PTZOptics Link 4K SRT setup: send SRT to Callaba Gateway
More live video workflow notes and product updates.
Written by Iurii Pakholkov
Founder of Callaba. Building cloud video tools for SRT, RTMP, WebRTC, NDI, live routing, monitoring, recording, and production workflows.
Release: Callaba 8.4
PTZOptics Link 4K SRT setup is a direct camera-to-cloud contribution workflow: keep Link 4K at the venue, configure it as the SRT Caller, and receive the feed in Callaba. Use this setup when Link 4K is at the venue and Callaba is the cloud SRT receiver for monitoring, recording, routing, multiview, or restreaming. The important preflight check is firmware: the unit should expose SRT settings in the PTZOptics web interface before you build the event around this path.
Quick answer
To use PTZOptics Link 4K with SRT, first confirm the firmware version and that the camera exposes SRT Caller or Listener settings. Then set Link 4K as the SRT Caller and send the stream to a cloud SRT Listener. In this guide, Callaba works as the SRT gateway, receiver, monitor, recorder, and routing layer. If the SRT menu is absent, update firmware first or use the confirmed RTMP/RTMPS fallback.
The camera sends one contribution feed into Callaba. After ingest, Callaba can preview, record, route, restream, and feed multiview in parallel, not as mandatory sequential setup steps.
- PTZOptics Link 4KSRT Caller at venue
- Callaba GatewaySRT Listener in cloud
- Preview
- Record
- Route
- Restream
- Multiview
What this setup does
In this workflow, Link 4K is the camera and encoder. Callaba is the SRT receiver/server in the cloud. After the SRT ingest connects, the same source can be used for operator preview, cloud recording, multiview, restreaming, or routing to other destinations. These are parallel downstream uses, not a required chain.
The primary path is direct SRT when the installed PTZOptics firmware exposes the SRT controls. RTMP/RTMPS is the first practical fallback for direct cloud delivery. RTSP is better treated as a local or bridge input unless your design specifically needs an RTSP pull workflow.
What this model can and cannot do in this workflow
For Link 4K, PTZOptics documentation lists IP streaming with SRT, RTSP, and RTMP. The Link 4K streaming page also documents two RTMP(S) streams and RTSP URLs, while the Gen 3 Web UI streaming documentation covers SRT settings for the product family that includes Link 4K.
- Confirmed useful outputs for this setup include RJ45/IP streaming, HDMI 2.0, 3G-SDI, USB 2.0, and Dante AV-H network video/audio.
- The SRT settings documented in the Gen 3 Web UI include enable, Caller/Listener mode, server, port, AES encryption, password, bandwidth overhead, latency, and optional Stream ID.
- Firmware changelogs for PT12X/20X/30X-LINK-4K list SRT Stream ID added to the web interface, so older units should be checked before an event.
- Compression standards in Link 4K technical specs include YUY2, MJPEG, H.264, and H.265. Start SRT tests with H.264 unless you have confirmed HEVC support across every downstream decoder or player.
- Audio is available through the camera audio path; newer Link 4K firmware notes mention G.711 audio encoding, while AAC appears in the streaming documentation context.
- Do not plan Link 4K as a native NDI source. The exact Link 4K technical specs I found do not list native NDI output or ST 2110.
- Link 4K is not a decoder. The direction here is camera to Callaba, not Callaba back to HDMI or SDI on the camera.
Public PTZOptics pages for this model are not all phrased the same way: SRT is listed in the Link 4K feature and Gen 3 Web UI materials, while the Link 4K streaming page focuses more on Dante AV-H, RTMP(S), and RTSP. I recommend confirming installed firmware and the visible SRT menu on the exact unit before the event.
Recommended workflow
Use Link 4K as the SRT Caller and Callaba as the cloud SRT Listener. This avoids inbound firewall work at the venue because the camera initiates the outbound UDP connection to Callaba.
Use Link 4K Listener mode only when you have a tested reason to reverse the direction. That design can require a public IP, UDP port forwarding, firewall rules, or a controlled NAT plan at the venue.
When not to use this setup
- If the camera and switcher are on the same LAN or in the same room, HDMI, 3G-SDI, USB, or Dante AV-H may be simpler than cloud ingest.
- If the only target is a public platform and you do not need cloud monitoring, routing, or recording, RTMP/RTMPS from the camera may be enough.
- If a production requires native NDI from the camera, choose a PTZOptics model that officially lists NDI. Do not assume Link 4K provides it.
- If SRT settings are missing on the installed firmware, update the unit first or use RTMP/RTMPS as the direct fallback.
Before you start
- Open the PTZOptics web interface and confirm the firmware version and SRT settings.
- Confirm outbound UDP from the venue to the Callaba server port.
- Use H.264 for the first test. For starting bitrates, try 4-6 Mb/s for 1080p30 or 6-8 Mb/s for 1080p60, then adjust to uplink and production needs.
- If GOP or keyframe interval is exposed, a 2 second keyframe interval is a practical first test.
- Stream ID and passphrase values are case-sensitive and whitespace-sensitive. A copied newline, trailing space, or changed capitalization can break the SRT handshake.
Create the Callaba ingest
In Callaba, create an SRT server and set it to listen on a UDP port reachable from the venue. If you use a Stream ID or passphrase, copy the values exactly. For the first test, keep the design simple: one camera, one Callaba SRT listener, and one preview window.
Success in Callaba means the SRT connection opens, incoming bitrate appears, uptime starts increasing, and preview/audio meters match the camera feed.
Configure Link 4K
In the PTZOptics Gen 3 Web UI, open the streaming settings area and enable SRT. Set the camera to Caller, enter the Callaba host or IP as the server, and use the UDP port from the Callaba SRT server. If encryption is used, match AES and password settings on both sides.
Use the Latency field in the SRT settings as an internet safety buffer. If you do not already know the network, start around 250-500 ms and lower it only after Callaba shows stable RTT, packet loss, and retransmit behavior. PTZOptics does not publish a public SRT library version for Link 4K in the materials I found; if handshake failures are hard to diagnose, confirm device firmware with PTZOptics support and check Callaba server build information or support notes for SRT compatibility.
Settings table
| Where | What to do / field to fill | First-test value | Why / check |
|---|---|---|---|
| Callaba | Create SRT server and choose UDP port | Any open UDP port allowed by firewall | Callaba waits for the camera connection. |
| Link 4K Web UI | SRT Enable | On | The camera must expose and enable SRT. |
| Link 4K Web UI | Mode | Caller | Best default for venue-to-cloud contribution. |
| Link 4K Web UI | Server | Callaba public IP or DNS name | Points the camera to the cloud receiver. |
| Link 4K Web UI | Port | Callaba SRT server UDP port | Must match the Callaba listener. |
| Link 4K Web UI | AES encryption | Match Callaba | AES mismatch prevents connection. |
| Link 4K Web UI | Password | Exact Callaba passphrase | Case and whitespace must match exactly. |
| Link 4K Web UI | Stream ID | Exact value, if required | Useful for routing one listener to the right source. |
Monitoring
Watch Callaba for incoming bitrate, connection uptime, RTT, packet loss, retransmits, preview video, and audio meters. If the stream connects but preview is black, check codec, resolution, and whether the encoder is actually sending frames. If audio meters are flat, check the Link 4K audio source and encoding settings before changing SRT settings.
Failover and local ingest options
For production events, plan what happens if the main encoder, venue uplink, or primary contribution path fails. Callaba can be part of that continuity plan without changing the basic PTZOptics Link 4K ingest workflow.
Recording and playback
Once ingest is stable, recording and playback can run from the same received source. You do not need to choose between preview, record, restream, and route as separate camera outputs. Keep a short test recording before the event and play it back to confirm video cadence, audio, and downstream decoder compatibility, especially if you move from H.264 to H.265.
Troubleshooting
| Symptom | Check in Callaba | Check on Link 4K | Likely fix |
|---|---|---|---|
| No SRT connection | Listener is running, UDP port is open, logs show no rejected Stream ID | SRT enabled, Caller mode, correct server and port | Fix firewall/NAT, port, Stream ID, or mode mismatch. |
| Handshake fails with encryption | Passphrase and AES policy | Password field and AES setting | Retype values manually; remove trailing spaces or copied newlines. |
| Connected but unstable | RTT, packet loss, retransmits, incoming bitrate | Latency field, bitrate, venue uplink | Raise SRT latency, lower bitrate, or improve uplink. |
| Video but no audio | Audio meters and recording playback | Audio input/source and audio encoding | Confirm line input, levels, and supported audio codec. |
| SRT menu missing | Use RTMPS ingest if needed | Firmware version and available streaming menus | Update firmware or use RTMP/RTMPS fallback. |
| RTSP fallback does not match examples | Bridge receives the RTSP source before sending to Callaba | Use the RTSP URL shown in the camera Web UI | Do not rely on copied RTSP examples; confirm the exact URL on the unit. |
Official references
Useful sources for confirming model behavior and settings:
Vendor references
- PTZOptics Link 4K product page
- PTZOptics Link 4K features
- PTZOptics Link 4K streaming
- PTZOptics Link 4K technical specs
- PTZOptics Gen 3 Web UI streaming settings
- PTZOptics firmware changelog
Protocol references
Callaba resources
FAQ
Can PTZOptics Link 4K send SRT directly to Callaba?
Yes, when the installed firmware exposes the SRT settings. Use Link 4K as Caller and Callaba as the cloud Listener.
What if the SRT menu is missing on Link 4K?
Update firmware first. If you cannot update before the event, use the confirmed RTMP/RTMPS path or an RTSP bridge only when that bridge is part of your design.
Should I use Link 4K SRT Caller or Listener mode?
Use Caller for most venue-to-cloud jobs. Listener mode means the venue side must accept inbound UDP, which can require port forwarding and firewall changes.
Does Link 4K support native NDI output?
Do not plan Link 4K as a native NDI source. The exact Link 4K technical specs I found list Dante AV-H and common physical/IP outputs, but not native NDI.
Can I use H.265 with this workflow?
Link 4K technical specs list H.265, but H.264 is the safer first test. Use H.265 only after confirming downstream player, decoder, recording, and restreaming support.
Is RTMPS a good fallback?
Yes. The Link 4K streaming documentation describes RTMP(S) streaming, including two streams. Use it when SRT is not available or when the destination expects RTMP(S).
Next steps
Create the Callaba SRT listener, confirm the Link 4K SRT menu, and run a short test with H.264 before the production day. Save the working firmware version, Stream ID, passphrase policy, port, and bitrate in the show documentation.
Try Callaba Gateway with PTZOptics Link 4K SRT
Create an SRT server in Callaba, send the device feed to the gateway, and check the received stream. After ingest is stable, use Callaba outputs for preview, recording, restreaming, multiview, playback, routing, or API workflows as parallel downstream options.