Covers the Magewell Ultra Encode family and the Ultra Stream family.
Which one you have matters:
Ultra Stream is the simpler consumer-facing product and supports RTMP and RTMPS only. If you have an Ultra Stream and need SRT, you need different hardware — skip to the RTMP section, which works perfectly well.
In Recast for Business, open Stream Inputs and choose + Stream Input. Pick RTMP or SRT — the choice is fixed once the input is created.
Recast then shows the values your encoder needs. Copy them from there rather than retyping them:
Note that an SRT input labels its credential STREAM ID, not Stream Key. It is the same value, under the name SRT uses for it.
Then confirm all three of these, or your stream will be refused:
A new stream input is switched off. Recast switches it on only when it is attached to a live, non-draft video.
Configure the unit through its web interface. Both families expose one over the network, and on some models over a USB or wifi connection as well.
Use no more than 50% of your measured upload bandwidth.
Encode in H.264, not H.265. Ultra Encode supports H.265 and NDI HX, and H.265 is tempting on a constrained uplink, but Mux's live ingest expects H.264. Set the codec explicitly rather than trusting a preset.
Which URL? Recast displays rtmp://global-live.mux.com:5222/app as your RTMP STREAM URL, and that works. This guide uses rtmps:// on port 443 instead: it is the same Mux ingest wrapped in TLS, so your stream key is not sent in clear text, and port 443 passes through restrictive venue networks that block port 5222. Use whichever your encoder supports.
Works on both Ultra Encode and Ultra Stream.
rtmps://global-live.mux.com:443/appBoth families support RTMPS, so use the rtmps:// URL on port 443. European users can substitute eu-west.live.mux.com.
Ultra Encode only. Ultra Stream does not support SRT.
global-live.mux.com6001500 msKey length must be 16, meaning 128-bit. Mux requires it. Magewell exposes this as a key-length value where 16 is AES-128, 24 is AES-192 and 32 is AES-256. Choosing 32 fails the handshake with an unhelpful error, and it is the most common SRT mistake.
Ultra Encode runs many sessions at once. It supports several simultaneous SRT caller and listener sessions plus RTMP destinations. That flexibility is useful and it is also a trap: every active session shares your uplink, so the 50% bandwidth headroom rule applies to the total.
Recording and streaming together. Where the unit records to SD or USB while streaming, a slow card can affect the whole pipeline. Use a fast card, or record elsewhere.
Ultra Stream is deliberately simple. It targets non-technical users and hides much of the encoder configuration. If you cannot find a setting from the table above, the device is probably choosing it for you — set what you can and accept the defaults for the rest.
Do not chase low latency. Recast streams run at standard latency (20–30 seconds) by design.
One protocol per stream input. A Recast stream input is created as either RTMP or SRT and cannot be switched afterwards.
Check the stream input is attached to a video and that the video is not a draft. The unit will report a healthy stream while Recast rejects it.
Then wait a full 30 seconds before concluding anything.
Usually bandwidth, especially if several sessions are active. Disable the other destinations and see whether Recast stabilises.
You have 30 minutes to reconnect before Recast treats the stream as ended.
Reduce the bitrate or drop a tier. Then check whether the unit is also recording to a slow card, which can starve the encoder.
Confirm AAC-LC at 48 kHz stereo and that the correct audio source is selected — embedded HDMI or SDI audio, or an analogue input.
Prefer embedded audio so audio and video share a clock.
Include the exact model (Ultra Encode or Ultra Stream, and which variant), the firmware version, the protocol, how many destinations are active, and your bitrate and resolution.
More detail: Recast live ingest reference
