Exact-model runbook · compact H.264 contribution
AJA HELO Plus to Callaba: one clean SRT contribution
HELO Plus is at its best when the job stays small and explicit: accept a known SDI or HDMI program, encode H.264 with AAC audio, send one SRT session to Callaba, and make a separate HELO Plus-managed recording if the production needs a field copy. Prove those functions independently before turning on the second stream output.
The direct answer
Media direction: HELO Plus sends the program and Callaba receives it. SRT roles: HELO Plus is the Caller and Callaba is the Listener. Create and start the Callaba listener first. In the HELO Plus WebUI, open Stream 1 Output, choose SRT Caller, enter the Callaba destination, and match the Caller Stream ID and encryption settings required by the listener.
“Caller” describes the endpoint that opens the connection; it does not describe media direction. Here the HELO Plus happens to be both Caller and media sender.
The three markers represent source arrival, Stream 1 contribution, and HELO Plus-managed recording activity. They are conceptual status cues—not packet timing, buffering, or redundant paths. Motion is removed when reduced-motion is enabled.
HELO Plus is a two-output H.264 appliance, not a small BRIDGE LIVE
The names sit near each other in AJA’s streaming range, but their operating roles are different. Use the exact model on the chassis and set expectations from its current specification.
HELO Plus
A compact, stand-alone encoder and recorder with one 3G-SDI input, one HDMI input, two streaming destinations, and simultaneous recording. AJA specifies H.264 output up to 1080p60, AAC-LC audio, and 10/100/1000 Ethernet.
The two outputs are not always two independent encodes. AJA’s v2.1r3 manual says that when the input is above 720p and above 30 fps at Full frame rate, only Encoder 1 operates; output selections assigned to Encoder 2 are forced to Encoder 1 and the WebUI warns the operator. That ceiling belongs in the capacity plan.
BRIDGE LIVE family
A rack platform for bidirectional encode, decode and transcode work, with higher channel density and broader codec, transport and I/O choices. That is where AJA positions workflows involving HEVC, multi-channel SDI, NDI options or UHD-scale conversion.
Use the separate BRIDGE LIVE procedure when the job starts with a pipeline or transcoding requirement rather than a compact H.264 program encoder.
HELO Plus can build layouts from its inputs and add graphics, but this runbook assumes the program composition is already approved. It does not claim native HEVC, UHD/4K, NDI, SMPTE ST 2110, decode or general-purpose transcoding for HELO Plus. For a broader model decision, use the AJA SRT workflow hub.
Version the runbook before touching the output
As checked on July 31, 2026, AJA’s current public HELO Plus firmware is v2.1.5, announced March 17, 2026. The current manual is v2.1r3, released January 6, 2026. Firmware v2.1 added the Caller Stream ID field and selectable SRT Listener mode, so an older screenshot may not match the controls below.
Do not turn an event-day bring-up into an unplanned upgrade. Check AJA’s release notes, back up the working configuration, update in a maintenance window, and rehearse the exact build. If the installed WebUI labels differ from this page, use the AJA manual that matches that installed version.
Write down one connection contract
Keep a small worksheet beside both browser windows. It prevents the most common failure: changing two ends at once and losing track of which value is authoritative.
| Item | HELO Plus | Callaba |
|---|---|---|
| Media direction | Send Encoder 1 output | Receive one contribution |
| SRT role | Caller | Listener |
| Destination | Callaba host or IP and listener port | Reachable host or IP and selected UDP port |
| Identity | Caller Stream ID, when used | Matching approved publisher Stream ID or peer IP |
| Encryption | AES choice and passphrase, when enabled | Matching session policy and passphrase |
| Media | H.264 profile, raster, frame rate, bitrate and AAC audio | Expected input and downstream decode requirements |
| Evidence | Input lock and Streaming Output state | Session, bitrate/loss/RTT snapshot, and a configured media proof |
Leave sustainable uplink capacity above the complete video, audio and protocol load. HELO Plus lets each encoder run from 100 kbps to 20 Mbps, but that range is a product capability—not a recommendation. Choose a rate from the measured venue path and the downstream picture requirement. SRT can recover some packet loss; it cannot create bandwidth that the uplink does not have.
Prepare the Callaba Listener first
Create one SRT Server resource
Use Callaba’s SRT Server workflow as the receiving listener for this contribution. Record its publisher destination, including the reachable host and UDP listener port. This page stays at the field-contract level because dashboard navigation can change independently of the device firmware.
Approve the publisher identity
Callaba’s current product contract supports access by approved Stream IDs or peer IP addresses, and it also supports a deliberately open guest mode. For a managed HELO Plus feed, approve the expected Caller Stream ID or venue egress address. Keep guest publishing off unless an accountable security decision requires it.
Restrict and open the right UDP path
Permit the selected UDP port through the instance firewall, cloud security group and upstream network controls. Restrict it to known sources where the venue address is stable. Opening TCP on the same number does not open the SRT path.
Start the listener before the caller
Keep Callaba’s live state visible. The HELO Plus should call an already-running endpoint, which makes the first connection result meaningful.
Configure Stream 1 as the SRT Caller
The following labels are verified against AJA’s current v2.1r3 manual. They begin in an already reachable HELO Plus WebUI and intentionally avoid inventing a save button or submenu that the manual does not make part of the SRT field contract.
Prove the input before configuring transport
Choose the intended SDI or HDMI video source and the approved audio source. Confirm input lock, expected format and visible audio level at HELO Plus. AJA specifies progressive H.264 output up to 1080p60; if the source is interlaced, verify the resulting progressive output with the receiver rather than assuming the format is passed unchanged.
Set Encoder 1 for an interoperable first pass
Use H.264 with the raster, frame rate, profile and bitrate approved for the job. HELO Plus supports Baseline, Main and High profiles. Its standard audio path is 48 kHz, two-channel AAC-LC; the optional four-channel license adds a second stereo pair. Start with the channel layout the receiver actually expects.
Open the exact output page
HELO Plus WebUI → Stream 1 Output
Enable Stream 1, select the intended encoder source, and set Stream Type to SRT Caller. Do not select SRT Listener for this direct workflow.
Enter the Callaba destination
In SRT Destination URL, enter the Callaba publisher destination with its host or IP and the listener port supplied by Callaba. Preserve the actual endpoint rather than copying an example from another venue. If a hostname is used, verify DNS from the HELO Plus network before show time.
Match identity and encryption exactly
Set SET Caller Stream ID to the publisher identity approved in Callaba. If encryption is enabled, select the agreed value in SRT Caller Security—AJA lists AES-128 and AES-256—and enter the matching SRT Caller Encryption Passphrase. Treat the passphrase as a secret; do not paste it into screenshots, chat or the public runbook.
Start only the output you intend
Review whether Stream 2 is enabled, then start streaming with the WebUI Stream control or the front-panel Stream button. AJA documents both controls. Keep the HELO Plus status page and Callaba live view open while the session establishes.
Require three proofs before adding production outputs
1. Source proof
HELO Plus reports the intended SDI or HDMI format. The correct audio source moves its meters. Encoder 1 has the approved raster, frame rate, H.264 profile and bitrate.
2. Transport proof
The HELO Plus Streaming Output status and Callaba both show a sustained session. Callaba’s incoming bitrate is plausible, and live loss and RTT fit the production’s latency and uplink budget.
3. Configured media proof
Add one explicit confidence path from the received feed: a Multiview tile or a short Callaba recording. Confirm decode, clean motion, the intended stereo pair and sync; if recording, play the clip back.
An SRT connection state alone does not provide the media proof. Configure that one confidence branch for acceptance, then retain it or remove it before adding the production outputs. Callaba’s bitrate, loss and RTT are live operating context, not durable history, an end-to-end quality score, predictive diagnosis or automatic switching. Capture evidence in the production monitoring system if a post-event record is required.
- Test from the real venue uplink.
- Run long enough to catch periodic congestion.
- Listen; do not infer audio from video.
- Reboot and re-prove during rehearsal, not on air.
- Record the public egress IP and firewall rule.
- Keep the approved profile in the show file.
Give Stream 2 and Record separate jobs
Stream 2 is another output, not bonding
AJA lets HELO Plus send to two separate destinations and, within its processing limits, use different encoder parameters. That can support a second platform, a different rendition or a separately engineered backup destination. It does not make two sessions bonded, hitless or automatically selected by Callaba.
Check the source format before promising a second rendition. Under AJA’s documented v2.1r3 ceiling—input above 720p and above 30 fps at Full frame rate—only Encoder 1 operates and an Encoder 2 selection is forced to Encoder 1. If Stream 2 also goes to Callaba, give it a distinct approved identity and, when required, a distinct listener or port. Start it only after Stream 1 is stable and watch combined uplink load.
Record is a different proof
HELO Plus can manage recording to SD or USB media, or to a configured NFS or SMB target. An SD/USB field copy can survive loss of the contribution network; NFS/SMB has its own network and storage failure domain. None of these HELO Plus-managed recording paths proves that Callaba received the program. Conversely, a configured Callaba recording proves the received cloud-side program, not the health of device-side or network storage.
AJA’s v2.1.5 release notes warn against connecting recording media through a USB hub. Connect supported media directly and test the whole record/playback cycle before the event.
Troubleshoot the boundary that failed
No SRT session appears
Confirm HELO Plus is Caller and Callaba is Listener. Compare the actual host, UDP port and firewall rule. Check that the listener is running, the correct output is enabled and the venue can reach the destination.
“Network Name not found” appears
AJA lists a v2.1.5 known issue: this alarm can appear when the selected DNS service is unavailable even though streaming starts. Restore DNS, then verify the actual session at both ends. Do not treat either the alarm or the HELO status alone as proof.
The handshake fails with access enabled
Compare SET Caller Stream ID, AES selection and passphrase character for character with the Callaba policy. A reachable port does not mean the identity or encryption contract matches.
The session connects but picture does not
The transport boundary has passed. Return to the selected input and Encoder 1: verify input lock, H.264 output, raster and frame rate. In Callaba, distinguish an active SRT socket from a decodable media payload.
Picture arrives without the right audio
Check whether HELO Plus is using SDI embedded, HDMI embedded or analog audio, then verify the selected stereo pair and AAC settings. The optional four-channel license does not help if the wrong source pair enters the encoder.
The stream breaks up under motion
Compare the planned rate with sustained venue capacity and Callaba’s current loss and RTT. Reduce encoder bitrate or repair the path when the uplink is full. Do not repeatedly change identity, encryption and port while diagnosing a capacity fault.
HELO Plus recording works; Callaba is empty
The source and at least part of the encode/record path are alive. Focus on Stream 1 state, destination, DNS, UDP reachability and Callaba access policy. Keep the HELO Plus-managed recording as evidence, but do not call the contribution successful.
The appliance restarts or encryption state changes
Stop treating it as an ordinary media fault. Isolate the affected endpoint, preserve logs and follow your incident process and AJA-SA-2026-002. AJA specifically tells operators to monitor those symptoms while the security patch is pending.
Continue from one proven Callaba input
After the Stream 1 transport is stable and one configured confidence branch has proved the media, keep that ingest boundary unchanged. Retain the Multiview tile or recording if it belongs in production, then add the remaining downstream jobs one at a time. This is where Callaba becomes the gateway; HELO Plus remains the field encoder and recorder.
Watch it in Multiview
Put the received program beside other live sources for operator confidence. This is a configured downstream view that complements the device and transport checks.
Make a received recording
Record the signal that reached Callaba and play back a short proof. Keep it distinct from the HELO Plus field copy so each recording answers a different failure question.
Restream or provide playback
Build destination-specific outputs from the proven contribution. If one destination fails while Callaba ingest remains healthy, troubleshoot that branch instead of changing the HELO Plus.
Return to the AJA hub
Compare exact AJA workflows when the next source needs more channels, HEVC, decoding or transcoding. This page deliberately owns only the HELO Plus H.264 Caller procedure.
Operator questions
Can HELO Plus send SRT directly to Callaba?
Yes. Configure Stream 1 as SRT Caller and Callaba as Listener, then match the destination, publisher identity and encryption policy.
Should HELO Plus run as Listener instead?
Not for this direct recipe. Caller mode fits a field appliance making an outbound connection to a prepared cloud listener and avoids exposing an SRT listening port on the affected HELO Plus. It still does not remediate AJA-SA-2026-002.
Can HELO Plus send HEVC or 4K to Callaba?
Not according to AJA’s current HELO Plus specification. The appliance encodes H.264 up to 1080p60. Use a different encoder or the appropriate BRIDGE LIVE workflow when the job requires HEVC or UHD.
Does HELO Plus support two SRT destinations?
It has two configurable streaming outputs, and AJA lists SRT Caller and Listener support. Treat Stream 2 as a separate session with its own identity, destination, capacity and test—not as automatic bonding or hitless failover. At input formats above 720p and above 30 fps at Full frame rate, AJA says only Encoder 1 operates, so both outputs cannot be promised as independent renditions.
Is the HELO Plus-managed recording enough?
No. It proves a device-side file path. Configure a Callaba Multiview tile or received recording to prove what crossed the contribution boundary. For a critical production, test the relevant SD/USB or NFS/SMB recording path and a cloud-side confidence path.
Does firmware v2.1.5 fix the July 2026 SRT advisory?
AJA’s advisory does not say that. It says a HELO Plus patch using SRT library 1.5.6 or later is still in development at the July 31 check date. Follow the advisory for the current remediation state.
Official references used
AJA facts, interface labels, firmware state and the active security warning were checked against primary sources on July 31, 2026. Callaba boundaries were checked against the current SRT Server and operational product contracts.
- AJA HELO Plus product page and technical specifications
- AJA BRIDGE LIVE family product page
- AJA HELO Plus Manual v2.1r3 download page
- AJA HELO Plus Manual v2.1r3
- AJA HELO Plus Software v2.1.5 download page
- AJA HELO Plus v2.1.5 release notes
- AJA-SA-2026-002: SRT protocol library vulnerabilities
- AJA’s HELO Plus v2.1 feature announcement
Next step
Build one visible HELO Plus contribution
Prepare a restricted Callaba Listener, configure only Stream 1, and prove source, transport, decoded media and both recording boundaries. Add Stream 2 or onward destinations only after that baseline survives the real venue network.
