We're currently testing live streaming to YouTube for in-house webinars. In the testing setup, we have a camera going to an HDMI splitter, and then the HDMI feeds going to two transcoding boxes. The primary box uploads to YouTube via a public IP (so it bypasses all firewall, proxy, and internal Quality of service settings) and the secondary box uploads via a 4G mobile data connection (with a theoretical 40mbp/s upload).
The primary box uses rtmp://a.rtmp.youtube.com/live2 as the upload URL.
The secondary box uses rtmp://b.rtmp.youtube.com/live2?backup=1 as the upload URL.
Now, this works. Both transcoding boxes start streaming, the preview button in the Live Control Room is pressed and the source from the primary transcoder comes through fine. I can disconnect the primary transcoder, watch the buffer health drop down to 0 and then after some delay (may be a few seconds, may be a few minutes) the backup video feed kicks in. I've tried tweaking for interaction/less buffering and added delay, but there's always, always a few seconds of buffering.
Is this an officially supported way of using multiple feeds, or is this a workaround method only?