
          event.preventDefault();
          event.target.parentNode.previousElementSibling.requestFullscreen();
        }
      });

      const signalingProtocol = window.location.protocol.startsWith("https") ? "wss" : "ws";
      const gstWebRTCConfig = {
        meta: { name: `WebClient-${Date.now()}` },
        signalingServerUrl: `ws://127.0.0.1:8443`,
      };

      const api = new GstWebRTCAPI(gstWebRTCConfig);
      // initCapture(api);
      initRemoteStreams(api);
    });