Multistreaming with castr.io

Before you start

Multistreaming with castr.io runs through the Castr service rather than only on your local device. You send one RTMP stream to Castr, and Castr forwards it to the destinations you select. You need a Castr account with multistreaming available, a stream key or server URL from Castr, and an encoder or streaming app that can send RTMP. For each destination, prepare the stream key and RTMP URL supplied by that platform. If the destination uses a scheduled stream, create the schedule or live event there first if the platform requires it.

Step-by-step instructions

Log in to Castr and open the multistream section. Create a new multistream project or select an existing one. Copy the RTMP server URL and stream key shown for the project.

Open your encoder or streaming software and add Castr as the output. Use the copied server URL and stream key. Keep the encoder set to a supported video format, such as H.264 with AAC audio, and start the stream.

Return to Castr and add each destination to the multistream project. Choose the platform from the available options and enter the destination stream key and RTMP URL. Save the destinations before going live to avoid missing a platform at the start.

Review the resolution and bitrate settings in the project. Castr may offer transcoding, but the exact options depend on your plan. Match the settings to your upload speed and the requirements of your destinations. If you need to stop or change a destination, remove or disable it in the project without stopping the encoder feed.

Check the output

While the encoder is sending to Castr, check the project dashboard for an active incoming signal. Open each destination in its own app or site and confirm that the stream appears. Watch for delayed audio, frozen video, or a destination showing offline even though the incoming stream is healthy. Some destinations may add a longer delay than others. If a platform applies its own transcoding, the final resolution may differ from the encoder output.

Common problems and next steps

If a destination does not receive the stream, check that its stream key and RTMP URL were entered without extra spaces. Replace keys that the destination marks as used or expired. If the encoder cannot connect to Castr, test the upload path and reduce the bitrate if your connection is unstable. A destination may reject a nonstandard resolution or unsupported audio format, so try a common setting such as 1080p or 720p at 30 frames per second with AAC audio.

When video and audio drift apart, stop the encoder output and start it again rather than editing individual destinations. If a platform requires a scheduled event, confirm that the event exists and that its start time is not blocking the incoming stream. After changing keys or destinations, restart the affected stream only if Castr requires it; otherwise, save the change and verify the destination again.