SRT How To - transmitting a RAVENNA stream over the internet

Owned by Nicolas Sturmel
Last updated: May 10, 2023

This how to will guide you trough the process a transmitting a stream over the internet, using Unicast Ravenna and SRT in Windows 10/11, you will need:

  • The srt-live-transmit application

  • the send and receive scripts

  • On site A, a PC with two NICs

    • NIC A-1 connected to the Ravenna Network, direct connection is possible

    • NIC A-2 connected to the internet, like a home or corporate network

  • On site B, a PC with two NICs

    • NIC B-1 connected to the Ravenna Network, direct connection is possible

    • NIC B-2 connected to the internet, like a home or corporate network

Download the binary and scripts there : https://drive.google.com/drive/u/1/folders/18qaWrxtTz-ABfSkPitQ4kq-qn41KHwPC

WARNING: The stream has to originate from a device that is NOT PC A and to be directed to a device that is NOT PC B

Schema of the system

 

 

  • Step 1 : creating the source for the unicast stream on a device

For this step you need the IP of A-1. Create a source on the device on site A and put the IP of A-1 in the Address field. If needed, add a port. Using a port different from the default one is useful when sending multiple streams. (default is 5004)

Exemple of address fields :

  • 168.254.7.120

  • 168.254.7.120:5006

Suggested ports value: 5006, 5008, 5010, 5012, 5014

Creating a unicast sender

 

  • Step 2 : modifying and running the send.bat script

@ECHO ON :: Please complete the variables set receiverPort=48009 set inPort=5006 TITLE Sending SRT ECHO starting srt-live-transmit srt-live-transmit udp://%inPort% srt://%receiverPort% pause

modify the values inPort and receiverPort:

  • inPort should be the same as the port entered before, if no port in the sink, default value is 5004

  • receiverPort is the port SRT will wit for a connection, it should be unique if you send multiple streams, let’s use 48009

Then go to the directory you downloaded the GoogleDoc files and run the modified send.bat:

You see the stats ? You should have them appear regularly, it means the stream is ready to be sent using SRT.

If stats do not show, try turning all settings OFF in your windows firewall.

  • Step 3 : open port-forwarding on your firewall

Now, let’s find the public IP of site A, browse to http://www.whatismyipaddress.com

Open the port on your router firewall on site B, for that, connect to your firewall and a “port forwarding”:

  • UDP port SRT port to IP A-2 from all sources

For instance → UDP port 48009 to 172.19.27.80 from all sources

BEWARE: Router firewall configuration is specific to your ISP

IP A-2 being the IP of PC-A on the home/corporate network.

  • Step 4 : modifying and running the receive.bat script

@ECHO ON :: Please complete the variables set senderIp=99.229.210.57:48009 set addressOut=192.168.0.2:5004 TITLE Receiving SRT ECHO starting srt-live-transmit srt-live-transmit -v srt://%senderIp% udp://%addressOut% pause

In this script:

  • Mark senderIP with the public IP of site A and the SRT port (receiverPort of script send.bat) with the scheme <IP>:<port>

  • Mark addressOut with the IP address of the receiving device (the IP of the Anubis, Hapi or whatever) and with a port. Again this port should be unique when receiving multiple streams

The script should tell you it can connect (SRT source connected)

Now you have to receive the stream on the device

  • Step 5 : creating the sink receive the unicast stream on the device

First create a sink, and tick the manual configuration to put your own SDP

v=0 o=- 1 0 IN IP4 192.168.0.1 s=Anubis_660217_1 t=0 0 a=clock-domain:PTPv2 0 a=mediaclk:direct=0 m=audio 5004 RTP/AVP 98 c=IN IP4 192.168.0.2/15 a=rtpmap:98 L24/44100/8 a=clock-domain:PTPv2 0 a=sync-time:0 a=framecount:48 a=palign:0 a=mediaclk:direct=0 a=recvonly

Replace the following lines:

  • line 2 from - 1 0 IN IP4 192.168.0.1 to - 1 0 IN IP4 <the IP of B-1>

  • line 8 from c=IN IP4 192.168.0.2/15 to c=IN IP4 <the IP of the receiving device on site B>/15

  • line 9 from a=rtpmap:98 L24/44100/8 yo a=rtpmap:98 L24/<sampling frequency>/<number of channels>

  • line 12 from a=framecount:48 to a=framecount:<framesize> with framsize the value from site A

Copy and paste the modified SDP and click apply.

You should be good.