Handle Live Stream Disconnects

How Mux handles disconnects

Before reading this guide, you created and set up a Live Stream by following these steps:

• You have connected your encoder (for example OBS, Wirecast, your live streaming app) to an RTMP ingest server as covered in this guide: Configure Broadcast Software).
• Mux sends the video.live_stream.connected event to your environment.
• When the encoder starts sending media to the ingest server, the webhook events video.live_stream.recording and then video.live_stream.active are delivered to your environment.

If everything goes smoothly, the encoder will keep sending media and the server will keep processing it, creating video segments and updating the HLS playlists with new pieces of video (to understand in a how this works read Reduce live stream latency). Since all of this streaming is happening live, the ingest server needs to know what it should do when the encoder disconnects unexpectedly.

What happens when the live stream disconnects either intentionally or due to a drop in the network? Mux sends the video.live_stream.disconnected event for the live stream to your environment. This is where the reconnect_window comes into play.

Reconnect windows

When you create a Mux Live Stream assetAPI, the live stream object keys include a parameter called reconnect_window in the Request JSON.

The Reconnect Window is the time in seconds that Mux should wait for the streaming software to reconnect before considering the live stream finished and completing the recorded asset. As a default, Mux sets reconnect_window to 60 seconds, but this can be adjusted to any value between 0.1 to 1800 seconds.

How to handle reconnects from the Player/Client side

When a live stream disconnects, outcome depends on whether the encoder can reconnect before the reconnect window expires. There are two possible scenarios.

In scenario 1, the encoder re-connects

The ingest server will wait for the duration of the reconnect_window before it ends the live stream. While the encoder is disconnected, media is no longer being sent, so the HLS playlists are not getting new segments of video.

If the encoder reconnects before the reconnect_window expires then the HLS playlist will resume appending new video segments to the live stream.

In scenario 2, the Encoder expires

The following events will occur when the reconnect window expires:

1. Mux writes an EXT-X-ENDLIST tag to the HLS playlist. According to the HLS specification: EXT-X-ENDLIST: Indicates that no more media files will be added to the playlist file. This tells the player this stream is over and no more media is coming. Your player should emit an ended event, or something equivalent.

2. The live stream will transition from active back to idle

3. Mux will create a new asset. The active_asset_id while the live stream was active will be finalized. If the same live stream goes live again at a later time, then the live stream will get a new active_asset_id and a new asset will be created.

Reconnect windows and reduced latency

When streaming either with "latency_mode": "reduced" or "latency_mode": "low" BETA on your live stream, reconnect windows are automatically disabled. This means that as soon as a disconnect happens the HLS playlist will be ended with the EXT-X-ENDLIST tag and the asset will be finalized. If a reconnect happens after that, you will need to reload the source in your player and Mux will start creating a new asset.

If you are using lower latency options this is one of the tradeoffs to consider. Read more in the Live Stream Latency Guide about Reduced and Low Latency.