Short answer: an SDI IPTV encoder takes a professional SDI video feed — the BNC-connector standard used by broadcast cameras, switchers and production gear — compresses it to H.264 or HEVC, and sends it out over a network as an IP stream. You need one whenever your source is professional equipment rather than a consumer HDMI device: a stadium, a studio, a church, a lecture hall, a council chamber. The three things that decide which encoder to buy are the SDI variant your gear outputs (HD-SDI, 3G, 6G or 12G), the output protocol your destination expects (SRT, RTMP, RTSP or MPEG-TS), and how much latency you can tolerate.
At a glance
Choosing an SDI encoder
| Input | Match the SDI variant: HD-SDI, 3G, 6G, 12G |
| Codec | H.264 for compatibility, HEVC to halve bitrate |
| Protocol | SRT over the internet, MPEG-TS on a local network |
| Latency | Sub-second is achievable; know your budget |
| Redundancy | Dual power and dual outputs for live events |
Why SDI rather than HDMI
HDMI is a consumer standard. SDI (Serial Digital Interface) is what professional video runs on, and the differences matter in a live environment:
- Cable length. SDI over coax runs 100 metres and beyond without extenders. HDMI starts failing around 10–15 metres.
- Locking connectors. BNC twists and locks. HDMI falls out — and does so during the event, not during setup.
- Embedded audio and timecode. Multiple audio channels and metadata travel in the same cable.
- No HDCP. Professional sources don't carry the copy protection that blocks HDMI capture.
- Loop-through. Most SDI gear passes the signal on, so one feed can serve a monitor and an encoder.
If your source is a broadcast camera, a vision mixer, a converter or a rack-mounted player, it's almost certainly SDI, and an SDI encoder saves you a conversion step that adds failure points.
SDI variants and what they carry
| Standard | Data rate | Typically carries |
|---|---|---|
| SD-SDI | 270 Mbps | Standard definition, legacy gear |
| HD-SDI | 1.5 Gbps | 1080i / 720p |
| 3G-SDI | 3 Gbps | 1080p up to 60fps |
| 6G-SDI | 6 Gbps | 4K up to 30fps |
| 12G-SDI | 12 Gbps | 4K up to 60fps on one cable |
Buy for the signal you actually have. A 12G encoder is wasted money on a 1080p workflow, and a 3G encoder simply won't lock to a 4K60 feed.
What the encoder actually does
Four steps, in order:
- Capture. It locks to the incoming SDI signal and de-embeds the audio.
- Compress. Raw SDI is enormous — 3 Gbps for 1080p60. The encoder compresses it to something a network can carry, typically 5–20 Mbps, using H.264 or HEVC.
- Package. It wraps the compressed video and audio into a transport format the destination understands.
- Send. It pushes the stream out over Ethernet to a server, a CDN, a set-top box or a multicast group.
Everything you configure sits in step two and three: which codec, what bitrate, which protocol, how much latency.
Output protocols: SRT, RTMP, RTSP, MPEG-TS
SRT is the modern choice for sending video across the public internet. It recovers lost packets and tolerates unstable connections, which is why remote contributions and stadium feeds use it.
RTMP is what most streaming platforms still accept for ingest. It's old and has no error recovery, but it's universally supported.
RTSP suits local pull-based setups, where a server or player requests the stream from the encoder.
MPEG-TS over UDP, unicast or multicast, is the standard inside managed networks — hotels, hospitals, campuses, operator IPTV headends. Multicast is what lets one stream reach hundreds of screens without multiplying bandwidth.
Check what your destination requires before buying. An encoder that only does RTMP is useless feeding a multicast IPTV system, and vice versa.
Bitrate and quality settings
| Resolution | H.264 | HEVC |
|---|---|---|
| 720p50/60 | 3–5 Mbps | 2–3 Mbps |
| 1080p25/30 | 5–8 Mbps | 3–5 Mbps |
| 1080p50/60 | 8–12 Mbps | 5–7 Mbps |
| 4K30 | 20–25 Mbps | 10–15 Mbps |
| 4K60 | 35–45 Mbps | 18–25 Mbps |
Sport and fast motion need the upper end of each range; a static lectern shot needs the lower. HEVC roughly halves the bitrate for the same quality, but not every decoder supports it — check the receiving end first.
Also set the keyframe interval deliberately. Short intervals (1–2 seconds) let viewers join quickly and channel-change faster; long intervals save bandwidth. For live streaming, 2 seconds is a common compromise.
Latency
Encoding, packaging, network transit and the player's buffer all add delay. A well-configured SRT link can run under a second glass-to-glass; a standard HLS delivery chain runs 30–60 seconds behind.
Decide what you need before you configure anything. Lip-sync with an in-room PA, or a presenter interacting with remote viewers, demands low latency and a small buffer. A one-way broadcast benefits more from a larger buffer and fewer dropouts.
What to look for when buying
|
✓ Worth paying for The SDI variant your gear outputs SDI loop-through for local monitoring Multiple simultaneous outputs Dual power supplies for live events Web interface and API control Published firmware update history |
✗ Don't overspend on 12G inputs for a 1080p workflow 4K if nothing downstream handles it Protocols your destination can't accept Channel counts you'll never use |
For anything mission-critical, redundancy matters more than specifications: two power inlets, two network ports, and the ability to push the same feed to two destinations at once.
Common mistakes
Buying for the camera instead of the destination. The output protocol is what constrains you, not the input.
Ignoring upload bandwidth. A 12 Mbps stream needs sustained headroom above 12 Mbps, every second, for the whole event. Test at the venue, at the time of day you'll be live.
Using Wi-Fi. For a live encoder, wired Ethernet is not optional.
Setting the bitrate too high. A stream that exceeds the connection stutters. A lower, stable bitrate always looks better than a high one that can't be sustained.
Forgetting audio. Check which SDI audio pairs your source embeds on, and configure the encoder to take the right ones. Silent streams are almost always a de-embedding setting.
Frequently asked questions
What is an SDI IPTV encoder? A device that takes a professional SDI video feed, compresses it to H.264 or HEVC, and streams it over a network as IP video.
SDI or HDMI encoder? SDI if your source is professional gear — longer cable runs, locking connectors, no HDCP. HDMI for consumer sources.
What bitrate should I use for 1080p? Around 5–8 Mbps in H.264 at 25/30fps, or 8–12 Mbps at 50/60fps. HEVC needs roughly half.
Which protocol should I choose? SRT over the internet, RTMP if your platform requires it, MPEG-TS over UDP inside a managed network.
How low can latency go? Under a second over SRT with a small buffer. Standard HLS delivery is 30–60 seconds.
Do I need 4K? Only if the whole chain — camera, encoder, delivery and players — supports it. Otherwise 1080p at a solid bitrate looks better.
Bitrate figures are typical working ranges rather than specifications; check your encoder's documentation and test with your own content.