Callaba
PricingSign inDeploy SRT gateway

Blackmagic Streaming Decoder SRT setup: receive SRT from Callaba and output SDI/HDMI

By Founder of CallabaUpdated
On this page

Step 1: create the Callaba SRT output

Create an SRT output or listener endpoint for the return feed. Keep the first test simple: port 5100, Stream ID return-feed, and passphrase empty unless encryption is required.

Do not skip the firewall step: if the decoder pulls from Callaba, open the Callaba UDP output/listener port. If Callaba pushes to the decoder, the decoder-side UDP port must be reachable.

Callaba SRT output for decoder Inline SVG reference for preparing an SRT output or listener route for the Blackmagic decoder. Callaba SRT output for decoder Inline SVG reference for preparing an SRT output or listener route for the Blackmagic decoder. Output name blackmagic-decoder-return Readable label for operators. Mode Listener/output endpoint Decoder pulls from this endpoint first. UDP port 5100 Open this port in cloud firewall. Stream ID return-feed Copy exactly to decoder source settings. Passphrase optional Same on both sides if encryption is used. Source Program / preview route Choose the feed that should appear on SDI/HDMI. Save
Inline SVG reference: create the Callaba SRT output first, then copy its values into the decoder source profile.

Step 2: configure Blackmagic Streaming Decoder

On the decoder side, create or edit the streaming source profile. Depending on software version and integration, this may be done in Blackmagic Streaming Setup, a custom XML profile, Ethernet Protocol, or REST API workflow.

Install steps 
First test source:
Protocol: SRT
Source / Server: YOUR_CALLABA_DOMAIN
Port: 5100
Stream ID: return-feed
Passphrase: empty or same as Callaba
Codec: H.264
Output: SDI / HDMI
Resolution: 1080p first if possible

Automation note: Blackmagic streaming products can also be configured through developer-facing Ethernet Protocol or REST API materials. This is useful for centralized setup, fleet control, or automated source switching.

For Blackmagic-specific configuration details, use the official Blackmagic Streaming developer documentation and the Streaming Decoder 4K technical specifications.

Blackmagic Streaming Decoder SRT source Inline SVG reference for decoder source fields: source URL, port, Stream ID, passphrase, codec and output. Blackmagic Streaming Decoder SRT source Inline SVG reference for decoder source fields: source URL, port, Stream ID, passphrase, codec and output. Protocol SRT Receive compressed stream from Callaba. Source YOUR_CALLABA_DOMAIN or IP Use DNS when field route can change. Port 5100 Must match Callaba output/listener port. Stream ID return-feed Treat as case-sensitive. Passphrase optional Same value if encryption is enabled. Output SDI / HDMI Map decoded video to physical outputs. Save
Inline SVG reference: source address, port, Stream ID, passphrase and output mapping are the fields to check first.

Settings table

Blackmagic Streaming Decoder SRT settings Indexable settings table for Blackmagic Streaming Decoder receiving SRT from Callaba: source URL, port, stream ID, passphrase, codec, output mapping, resolution, audio and firewall.Settings that must matchA connected SRT stream still needs decode, output and format checks.SettingCallabaBlackmagic DecoderWhyModeListener/outputCaller/pullconnectionSource URLpublic IP/DNSSRT sourcereachabilityPortopen UDP portsame portfirewallStream IDreturn-feedsame valueroutingPassphrasesame if usedsame if usedencryptionCodecH.264 firstH.264/H.265compatibilityOutputsource routeSDI / HDMImappingResolution/FPSHD firstmonitor standardhandshakeAudioAAC / embeddedSDI/HDMI outconfidenceFirewallinbound UDPoutbound UDPpath
SRT connection, decode compatibility and output mapping must all be correct.
Setting Callaba Blackmagic Decoder Why
Mode Listener / output Caller / pull Best first path behind NAT.
Port Open UDP port Same port SRT traffic must reach endpoint.
Stream ID return-feed same value Routes to correct feed.
Codec H.264 first H.264 / H.265 Best diagnostic path.
Resolution/FPS HD first (1080p) monitor standard should match Handshake with monitor
Output mapping source route SDI / HDMI Connection alone is not output.

Verify SDI / HDMI output

After the decoder connects, verify the physical output. A successful SRT connection does not guarantee that the monitor receives a signal.

Decoder SDI HDMI output check Inline SVG reference for confirming output mapping and signal standard after SRT decode. Decoder SDI HDMI output check Inline SVG reference for confirming output mapping and signal standard after SRT decode. Connection SRT connected Do not stop here; check decode and output. Codec H.264 first Use H.264 for diagnostics. Video standard 1080p / 2160p Match monitor and output path. Audio embedded Confirm audio on SDI/HDMI monitor. Output SDI + HDMI Map route to physical connectors. Reference optional Use facility sync if required. Save
Inline SVG reference: output mapping and video standard are the last mile of the decoder workflow.

Monitoring thresholds

Practical thresholds: in good conditions, RTT is often around 20–60 ms. If RTT is consistently above 150 ms or keeps growing, check the network. Packet loss above 1–2% usually means you should increase latency, lower bitrate, or improve the uplink.

Bitrate check: if the incoming SRT bitrate is much lower than the configured source bitrate, or if it jumps heavily, check the source uplink, network load and encoder settings. Unstable bitrate can cause stutter, artifacts or short dropouts on the decoder output.

Also confirm source bitrate in Callaba, audio presence, codec, resolution, Stream ID, passphrase state and SDI/HDMI output status.

Troubleshooting

Blackmagic Streaming Decoder SRT troubleshooting Indexable troubleshooting diagram for Blackmagic Streaming Decoder SRT problems: source status, source URL, stream ID, passphrase, codec, output mapping, SDI HDMI standard and audio.Debug Blackmagic Decoder SRT in this orderCheck source, SRT fields, decode compatibility and physical output mapping.1. SourceCallaba has video?2. URLhost / port3. Stream IDcopy exactly4. Securitypassphrase5. CodecH.264 first6. OutputSDI / HDMI map7. Audioembedded / monitor
Start with the source in Callaba, then check SRT fields, codec, output mapping and monitor compatibility.

SRT connects but no SDI or HDMI picture appears

  • Check that the source in Callaba actually has video.
  • Temporarily switch the source to H.264 HD and test again.
  • Confirm the decoder output is mapped to SDI or HDMI.
  • Check whether the monitor accepts the selected resolution and frame rate.
  • If there is still no picture, check that the output format is supported by the monitor or the next device in the chain: resolution, frame rate, interlaced/progressive format, PAL/NTSC-era formats, 1080i vs 1080p, and UHD/HD mode. For diagnostics, temporarily set a common format such as 1080p50 or 1080p60.

FAQ

How do I set up SRT on Blackmagic Streaming Decoder 4K?

Create an SRT output in Callaba, then enter the Callaba source address, UDP port, Stream ID and passphrase in the Blackmagic Streaming Decoder SRT source profile. Start with H.264 and map the decoded signal to SDI or HDMI.

Can Blackmagic Streaming Decoder receive SRT?

Yes. Blackmagic Streaming Decoder 4K is designed to receive compressed H.264 or H.265 streams and convert them back to SDI and HDMI video output. Use SRT when you need a controlled, low-latency return or contribution path.

Why does Blackmagic Streaming Decoder connect but show no SDI output?

A connected SRT session only proves transport. Check that the Callaba source has video, the codec is supported, the Stream ID and passphrase match, and the decoded feed is mapped to the correct SDI or HDMI output.

Does Blackmagic Streaming Decoder support H.265 over SRT?

Yes, Blackmagic Streaming Decoder 4K is built for H.264 and H.265 stream decode. For troubleshooting, use H.264 first, then test H.265 after the SRT path and SDI/HDMI output are stable.

Can Blackmagic Streaming Decoder receive SRT from Callaba?

Yes. Use Callaba as the controlled SRT source and configure Blackmagic Streaming Decoder 4K to receive the Callaba SRT output or route. For the first test, let the decoder pull from Callaba if the decoder site is behind NAT.

What does Blackmagic Streaming Decoder 4K do?

It receives compressed H.264 or H.265 streams and converts them back to SDI and HDMI video output for monitoring, return feed, confidence viewing or facility integration.

Should the decoder pull from Callaba or should Callaba push to the decoder?

For most first tests, let the decoder pull from Callaba. This keeps the public listener endpoint on Callaba. Use Callaba push only when the decoder has a reachable public UDP port or controlled firewall/NAT path.

What codec should I use first?

Use H.264 for the first test. After the route and output are stable, test H.265 if the source, decoder and downstream monitor path require it.

Can the decoder output to SDI and HDMI?

Yes. The practical value of the decoder is converting the compressed stream back to physical SDI or HDMI output. Confirm output mapping, resolution, frame rate and monitor compatibility.

Do I need to open UDP ports?

Yes. SRT uses UDP. If the decoder pulls from Callaba, the Callaba output/listener UDP port must be open. If Callaba pushes to the decoder, the decoder-side UDP port must be reachable.

What should I enter as Stream ID?

Use the Stream ID or route key expected by Callaba, for example return-feed. Copy it exactly and treat it as case-sensitive.

Why does SRT connect but there is no SDI or HDMI output?

Check source status in Callaba, then codec compatibility, output mapping, video standard, monitor compatibility, Stream ID and passphrase. A connected SRT session does not prove that the decoder is outputting video.

Can Callaba record the same feed that goes to the decoder?

Yes. Callaba can receive or route the feed, record it, show it in multiview and also send it to the decoder as a return or confidence feed.

Can I automate decoder configuration?

Blackmagic provides developer documentation for streaming products, including Ethernet Protocol and REST API materials. Use those docs when you need centralized or automated configuration.

What codecs can Blackmagic Streaming Decoder receive over SRT?

Keep the decoder input to H.264 or H.265. For first diagnostics, use H.264 HD before testing H.265 or UHD output.

Can Callaba push SRT to Blackmagic Streaming Decoder?

Yes, if the decoder can listen on a reachable UDP port. In that case Callaba acts as SRT caller and the decoder acts as listener.

Next steps

Last updated: May 21, 2026

Try Callaba Gateway with Blackmagic Streaming Decoder

Create a Callaba SRT output, send a return or confidence feed to Blackmagic Streaming Decoder, and monitor the path before outputting it over SDI or HDMI.

See SRT server setup Open multiview demo SRT servers API docs

Put the workflow to work

Run this workflow in Callaba

Deploy on AWS, then verify the same path with your own source and destination.

Deploy SRT gatewayReview the deployment guide

Related SRT gateway guides