Kiloview SRT User manual

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SRT User Manual
1. SRT introduction
SRT (Secure Reliable Transport) is an open source, free and flexible
application specification. It is a transmission technology that can
transmit data streams in a complex network environment in real time. It
uses the UDP protocol at the transport layer, although the UDP protocol
is an unreliable transmission protocol, with the powerful data recovery
capability of SRT, coupled with the fast speed and low overhead of the
UDP protocol, finally make SRT safe, stable and fast.
2. SRT application
2.1 Point-to-point one-way transmission and video interaction
During the transmission of audio and video streams from the SRT source
device (shown as below encoder) to the SRT target device (such as the
below decoder), the SRT will detect and adapt to the changing network
state between the two devices in real time, resist the bandwidth jitter
that caused by network congestion. With its powerful error recovery
mechanism, it can minimize the possibility of network packet loss. At the
same time, SRT can also perform AES encryption to ensure data security
during transmission.
SRT classic transmission way

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2.2 Point-to-multipoint transmission
The encoder supports adding multiple SRT points to push directly to
multiple target decoder addresses for point-to-multipoint transmission.
People can also use a streaming media gateway to distribute the video
stream sent by one encoder to multiple decoders. The streaming media
gateway is as the central node. The video stream sent by the encoder is
received first, and then copied and distributed to multiple decoders for
point-to-multipoint video transmission.
2.3 Video streaming protocol conversion and distribution
Media gateway devices (such as Kiloview D300plus/pro) can realize the
mutual conversion of various video streaming protocols such as SRT,
RTMP and RTSP. It copies, converts and distributes for each video stream,
which greatly increases the compatibility of SRT system. It also enables
various network flows such as local RTSP and RTMP to smoothly
integrate into SRT system, improving the flexibility of video forwarding.

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3. Encoder SRT function configuration
3.1 Click “Encoding & Stream”--“Encoding and Stream Settings”--“H.264
main stream”--“Add a stream”. Choose “SRT-TS pushing”, click “OK” and
add a SRT service.
3.2 Click the icon for SRT configuration.

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3.3 Fill in the pushing address and port, click “Save”. Then SRT pushing is
working.
Handshake mode: The device set as CALLER mode will act as the caller of
SRT session;
Address: Set IP address of the receiving port;
Port: Set the listening port corresponding to the receiving port;
Transport delay: Set it based on the performance of the current network,
the delay value can be set on both the SRT source device and the SRT
target device. The final SRT transmission delay will be the larger one of
the two values. Default is 125ms;
Advanced settings: Open and Close;

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Encryption mode: AES-128, AES-192, AES-256;
AES key: encryption AES key can be 10-32 letters or numbers
combination;
Bandwidth overhead: It is set as the percentage value based on network
link quality. Using this value to multiply the total bitrate of the audio and
video encoded by the encoder, this will get the occupied maximum
bandwidth allowed by Bandwidth Overhead. This value plus the total of
video and audio bitrate is the threshold of the current SRT transmission
bandwidth, and also the maximum bandwidth that SRT stream can be
used. From the perspective of "overhead", it is the extra "invalid"
bandwidth to be used in addition to the media content required for
transmission (which can be understood as the payload), but it is different
from our common protocol overhead, TCP header overhead, UDP header
overhead. The bandwidth overhead here is not a fixed 20~60 bytes TCP
header overhead or 8 bytes UDP header overhead. It changes in real
time according to the network conditions. The worse the network link
conditions are, the more overhead needs for normal transmission. The
range is 5%~100%, and the default overhead is 25%;
Load size: Sending data packet size, it is optimal that the receiving port
should equip with the same size. The default size is 1316, the optimal
packet for the codec.

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Note: Below format is the reference delay value under different packet
loss. When RTT＞20ms, it requires to increase the delay appropriately.
3.4 Save the settings, then a SRT-TS pushing address will be added. The
encoder starts to initiate a handshake connection to the receiving port.
Network highest
packet loss rate
(%)
RTT Multiplier BW Overhead The lowest SRT
delay (when RTT≤
20ms)
≤13 33 60
≤34 25 80
≤75 20 100
≤10 6 17 120

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4. Decoder SRT function configuration
4.1 Add a SRT source in the page of video decoder by “Media”--“Add
Source”--“SRT”.
Name: You can name it freely, supporting letters and numbers
combination;
Connection Mode: Listener;
Port: Configure a listening port which should be consistent with the
sending port;
Latency: please set it according to the configuration of the video encoder
and the final delay will be the larger one between encoder and decoder.
Default is 125ms;

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Encryption Mode/AES KEY: AES-128, AES-192 and AES-256. It should be
the same as the sender;
Bandwidth Overhead: Please set it according to encoder, the default one
is 25%;
Payload size: Please keep the same settings as the sender, the default
one is 1316.
4.2 Please add the SRT source to the output window, and the decoder
starts to listen for SRT requests, it will establish the SRT connection while
receiving the right SRT “Call”, and decode then output video.

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5. Media Gateway SRT protocol Conversion
Media Gateway (such as Kiloview D300Plus/Pro) can realize the video
stream protocols conversion between SRT, RTMP, RTSP and some other
protocols.
5.1 If RTSP/TS-UDP/RTMP/HLS/SRT to SRT, that is, the decoder works as
the “Caller” of SRT, and connect with other SRT receivers.
1) Add a stream service in the publishing points and choose SRT, click
“OK”.

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2) Enter the SRT configuration page, the SRT parameters can refer to that
of the encoder.
Notes: Delivery address format: srt://IP address: port
3) In “Choose a source”, you can choose the stream that you want to
convert from the source, then the stream can be converted to SRT
stream.

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5.2 If SRT to RTSP/RTMP, it will convert or distribute the SRT received in
local, and then convert it to RTSP or RTMP pushing.
1) In “Add Stream Services”, if adding type is RTMP or RTSP, it can convert
SRT to RTSP/RTMP.
2) In “Choose a source”, please choose the SRT stream that you want to
convert in the source, then it will be converted to RTSP/RTMP stream.

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Thank you for reading.
Changsha KILOVIEW Electronics CO.,LTD.
Phone：[phone]
Website：en.kiloview.com
Support email：[e-mail]
WhatsApp: [phone]
Skype: support_72698/keqiu wang
Address: 188#, Middle Huanbao Rd, Yuhua District, Changsha, Hunan Province, China