files/en-us/web/api/managedmediasource/startstreaming_event/index.md
{{APIRef("Media Source Extensions")}}{{AvailableInWorkers("window_and_dedicated")}}
The startstreaming event of the {{domxref("ManagedMediaSource")}} interface is fired when the {{domxref("ManagedMediaSource.streaming", "streaming")}} property changes from false to true. This indicates that the user agent needs more data to ensure uninterrupted playback, and the application should begin fetching and appending media segments.
Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}}, or set an event handler property.
addEventListener("startstreaming", (event) => {});
onstartstreaming = (event) => {};
A generic {{domxref("Event")}}.
This example creates a {{domxref("ManagedMediaSource")}}, attaches it to a {{htmlelement("video")}} element, and uses the startstreaming event to begin fetching and appending media data.
const videoUrl =
"https://mdn.github.io/shared-assets/videos/flower-fragmented.mp4";
const mediaType = 'video/mp4; codecs="avc1.64001F, mp4a.40.2"';
if (ManagedMediaSource.isTypeSupported(mediaType)) {
const video = document.createElement("video");
const source = new ManagedMediaSource();
video.controls = true;
video.disableRemotePlayback = true;
video.src = URL.createObjectURL(source);
document.body.appendChild(video);
source.addEventListener("sourceopen", () => {
const sourceBuffer = source.addSourceBuffer(mediaType);
source.addEventListener("startstreaming", async () => {
console.log("startstreaming — fetching media data");
const response = await fetch(videoUrl);
const data = await response.arrayBuffer();
sourceBuffer.appendBuffer(data);
});
});
}
{{Specifications}}
{{Compat}}