ST2110 and NMOS

Technical Overview

ST2110 and NMOS are a set of "standards" that try to give you real-time uncompressed video transmission over IP hardware. This is very different from video streaming in the following way:

• There is no buffering. ST2110 streams are transmitted line-by-line at microsecond precise intervals. While most devices will have a few frames of delay, this is nothing like traditional streaming does buffering
• Streams are synchronized to a PTP Grandmaster clock that works like Genlock in traditional SDI.
• There is no compression except optional 4:2:2 or 4:2:0 chroma sampling.

ST2110 defines how the pixels are transmitted over the IP network. It is based around the idea of transmitting video, audio and ancillary as independent "essences" so it is possible to process the smaller audio and ancillary streams without needing the fat video stream. This also means that we need 3 sets of configuration parameters.

Optionally, ST2110 allows to use "Seamless Protection Switching" (SPS via ST2022-7). As packet loss can be a problem with IP switched networks, all data is send to two independent networks with independent switching infrastructure, and all receivers will get IP packets from both networks, hoping that at least one actually arrives. Most high-end broadcast installations rely on this level of reliability, doubling the cost of the network infrastructure, and doubling the number of configuration parameters that need to be managed.

NMOS is a web-based system that allows to register, discover and switch ST2110 devices. This allows to create software where you can browse all registered ST2110 devices, get the network parameters of a sender and tell a receiver to listen to that sender. Most high-end broadcast installations will choose the NMOS information to go over a network that is separate from the "media network" that handles the high bandwidth video / audio / ancillary streams.

So in total we often have 3 networks in an ST2110 installation : two specialized high-bandwidth media networks for ST2110 and one control network for NMOS and other non-time-critical services like other web- and operating system services. With Ventuz one might add a cluster clock network and may be one needs networks for Dante audio.

As mentioned, we need a lot of configuration information to set up an ST2110 stream. This information is usually stored in SDP files, an old text-based format that contains IP addresses and video / audio parameters. Usually, an ST2110 stream has a video, an audio and an ancillary essence, each described in their own SDP file. If 2022-7 SPS is used, information about both networks are stored in the same SDP file.

In Ventuz, ST2110 can be used with or without NMOS. It is recommended to first try ST2110 without NMOS, and add NMOS installation later.

Configuring ST2110

In Ventuz, ST2110 streams are handled like SDI and other video devices. All we need to add is the network related information. This falls into two parts : the device settings and the per-stream settings.

Device configuration

For each device, we need to set the network interface settings:

• Eth0Ip, Eth1Ip : Ethernet interface IP
• Eth0Mask, Eth1Mask : Ethernet interface network mask
• Eth0Gateway, Eth1Gateway : Gateway
• Eth0Dns, Eth1Dns : (BMD only) Domain Name Server
• Eth1Enable : Enable second network interface
• EthDhcp : (BMD only) Enable DHCP (both interfaces if Eth1Enable)

You can read-back the actual internet settings in the live options with the EthConfigReadback property.

In addition to that, you can configure the PTP (precision time protocol)

• PtpDomain : Domain
• PtpPriority1 : Priority
• PtpPriority2 : Tie-breaker priority

On BMD only, you can check the chosen PTP Grandmaster in the live options with the PtpNegotiatedGrandmaster property.

Stream Configuration

For input and output streams, you can set a combined SDP file in the device config.

This file is created by concatenating the SDP files of the 3 essences together, in any order. You may add comment lines with '#' to make things more readable, but that is not required. This might look like this:

# video
v=0
o=- 21 21 IN IP4 192.168.200.200
t=0 0
m=video 10000 RTP/AVP 96
c=IN IP4 239.0.5.1/32
a=source-filter:incl IN IP4 239.0.5.1 192.168.200.200
a=rtpmap:96 raw/90000
a=fmtp:96 sampling=YCbCr-4:2:2; depth=10; width=1920; height=1080; exactframerate=60; colorimetry=BT709; PM=2110GPM; SSN=ST2110-20:2017; TP=2110TPN;
a=ts-refclk:ptp=IEEE1588-2008:00-00-00-00-00-00-00-00:127
a=mediaclk:direct=0
a=ssrc:0 cname:319b3fe6-0

# audio
v=0
o=- 31 31 IN IP4 192.168.200.200
t=0 0
m=audio 14000 RTP/AVP 97
c=IN IP4 239.0.5.1/32
a=source-filter:incl IN IP4 239.0.5.1 192.168.200.200
a=rtpmap:97 L24/48000/2
a=ptime:1
a=ts-refclk:ptp=IEEE1588-2008:00-00-00-00-00-00-00-00:127
a=mediaclk:direct=0
a=ssrc:0 cname:319b3fe6-0

# anc
v=0
o=- 41 41 IN IP4 192.168.200.200
t=0 0
m=data 18000 RTP/AVP 98
c=IN IP4 239.0.5.1/32
a=source-filter:incl IN IP4 239.0.5.1 192.168.200.200
a=rtpmap:98 smpte291/90000
a=fmtp:98
a=ts-refclk:ptp=IEEE1588-2008:00-00-00-00-00-00-00-00:127
a=mediaclk:direct=0
a=ssrc:0 cname:319b3fe6-0

This file is parsed by Ventuz by looking at lines that start with "v=", and that's where the 3 essences are split. The "m=" and "a=fmtp" lines are used to identify video, audio and ancillary.

Not all lines of these files are actually used:

• The video format and frame-rate of a sender are taken from the ventuz configuration. A receiver in "autodetect" mode will react to the format descriped in the SDP file.
• The devices interface parameters, as far as they are part of the SDP, are ignored. The device is configured through device options and can not be changed otherwise.

Parsing SDP files can be tricky, as this is not a modern file format. for Deltacast, Ventuz parses the SDP file and any problems with that can be fixed by us. For BMD, the Blackmagic driver parses the SDP file and any incompatibility can only be fixed by Black Magic.

A sender without any SDP file will automatically guess some reasonable defaults.

There are live options that relay the current configuration in the form of the combined SDP file of the 3 essences. These are created by putting together information found in the IP device options, traditional stream configuration and SDP file provided in the stream configuration. You can copy this from a Ventuz ST2110 sender and paste it in the device configuration of a Ventuz ST2110 receiver. You can also start a sender without SDP file, copy what Ventuz put together from the live options, change it to your liking and set as the final sender SDP in the device config. This is the simplest way to set up ST2110 senders and receivers without NMOS.

NMOS

NMOS is handled by software provided by the device manufacturer. This will override the stream configuration on the fly per NMOS commands. This is completely transparent and does not require additional configuration on the Ventuz side. The "SDP Readback" options represent the new settings as provided by NMOS.

Supported Hardware

Each vendor does different things on how configuration and NMOS are integrated:

How to set up IP Adress of the interfaces:

• BMD: Can be set up via control panel, can overridden by device config. We recomment using BMD control panel.
• Deltacast: Only via device config. Deltacast has no control panel.

Deltacast Considerations

The DELTA-ip-ST2110 board can be configured as input only or output only board via firmware update.

Deltacast has currently a few limitations. A firmware update expected late 2026 should allow us to solve these problems, but for now be aware:

• Video, Audio and Ancillary essences must share the same IP address, only the port may be different.
• When installing the NMOS service, video essences must be started via NMOS, or Ventuz will stall. Specifically, if more than one essence is configured, all essences must be running for Ventuz to render correctly.
• After deinstalling the NMOS service, you need to manually remove the registry key Computer\HKEY_LOCAL_MACHINE\SOFTWARE\DELTACAST\VideoMasterHD GlobalSharedMemory, or Ventuz will not find any Deltacast boards. Also, when the NMOS service is installed, it must be running, or you will not be able to use Deltacast boards
• Using multiple boards on the same computer with NMOS requires a specialized install procedure.