Datavideo NVS-35 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
Use this Datavideo NVS-35 SRT setup when the NVS-35 is at the venue and Callaba is the cloud SRT receiver for monitoring, recording, routing, multiview, or restreaming. The NVS-35 takes HDMI or SDI video, encodes H.264, and sends the contribution feed over Ethernet. The usual internet workflow is simple: create an SRT listener in Callaba, then configure the NVS-35 as the SRT caller with the Callaba address, port, latency, and Stream ID when required.
Quick answer
To use Datavideo NVS-35 with SRT, set NVS-35 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.
The Datavideo NVS-35 sends one SRT contribution feed into Callaba. After ingest, Callaba can preview, record, route, restream, and feed multiview in parallel; these are downstream uses, not mandatory sequential setup steps.
- HDMI/SDI sourceCamera or switcher
- Datavideo NVS-35SRT caller, H.264 encoder
- Callaba GatewaySRT listener / receiver
- Preview
- Record
- Route
- Restream
- Multiview
What this setup does
This workflow uses the NVS-35 as a field encoder and Callaba as the public SRT gateway. It is useful when the venue network is ordinary internet access and the production team needs cloud-side confidence monitoring, recording, routing, multiview, playback, or restreaming without putting a production workstation at the venue.
The NVS-35 is specified by Datavideo as an H.264 dual streaming encoder with HDMI and SDI inputs, SD card recording, RTSP, RTMP/RTMPS Publish, TS, HLS, and SRT. For this guide, SRT caller from the venue to a Callaba SRT listener is the default because it avoids inbound connections to the venue network.
What this model can and cannot do in this workflow
- Confirmed: HDMI x1 and SDI x1 video input, with HDMI embedded audio, SDI embedded audio, RCA analog audio, XLR balanced analog audio, and mixed audio options.
- Confirmed: H.264/AVC High Profile Level 4.1 encoding and AAC-LC audio. Plan H.264 contribution, not HEVC/H.265.
- Confirmed: up to 1080p60 input formats are listed. This is not a 4K/UHD encoder workflow.
- Confirmed: SRT caller/listener fields are documented, including SRT Port, Caller IP Address, Latency, and Stream ID in caller mode.
- Important caveat: a generic direct-SRT passphrase field is not clearly listed in the direct caller/listener section. The SRTPassword wording appears in Datavideo’s DV Cloud path, so do not assume encrypted direct SRT unless your current firmware UI proves it.
- Not confirmed: NDI, ST 2110, and HEVC/H.265 for this exact model. Do not plan Datavideo NVS-35 as a native NDI source.
- Role clarification: the NVS-35 can be configured as an SRT caller or listener, but it is sold and specified as an encoder/recorder. It is not confirmed as a decoded HDMI/SDI return-feed device.
- Close product distinction: if you need a hardware SRT decoder with HDMI/SDI output, look at Datavideo’s NVD decoder family instead of treating the NVS-35 as a return decoder.
Recommended workflow
For an NVS-35 SRT to cloud workflow, I recommend keeping the NVS-35 behind the venue firewall and making it call out to Callaba. This is the practical answer to searches like NVS-35 SRT caller, NVS-35 SRT gateway, and Datavideo NVS-35 Callaba: the NVS-35 contributes the encoded feed, while Callaba receives, monitors, records, and routes it.
Use NVS-35 SRT listener only as an advanced fallback. Reversing the roles means the venue side must accept an inbound UDP connection, so you may need a public IP, UDP port forwarding, firewall rules, and a tested NAT plan.
When not to use this setup
- If the camera, switcher, recorder, and operator are all on the same LAN, a local SDI or HDMI path may be simpler than cloud ingest.
- If the only destination is a public platform and you do not need low-latency monitoring, routing, or cloud recording, the NVS-35 RTMP/RTMPS Publish mode may be enough.
- If the destination is a local RTSP player, the NVS-35 can serve RTSP, TS, or HLS locally; use a separate media server if multiple clients need to watch reliably.
- If the job needs native NDI, choose another device or an external bridge. NDI is not listed for this exact NVS-35 model.
Before you start
- Connect the program feed to HDMI or SDI and confirm the NVS-35 input source.
- Connect Ethernet and confirm the NVS-35 can reach the public internet.
- Use an uplink that leaves headroom above your video bitrate. For a first test, try about 4-6 Mb/s for 1080p30 or 6-8 Mb/s for 1080p60, then adjust to production needs.
- Confirm the current Datavideo manual and firmware on the event unit. Datavideo’s product page lists a newer E3 manual and firmware download area; the detailed UI labels often seen online are from E2 mirrors.
- If SRT handshake failures are difficult to diagnose, confirm compatible SRT major versions using Datavideo firmware notes or support information and Callaba server build or release information.
Create the Callaba ingest
In Callaba, create an SRT server/listener for the contribution feed. Choose a UDP port, decide whether a Stream ID is required, and keep the public hostname or IP address ready for the encoder. Open the chosen UDP port in the cloud firewall or security group.
Success looks like a listener waiting for an incoming caller. Before changing the encoder, confirm that Callaba is listening on the expected port and that no other SRT service is already using it.
Configure the NVS-35
Open the NVS-35 web interface and go to the stream operation page. Select SRT as the stream type, set the unit as Caller for the default cloud workflow, enter the Callaba public IP or DNS name as the Caller IP Address, enter the SRT Port, and set latency. The manual lists latency from 20 to 8000 ms with 1000 ms as the default; I would start at 1000 ms for a first internet test, then lower only after packet loss, RTT, and retransmits are stable.
If you use an NVS-35 SRT Stream ID, paste it exactly. Stream ID values are case-sensitive and whitespace-sensitive; a trailing space, copied newline, or changed capitalization can break the SRT handshake. Do the same check for any passphrase only if your current firmware exposes direct SRT encryption fields.
Settings table
| Where | What to do / field to fill | First-test value | Why / check |
|---|---|---|---|
| Callaba | Create SRT server and choose UDP port | Example: 9000 | Callaba must be listening before the NVS-35 starts. |
| Callaba | Stream ID requirement | Off for a simple test, or a known Stream ID | If enabled, the NVS-35 value must match exactly. |
| NVS-35 web UI | Operation Mode → Stream → Stream Type | SRT | Selects the SRT stream configuration path. |
| NVS-35 SRT settings | Stream Type | Caller | Best default for calling from a venue to cloud. |
| NVS-35 SRT settings | SRT Port | Callaba listener UDP port | Must match the Callaba SRT server port. |
| NVS-35 SRT settings | Caller IP Address | Callaba public IP or DNS name | Destination for the outbound SRT connection. |
| NVS-35 SRT settings | Latency | 1000 ms first test | Use the documented default first; tune later. |
| NVS-35 SRT caller settings | Stream ID | Exact Callaba value, if required | Case and whitespace must match. |
Monitoring
When the encoder starts, check Callaba for incoming bitrate, connection uptime, preview, audio meters, packet loss, RTT, and retransmits. On the NVS-35, refresh the web UI status page manually when needed; the manual notes that the web UI does not automatically update device status. A healthy first test shows stable bitrate, moving video, expected audio, and no repeated reconnects.
Recording and playback
The NVS-35 can record locally to SD card while also streaming, and Callaba can record the received cloud feed. Treat these as parallel recording choices. Local SD recording is useful as a venue backup; Callaba recording is useful when remote producers need immediate cloud-side files, playback, review, or downstream distribution.
Troubleshooting
| Symptom | Check in Callaba | Check on device | Likely fix |
|---|---|---|---|
| No connection | SRT server is running, correct UDP port is open, no caller connected. | NVS-35 is Caller, Caller IP Address and SRT Port are correct. | Fix IP/DNS, UDP firewall, port number, or role mismatch. |
| Handshake fails | Stream ID requirement and logs. | Stream ID text, including spaces and capitalization. | Re-paste Stream ID manually; remove copied newline or trailing space. |
| Connects, then drops | RTT, packet loss, retransmits, uptime. | Latency and uplink stability. | Raise latency, lower bitrate, or move to a better uplink. |
| Video but no audio | Audio meters and player audio track. | Selected audio source: embedded, RCA, XLR, or mix. | Select the correct input and confirm AAC-LC audio is present. |
| RTMPS fallback fails | RTMP/RTMPS ingest URL and stream key. | RTMP URL, Stream Name, Account and Password fields. | Test platform authentication and URL format before the event. |
| Version-related SRT issue | Callaba build or release information. | Datavideo firmware version and vendor support notes. | Confirm compatible SRT major versions or update firmware after testing. |
Official references
These are the most useful resources to keep next to the setup sheet.
Vendor references
- Datavideo NVS-35 product page
- Datavideo NVS-35 exported specifications
- Datavideo NVS-35 instruction manual mirror for UI labels — compare with the current manual from Datavideo before the event.
Protocol references
Callaba resources
FAQ
How do I use Datavideo NVS-35 with SRT?
Create an SRT listener in Callaba, then set the NVS-35 to SRT Caller and enter the Callaba address, UDP port, latency, and Stream ID if required.
Should the NVS-35 be SRT caller or SRT listener?
Use caller for the normal cloud workflow. Listener is possible in the documented SRT role model, but it usually requires inbound access to the venue network.
Is the NVS-35 an SRT receiver?
For this workflow, no. Treat it as the field encoder. Callaba is the SRT receiver/listener. Do not rely on the NVS-35 as a decoded HDMI/SDI return-feed receiver.
Does NVS-35 support SRT passphrase encryption?
Do not assume it for direct SRT. The generic direct SRT fields I would plan around are caller/listener, port, caller IP address, latency, and Stream ID. Confirm any direct passphrase field in your current firmware before the event.
Can I use NVS-35 as a native NDI source?
No. NDI is not listed for this exact model in the reviewed Datavideo specifications. Use SDI/HDMI locally or bridge with other hardware/software if an NDI workflow is required.
Can I use RTMP or RTMPS instead of SRT?
Yes. RTMP/RTMPS Publish is listed for the NVS-35. Use it when the destination is a platform ingest and SRT monitoring, routing, and recovery are not required.
Next steps
Build the workflow with a short private test first: start Callaba’s listener, start the NVS-35 stream, watch bitrate and audio meters, record a short clip, and verify that routing or restreaming works from the received source. Before the event, confirm firmware, SRT caller/listener direction, Stream ID, passphrase availability, latency, codec, and bitrate on the actual unit.
Try Callaba Gateway with Datavideo NVS-35 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.