What is SMPTE ST 2110? (vs NDI)

For decades, SDI (Serial Digital Interface) was the undisputed king of broadcast video routing. It was simple, reliable, and instantaneous. A 3G-SDI cable carried exactly one uncompressed 1080p video feed, embedded audio, and timecode on a unidirectional BNC copper cable.

But as resolutions scaled to 4K and 8K, and facility routing required massive, expensive hardware matrixes, the industry looked to IT infrastructure. Enter SMPTE ST 2110 (often just called "2110"), the open standard suite for Professional Media Over Managed IP Networks.

The Essence mechanism of 2110

Unlike SDI or NDI where video, audio, and data are multiplexed (bundled together) into a single stream, ST 2110 treats every element as a separate IP multicast stream. This is called the Essence model.

• ST 2110-20: Uncompressed active video.
• ST 2110-30: Uncompressed PCM audio (identical to AES67).
• ST 2110-40: Ancillary data (Timecode, Closed Captions, HDR signaling).
• ST 2059-2: PTP (Precision Time Protocol) clocking profile used to sync all of the above.

This means an audio console can subscribe only to the audio essence (2110-30) without having to ingest and demux a massive 12 Gbps 4K video stream just to extract the mic channels. It is incredibly efficient for facility-level routing.

SMPTE 2110 vs NDI

A common question is: "Why build a million-dollar 2110 network when I can just use NDI?" The answer comes down to compression, latency, and control.

The Control Layer: AMWA NMOS

While the ST 2110 suite handles how the video and audio packets travel, it doesn't specify how devices find each other. For that, the industry uses NMOS (Networked Media Open Specifications):

• IS-04 (Discovery & Registration): Allows a new camera to automatically appear in the facility's routing software as soon as it's plugged in.
• IS-05 (Connection Management): The protocol that actually tells a receiver "hey, start listening to this specific multicast IP from that sender."

The Importance of PTP (Precision Time Protocol)

If you break video and audio into separate network packets, how do you lip-sync them back together at the destination? PTP (IEEE 1588).

A Grandmaster Clock distributes an exact nanosecond-accurate timestamp across the entire network. Every ST 2110 sender stamps its packets with this time. The receiver looks at the timestamps and mathematically aligns the video packets with the audio packets, ensuring perfect Phase and Lip Sync. If your switch drops PTP packets or has bad QoS configs, the entire 2110 facility will collapse.