Datavideo NVS-40 SRT setup: send SRT to Callaba Gateway
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
Datavideo NVS-40 SRT setup is best treated as a direct contribution workflow: put the NVS-40 at the venue, select SRT Caller, and send H.264/AAC to a cloud SRT Listener in Callaba Gateway. Use this setup when NVS-40 is at the venue and Callaba is the cloud SRT receiver for monitoring, recording, routing, multiview, or restreaming. The NVS-40 can also stream RTMP/RTMPS, RTSP, HLS, and MPEG-TS, but this guide focuses on the native SRT path because Caller and Listener modes are documented for this model.
Quick answer
To use Datavideo NVS-40 with SRT, set NVS-40 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. Start without Stream ID or passphrase unless your installed NVS-40 firmware clearly exposes matching fields; then add security after ingest is stable.
The NVS-40 sends one SRT contribution feed into Callaba. After ingest, Callaba can preview, record, route, restream, and show the same source in multiview as parallel downstream uses, not as mandatory sequential setup steps.
- NVS-40SRT Caller, H.264/AAC
- Callaba GatewaySRT Listener
- Preview
- Record
- Route
- Restream
- Multiview
What this setup does
For an NVS-40 SRT gateway workflow, the NVS-40 is the field encoder. Callaba is the cloud SRT receiver, listener, and routing layer. This is the cleanest answer to searches such as NVS-40 SRT Caller, NVS-40 SRT to cloud, NVS-40 SRT receiver, and Datavideo NVS-40 SRT server: in the default cloud workflow, the practical server is Callaba, while the NVS-40 calls out to it.
The NVS-40 manual also describes SRT Listener mode. I treat that as an advanced fallback, not the first production choice, because it means the venue side must accept an inbound SRT connection. That can require a public IP address, UDP port forwarding, firewall rules, or a tested NAT traversal plan.
What this model can and cannot do in this workflow
The NVS-40 is a four-channel streaming encoder/recorder. Exact-model Datavideo specifications list four HDMI inputs, with channel 1 selectable between SDI and HDMI, one HDMI 1.4 program output, one SDI loop-through output, XLR and RCA audio inputs, Gigabit Ethernet, and recording to a 2.5-inch SSD/HDD in MP4, MOV, or TS.
- Confirmed for this setup: SRT, RTMP/RTMPS Publish, RTSP over HTTP/TCP/UDP, HLS, and TS over TCP/UDP are listed for the NVS-40.
- SRT roles: the manual documents SRT Caller and SRT Listener. Use Caller for the normal cloud contribution path into Callaba.
- Video and audio: official specifications list H.264/AVC High Profile Level 4.1 and AAC-LC audio at 48 kHz, 16-bit, with 128K, 256K, or 384K audio bitrate options.
- Input formats: the product specification includes up to 1080p60, plus 1080i, 720p, 576i, and 480i formats.
- Not confirmed for this model: do not plan the Datavideo NVS-40 as a native NDI source. Exact-model protocol lists reviewed for this guide do not list NDI, ST 2110, or HEVC/H.265.
- SRT security caveat: public NVS-40 manual text confirms Caller and Listener but does not clearly confirm Stream ID, passphrase, encryption fields, rendezvous mode, or the SRT library version. Confirm those details in the installed firmware UI or with Datavideo support before the event.
- RTMPS caveat: Datavideo states RTMPS support for NVS-40 was added in firmware version 1.5.8 or higher, so update and test before using RTMPS as a fallback.
- Close variant note: NVS-40D appears as a related drive or bundle variant in Datavideo listings. This page is for NVS-40; do not copy NVS-40D-only package or regional claims into an NVS-40 deployment unless the same firmware and manual apply.
Recommended workflow
Use this architecture when the NVS-40 is in the venue, truck, classroom, studio rack, or event site, and Callaba runs in a reachable cloud or data-center network. Feed cameras or a production switcher into the NVS-40 over HDMI, or use the channel 1 SDI input when appropriate. The NVS-40 encodes the program as H.264/AAC and sends SRT Caller traffic to a Callaba SRT Listener on a known public IP or DNS name and UDP port.
After Callaba receives the contribution, monitoring, recording, restreaming, routing, playback, and multiview are parallel downstream choices. Do not think of preview, recording, and routing as a serial chain. First make the ingest stable, then enable the outputs the production actually needs.
When not to use this setup
- If the switcher, monitor, and encoder are in the same rack and no cloud routing is needed, local SDI or HDMI may be simpler. NDI is not a native NVS-40 option.
- If the only destination is YouTube, Facebook, or another public platform and low-latency monitoring or cloud routing is not important, RTMP or RTMPS may be enough. Check that the NVS-40 firmware is RTMPS-capable before the event.
- If the job needs a return feed to SDI or HDMI at a remote site, use a decoder workflow. The NVS-40 is the encoder side, not the decoder side.
- If you want the NVS-40 to run as SRT Listener over the public internet, treat that as a controlled network design. The venue side must be reachable inbound on the correct UDP port.
Before you start
Confirm the NVS-40 firmware, the input format, the selected audio source, the uplink capacity, and the Callaba public IP or DNS name. Open the chosen UDP port in the cloud security group, host firewall, and any upstream network firewall. For a first internet test, I usually start with 250-500 ms SRT latency and a conservative H.264 bitrate, then adjust after checking RTT, packet loss, retransmits, and received bitrate.
If an SRT handshake fails in a way that does not match normal firewall or credential problems, confirm that both sides support compatible SRT major versions. On the NVS-40 side, use firmware release notes, the device system page if it exposes software details, or Datavideo support. On the Callaba side, use release notes, server build information, or support information.
Create the Callaba ingest
- Open Callaba and create an SRT server for this event feed.
- Set the Callaba side as the listener and choose a UDP port such as 10080 for the first test.
- Open that UDP port in the cloud and host firewall.
- Leave Stream ID and passphrase disabled for the first NVS-40 test unless your unit clearly exposes matching fields. If you use them, keep values case-sensitive and whitespace-sensitive.
- Start the SRT server and keep the Callaba stream status, event log, and preview page open.
Success looks like this: the Callaba server shows an active connection, incoming bitrate appears, connection uptime increases, preview displays video, and audio meters move when the source has audio.
Configure the NVS-40
- Connect the NVS-40 to the production network and open its web control interface from a computer on the same network.
- Open the Streaming page.
- Choose SRT in the Stream Type drop-down.
- Select Caller in the Streaming Type or mode drop-down.
- Enter the Callaba public IP address or DNS name in the Caller IP address field.
- Enter the Callaba UDP port in the SRT port number field.
- Apply the settings, then start streaming from the web UI or the front-panel stream control according to your operating habit.
Set the encode format to H.264 and keep audio as AAC-LC. For first tests, use a bitrate that matches the uplink rather than the maximum product specification. A practical start is 2.5-4 Mb/s for 720p, 4-6 Mb/s for 1080p30, and 6-8 Mb/s for 1080p60, then adjust for motion, venue bandwidth, and production quality requirements. If the firmware exposes GOP or keyframe interval, two seconds is a sensible first value for live distribution.
Settings table
| Where | What to do / field to fill | First-test value | Why / check |
|---|---|---|---|
| Callaba: SRT server creation | Create a listener and choose a UDP port | 10080 or another open UDP port | Callaba must be reachable from the venue network. |
| Callaba: SRT server latency | Set receive latency | 250-500 ms for internet testing | Lower later only after RTT, loss, and retransmits are stable. |
| Callaba: access/security settings | Stream ID and passphrase policy, if used | Disabled for the first test | NVS-40 public docs do not clearly confirm matching fields. If used, copy exactly; trailing spaces, newlines, or capitalization changes can break the handshake. |
| NVS-40 Streaming page | Stream Type drop-down | SRT | Selects the SRT output path instead of RTMP, RTSP, HLS, or TS. |
| NVS-40 SRT streaming area | Streaming Type or mode drop-down | Caller | Best default when the encoder is behind venue NAT and Callaba has the reachable listener. |
| NVS-40 SRT caller settings | Caller IP address | Callaba public IP or DNS name | Must point to the server that is listening for the stream. |
| NVS-40 SRT caller settings | SRT port number | Same UDP port as Callaba | A wrong or blocked UDP port usually produces no connection. |
| NVS-40 video encode settings | Video bitrate | Start below the measured uplink | Watch Callaba incoming bitrate, packet loss, RTT, and retransmits before increasing quality. |
Monitoring
In Callaba, watch incoming bitrate, connection uptime, RTT, packet loss, retransmits, preview, and audio meters. On the NVS-40, check that the selected input is valid, the stream is started, and the device is not showing error status. If the stream connects but quality is unstable, reduce the encoder bitrate before changing multiple other variables.
For multiview or operator confidence monitoring, use Callaba preview and multiview after ingest is stable. For routed outputs, add destinations one at a time so the contribution path remains easy to troubleshoot.
Recording and playback
The NVS-40 can record locally to a 2.5-inch SSD or HDD in MP4, MOV, or TS. Callaba can also record the received SRT feed in the cloud and make it available for playback or downstream workflows. These are separate recording choices. You can use local device recording for an on-site backup and Callaba recording for cloud review, clipping, routing, or post-event delivery.
Troubleshooting
| Symptom | Check in Callaba | Check on device | Likely fix |
|---|---|---|---|
| No SRT connection | Event log, listener status, no incoming bitrate | Caller IP address, SRT port number, stream started | Open the UDP port, correct IP/DNS, confirm Caller on NVS-40 and Listener on Callaba. |
| Connection starts then drops | RTT, packet loss, retransmits, uptime resets | Venue uplink, encoder bitrate, input stability | Raise SRT latency, lower bitrate, use a better network path, then test again. |
| Black preview with connection active | Incoming bitrate and preview status | Selected HDMI/SDI input, supported resolution, program output | Feed a supported format, confirm channel 1 SDI/HDMI selection, and restart the stream. |
| No audio | Audio meters and recording audio track | Embedded audio, XLR/RCA input selection, audio gain | Choose the intended audio source and confirm AAC-LC output. |
| Security-related handshake failure | Rejected attempts or no uptime after connect attempt | Whether NVS-40 firmware exposes Stream ID or passphrase fields | Disable security for the first test, or copy values exactly on both sides. Values are case-sensitive and whitespace-sensitive. |
| RTMPS fallback fails | RTMP/RTMPS ingest log if using RTMP instead of SRT | NVS-40 firmware version | Update to firmware 1.5.8 or higher for RTMPS support, then retest. |
| Handshake remains unexplained | Server build, release notes, support information | NVS-40 firmware notes or Datavideo support response | Confirm compatible SRT major versions and retry with one listener, one caller, one port, no Stream ID, and no passphrase. |
Official references
Use these resources to confirm model-specific settings before production.
Vendor references
- Datavideo NVS-40 product export PDF
- Datavideo NVS-40 product page
- Datavideo RTMPS support bulletin for streaming encoders
- Datavideo NVS-40 user manual mirror
Protocol references
- Haivision SRT documentation: encrypting SRT streams
- Haivision documentation: SRT access control and Stream ID behavior
Callaba resources
FAQ
How do I use Datavideo NVS-40 with SRT?
Create an SRT Listener in Callaba, then configure the NVS-40 as SRT Caller. Enter the Callaba public IP or DNS name and UDP port in the NVS-40 SRT caller settings, apply the configuration, and start the stream.
Should NVS-40 be SRT Caller or SRT Listener?
Use SRT Caller for the normal cloud workflow. NVS-40 SRT Listener mode is documented, but it is usually an advanced fallback because the venue-side encoder must accept an inbound internet connection.
Does Datavideo NVS-40 support NDI?
No exact-model NVS-40 protocol specification reviewed here lists NDI. Do not plan the NVS-40 as a native NDI source. Use HDMI or SDI locally, or use SRT, RTMP/RTMPS, RTSP, HLS, or TS where those protocols fit the job.
Where do I enter NVS-40 SRT Stream ID or passphrase?
The public manual text I used confirms SRT Caller and Listener but does not clearly confirm Stream ID or passphrase fields for NVS-40. If your firmware exposes those fields, match Callaba exactly. Stream ID and passphrase values are case-sensitive and whitespace-sensitive.
Can I use RTMP or RTMPS instead of SRT?
Yes. RTMP/RTMPS Publish is listed for the NVS-40, and Datavideo states that RTMPS support was added in firmware 1.5.8 or higher. Use RTMP/RTMPS when the destination is a public platform and SRT monitoring or routing is not required.
Does NVS-40 support HEVC/H.265 or 4K for this workflow?
No exact-model source reviewed here lists HEVC/H.265 for NVS-40. The documented video encoder is H.264/AVC High Profile Level 4.1, with input formats up to 1080p60.
Next steps
- Bench-test one NVS-40, one Callaba SRT Listener, one UDP port, and no SRT security fields.
- Confirm preview, incoming bitrate, audio meters, recording, and connection uptime.
- Document the final IP/DNS, UDP port, bitrate, latency, firmware version, and security values.
- Add Stream ID or passphrase only if the installed NVS-40 firmware exposes matching fields and the production needs them.
- After ingest is stable, add recording, multiview, routing, restreaming, playback, or API automation as separate downstream tasks.
Try Callaba Gateway with Datavideo NVS-40 SRT setup
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.