UDP, RTP, Pro-MPEG and TCP

The transports in this group deliver MPEG-TS over the network without retransmitting lost packets; Pro-MPEG adds forward error correction to the stream but uses no return channel. The field of application is described in Other inputs and outputs and Pro-MPEG / RTP+FEC (SMPTE 2022-1/2), the recommendations for receiving high-bitrate multicast in Recommendations for working with UDP multicast.

UDP

Receiving and sending MPEG-TS in UDP datagrams — unicast or multicast, including source-specific (SSM).

Input

Field	Purpose	Values
Address (multicast group)	The multicast group the input listens to. An empty field means unicast reception: the node accepts everything that arrives at the specified port. The value also decides how the port is occupied: on a group several streams may listen on the same address and port, while with unicast reception the port is occupied exclusively.	an address, empty by default
Port	The receiving port. A required field.	1–65534, 1234 in the creation form
Bind interface	The interface on which the input listens on the port and joins the multicast group. Chosen from the list of the node’s interfaces — each is offered both by name and by address; “Any (default)” leaves the choice to the system. If the named interface is not present on the node, the input does not fail but goes into the waiting-for-the-administrator state and picks the interface up when it appears.	any by default
SSM source address	The source address for source-specific multicast reception (SSM): the group is accepted only from this sender, and a second sender on the same group will not spoil the stream. For unicast reception the field has no effect.	an IPv4 address, empty by default
Socket buffer (bytes)	The requested size of the socket receive buffer — a remedy against losses on bitrate bursts. Zero means the system default value, which is also stated under the field itself. The size given is a request, not a result: on a running input the volume granted by the kernel is printed under the field, and if the request did not fit into the system ceiling, a warning appears next to it. The value is read once, when the stream window is opened, and after saving it disappears until the next opening (Recommendations for network tuning for multicast).	default 0
Multicast rejoin (s)	The period of rejoining the multicast group. It is needed where a switch or a router forgets the subscription over time and the traffic ceases without any error at all. Zero disables the repetition; with unicast reception the field has no effect. Values greater than 4294 seconds should not be set: the time count overflows and the rejoining starts to be performed continuously.	default 0

Output

Field	Purpose	Values
Address (destination)	The address of the recipient: a multicast group, a unicast address or a host name that will be resolved through DNS. A required field.	an address or a host name
Port	The recipient’s port. A required field.	1–65534, 1234 in the creation form
Multicast egress interface	The interface through which the node sends multicast datagrams; it is chosen from the same list as “Bind interface” on an input. On a node with several networks it is worth setting explicitly — otherwise the interface is chosen by the system from the routing table; the window does allow the output to be saved with an empty field. When sending unicast the field has no effect: the interface for it is always chosen by the routing table.	chosen by the system by default
IP multicast TTL	How many routers are entitled to pass the datagram on. The default value is meant for a local network; to deliver through routers it is increased, and to forbid leaving the segment it is set to one. When sending unicast the field has no effect.	1–255, default 4
Packets per datagram	How many TS packets the node puts into a single datagram. Seven packets are 1316 bytes, which fits into an Ethernet frame without fragmentation; a smaller value reduces the latency slightly at the cost of noticeably larger overhead. Changing it reopens the output — there will be a short break in the delivery.	1–7, default 7

RTP

The same UDP, but with an RTP header: the packets acquire a sequence number and a time stamp, so the receiver notices losses and reorderings.

Input

All the fields of a UDP input, plus:

Field	Purpose	Values
RTP reorder	Restore the packet order by the RTP numbers. It is enabled when the packets arrive out of order — for example, when the traffic is balanced over several paths. With the setting off the node does not look at the numbers at all: the packets go on in the order they arrived in.	disabled by default

The depth of the reordering queue is not configurable: the node chooses it itself from the stream bitrate.

Output

The fields of a UDP output without changes or additions: the RTP header the node forms itself.

Pro-MPEG

RTP with forward error correction according to SMPTE 2022-1/2: FEC packets are added to the stream, and from them the receiver restores losses without a return channel. By default the FEC occupies two additional ports — port+2 and port+4 — which is taken into account when planning (Pro-MPEG / RTP+FEC (SMPTE 2022-1/2)).

Input

All the fields of a UDP input, plus:

Field	Purpose	Values
ProMPEG multiplexing	A non-standard extension: the main stream and both FEC streams are sent over a single port, the additional ports are not occupied. The setting must match the sending side, and both sides must be Perfect Streamer nodes.	disabled by default
ProMPEG header XOR	Obfuscation of the FEC packet header: the header is XOR-ed with this number. A non-standard extension — the value must match on both sides, and for compatibility with third-party equipment it is left at zero.	0–255, default 0
Passphrase	The encryption passphrase — a non-standard extension (Stream encryption). An empty field means reception without encryption. A mismatch with the sending side is not recognized as an encryption error: the stream simply stops being parsed as MPEG-TS, and in the error message the node reminds you whether a passphrase is set on this side or not.	10–64 bytes or empty

A Pro-MPEG input has no separate reordering setting: the stream is always reassembled by the RTP numbers — without that the error correction would not work.

Output

All the fields of a UDP output, plus:

Field	Purpose	Values
ProMPEG columns	The width of the FEC matrix in packets. It sets both the cost of the row protection — one correction packet per that many transmitted — and the length of a consecutive loss that can still be restored.	4–64, default 8
ProMPEG rows	The height of the FEC matrix: one column correction packet per that many transmitted. The product “columns × rows” is the block size, and with it grows the restoration latency at the receiving end.	4–64, default 4
ProMPEG multiplexing	Sending the main stream and both FEC streams over a single port. The value must match the receiving side.	disabled by default
ProMPEG header XOR	Obfuscation of the FEC packet header; the value must match the receiving side. For compatibility with third-party equipment it is left at zero.	0–255, default 0
Passphrase	The encryption passphrase; it must be the same on both sides. What is encrypted is the contents of the packets, and the correction is computed on the already encrypted data.	10–64 bytes or empty

The node accepts a matrix that the standard does not require to be supported either: SMPTE 2022-1 limits it to a product of no more than 100 with 1–20 columns and 4–20 rows, whereas the fields allow up to 64 in each. Outside the standard, compatibility with a third-party receiver is not guaranteed.

TCP

Receiving MPEG-TS over an ordinary TCP connection — where UDP is blocked. The node always connects itself, so this type has no listening mode. There is no output of this type either: TCP delivery is performed by the streaming HTTP server (Streaming HTTP server).

Input

Field	Purpose	Values
Host	The source host the connection is made to: a name or an address. The window does not consider this field required, but without it the input will not work — an empty value will come to light only at start-up.	empty by default
Port	The port on the source host. A required field.	1–65534
Client timeout (s)	The time limit for establishing the connection and for a read already begun. The silence of an established connection is not limited by this setting: a source that has stopped is detected by the general stream timeout on the “Stream” tab (Configure stream), after which the stream switches to the backup input.	from 1, default 10

On losing synchronization at the TS packet boundary the input does not reconnect at once but tries to restore the alignment on the fly; a reconnection happens only when the alignment fails eight times in a row. The interface does not show a counter of such restorations.