Broadcast encoders (IP output)

How to set up a broadcast encoder or IRD with an IP output (Motorola / ARRIS, Harmonic, Ericsson, Cisco and others) to send MPEG-TS over UDP or RTP to Unda. Menu names differ from one make to another; the settings below are what Unda needs, whatever they are called on your unit.

Unda takes what these units send: H.264, MPEG-2 or HEVC video with AAC, MP2 or AC-3 audio, over UDP or RTP, as one channel or a multi-channel bundle (see What works with Unda).

Settings at a glance

Encoder setting	Set it to
Output interface	The IP / Gigabit Ethernet port, not ASI
Protocol	UDP, or RTP (then tick RTP on the Unda input)
TS packets per IP packet	7 (1316 bytes)
TS packet size	188 bytes (204 is refused)
FEC (SMPTE 2022-1 / Pro-MPEG)	Off: Unda does not use it on input
Destination	The Unda server's address and the input's port
Transport stream	SPTS (one channel); an MPTS bundle needs a Multi-channel input
Rate control	CBR, with null packets
PCR interval	40 ms or less
Scrambling (BISS, CA)	Off: Unda can't descramble
Video	H.264 Main or High
Frame rate	25 or 50 frames/s (in 50 Hz countries)
GOP / keyframe interval	1 to 2 seconds: 25 or 50 frames at 25 frames/s
Audio	AAC-LC, 48 kHz, stereo, 128 or 192 kb/s

Which input to add

Unda has two inputs for MPEG-TS over UDP and RTP. Which one depends on what the encoder sends:

The encoder sends	Add	Where
One channel, H.264 video and AAC audio (ADTS)	A UDP input (the lightest), or a Multi-channel input	Broadcast → UDP inputs
H.264 with MP2, AC-3, or AAC packed as LATM/LOAS	An MPTS input: it converts the audio to AAC	Broadcast → MPTS inputs
MPEG-2 or HEVC video	An MPTS input with transcode_video: true: it converts the video to H.264, about 1 to 2 CPU cores per HD channel	Broadcast → MPTS inputs
Several channels (an MPTS bundle)	An MPTS input	Broadcast → MPTS inputs

MP2 or HEVC on a plain UDP input

A plain UDP input takes H.264 with AAC only. A feed with MP2 sound goes live with no sound, and an HEVC feed gives no picture. Use a Multi-channel input for those, even when the feed carries one channel.

When in doubt, use a Multi-channel input. It lists what the feed carries (each channel's number, name and formats) before anything goes live, and inputs made in the dashboard are kept when the server restarts, as UDP inputs are. Both check the feed the way broadcast test equipment does (TR 101 290, including the PCR interval). Both are described in UDP / MPEG-TS and Multi-channel (MPTS).

Encoder settings

Network output

• Output interface: the IP or Gigabit Ethernet output. Unda has no ASI input; use an ASI-to-IP gateway for a unit without one.
• UDP or RTP: both work. With RTP, tick The sender wraps MPEG-TS in RTP on the UDP input (rtp: true in the configuration file), or use an rtp:// address on a Multi-channel input. RTP lets Unda put late packets back in order and count exactly how many were lost. The payload type must be 33 (MPEG-TS).
• 7 TS packets per IP packet, each 188 bytes. Unda accepts any whole number of 188-byte packets per datagram, but not 204-byte packets (with Reed-Solomon bytes): those are refused, and the server's log says the datagrams are "not whole MPEG-TS packets".
• FEC: Unda does not use SMPTE 2022-1 (Pro-MPEG) error correction on its inputs, so it does not help here. Leave it off rather than send traffic that is thrown away.
• Destination: the Unda server's address and the port you gave the input. Unicast (one server address) is the simplest. Multicast, on a local network, needs switches that support IGMP. The dashboard shows the input's port; the address is the server's own (on a cloud server, its public IP, the one your domain points to).

Transport stream

• SPTS (one channel) for a UDP input. An MPTS input takes one channel or a bundle.
• CBR with null packets. Unda accepts a variable rate too, but a constant one keeps the feed predictable. It matters most when the channel goes on to a TV bundle as it is: its rate must stay below its share there, or pictures reach TVs late (Unda raises an alert when that happens).
• PCR every 40 ms or less (DVB's limit). An MPTS input reports a longer interval as a TR 101 290 error, and so does a UDP input.
• No scrambling: BISS and conditional access must be off on the output sent to Unda.

Video

• H.264, Main or High profile, is passed through as it is, at almost no cost. MPEG-2 and HEVC are converted to H.264 by a Multi-channel input (see the table above).
• 25 or 50 frames per second in 50 Hz countries. A channel sent on to a DVB bundle as it is at 30 or 60 frames per second gets a warning.
• Keyframe every 1 to 2 seconds (GOP 25 or 50 at 25 frames/s; IBBP or IP are both fine). New viewers start at a keyframe, and HLS delay follows it: measured 6.8 s with a 2-second keyframe interval and 28.8 s with 8 seconds. Unda warns when keyframes are more than 4 seconds apart.
• Interlaced H.264 (1080i25) is passed through as it is, and a web browser may show it with combing on movement. For a stream watched online, prefer a progressive format (720p50 or 1080p25). Interlaced MPEG-2 converted by Unda is deinterlaced.
• B-frames are fine. Only low-latency WebRTC playback prefers a stream without them; the stream's Output tab warns when it has them.

Audio

• AAC-LC, 48 kHz, stereo, at 128 kb/s (a common rate for SD channels) or 192 kb/s.
• AAC can be packed two ways: ADTS works on both inputs; LATM/LOAS needs a Multi-channel input, which converts it.
• MP2 and AC-3 need a Multi-channel input, which converts them to AAC.
• 48 kHz is DVB's rate; a channel sent on to a DVB bundle with 44.1 kHz sound gets a warning.

Over the internet

UDP and RTP have no password and no encryption, and a lost packet is a visible glitch: nothing is resent. Use them on a network you trust: the studio LAN, a leased line or a VPN.

If the encoder must reach a server over the internet:

• Best: send SRT or RIST, which resend what the network loses. If the encoder speaks SRT, send to Unda's SRT port with the channel's key (SRT). If it doesn't, put a gateway next to the encoder that turns its UDP into SRT or RIST, and receive that with a Multi-channel input (srt://:9000?passphrase=… or rist://@:5000; see Over SRT or RIST).
• Unda does not speak Zixi's protocol. A Zixi gateway (or any other) must hand Unda UDP, RTP or SRT.
• Plain UDP or RTP anyway: give the input an allow list with the encoder's public address, open the port only to that address in the server's firewall (see the Firewall section of Install) and in your cloud provider's firewall, and expect occasional glitches from lost packets.

Checking that it arrived

Before the first broadcast, send a test feed and check it here:

• The channel appears under Streams with its picture size and frame rate. A UDP input's stream page shows its packet loss (the dot turns yellow at 0.1 % and red at 1 % over the last minute) and what was discarded: duplicates, malformed packets, senders not on the allow list, and a Transport stream line with its TR 101 290 check: click it for the full report.
• An MPTS input lists every channel of the feed with its formats on Broadcast → MPTS inputs, and each published channel's TR 101 290 errors. Click the feed's TR 101 290 label for the full report: which packets were lost, the PCR interval, and the tables the encoder sends.
• Nothing arrives? Check the server's firewall and the encoder's destination. Then check the packet size (188, not 204) and whether RTP is ticked on the input when the encoder sends RTP: both mismatches show as malformed datagrams.
• Picture but no sound on a UDP input: the encoder sends MP2, AC-3 or LATM audio. Use a Multi-channel input instead.