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par Michel Vonlanthen HB9AFO

Portsdown 2019




Portsdown 2019:


Feeding Video to Portsdown from vMix:




Jetson Nano


Jetson Nano:


Use of the NVIDIA Jetson Nano for DATV:


Caméra USB


C'est la PI Camera qui donne les meilleurs résultats car sa résolution est directement pilotée par le RPI. Si on veut utiliser une caméra USB externe, telle la Logitech C920 par exemple, il faut que cette dernière soit connectée seulement après que le RPI ait booté.

Protsdown from OBS from John G7JTT


Firstly I'm no expert with this but thought I'd share my success with getting OBS to talk the the Portsdown. I'd also like to thank everyone who has helped me along the way, especially Evariste F5OEO who spent a marathon evening with me helping to the early hours of the following morning getting the system working.

Screenshot 2019-05-22 07.33.05.png

Screen shot of my setup

Screenshot 2019-05-22 07.33.05.png (1.1 MiB) Viewed 1841 times

You will need to setup the Portsdown to talk to your PC via a network cable, WiFi wont work reliably. I also set the Portsdown up with a fixed IP of by adding the text ip= to the cmdline.txt file found in the root of your SD card. Once you have set the Portsdown up and can confirm the network is working, you need to set up OBS. What I have done is to create several profiles and named them to reflect the SR/FEC settings so for 250Ks @ 3/4 FEC I named it 250Ks@3/4FEC I then went on to create another 4 profiles for the most common combinations of SR/FEC I use. The following is a copy of my 250Ks@3/4FEC ini file.





FFMCustom=muxrate=372100 mpegts_original_network_id =1 mpegts_transport_stream_id=2 mpegts_service_id=1 mpegts_start_pid=300

mpegts_pmt_start_pid=4096 pcr_period=40
FFVCustom=preset=superfast x264-params=nal-hrd=cbr:force-cfr=1:vbv-bufsize=1000



With OBS running click on the profile tab and then rename the default profile to 250Ks@3/4FEC. Now click on the file tab and go to show the profile folder. Within that window you will see a file basic.ini, right click edit then you should be able to copy and paste the above text into this file. You can set the preview screens up to what ever takes your fancy but the FFRescaleRes should be appropriate for the SR in use so 768x576 or 352x288 are better suited to SR333/250 where as 1280x720 is better left to SR's of 500Ks and above. You can now duplicate this profile and rename them to suit your own choice of SR/FEC combination, I have 250Ks@3/4FEC, 333Ks@3/4FEC,500Ks@1/2FEC,500Ks@3/4FEC and 1Ms@1/2. For each profile you will need to change the muxrate and FFVBitrate (video bitrate) values for your given choice of SR/FEC. Use this site ... lator.html to work out your own choice of SR/FEC combinations. The Netto TS bitrate is what you need but in Kmps so multiply by 1000000 then enter this as your new muxrate, to work out the FFVBitrate multiply muxrate by 0.0006 and round up to just 3 digits. Once OBS is set up you can test it's all working with VLC set to receive an network

connection on udp:// and hitting the start recording button on OBS.

Next is the script that you need to run along side OBS to add user details, the following should be copied into batch file and run.

@echo off
rem edited By G7JTT May 2019
rem Feb 2019 by Evariste F5OEO - QO-100 Release 0.9 (Completely rewritten)
rem Started from original tool
rem Idea from Portsdown vmix ffmpeg script

rem ================= SETUP ONCE ===========

set callsign=YOURCALL
rem Set appropriately
rem set raspi_ip=
set raspi_ip=
set ip=%raspi_ip%:10000

rem ================= INTERACTIVE =======================
rem --- SR asked only once ----
set SR=250
echo ==== Enter SR 250@3/4,333@3/4,500@1/2,500HD,1000@1/2 =====
set /p SR="SymbolRate(Ks) (%SR%)"

IF "%SR%"=="250" (SET TSBITRATE=372100)
IF "%SR%"=="333" (SET TSBITRATE=495700)
IF "%SR%"=="500" (SET TSBITRATE=494900)
IF "%SR%"=="500HD" (SET TSBITRATE=661100)
IF "%SR%"=="1000" (SET TSBITRATE=989800)
IF "%TSBITRATE%"=="" (GOTO :promptme)
echo SR=%SR%
echo Muxrate=%TSBITRATE%
rem ======================== Launch ffmpeg OBS =========================

echo launch ffmpeg OBS
start "OBS to udp/ts" /high ^
C:\ffmpeg\bin\ffmpeg ^
-i udp:// -c:v copy -muxrate %TSBITRATE% -c:a copy ^
-f mpegts -mpegts_original_network_id 1 -mpegts_transport_stream_id 1 -mpegts_service_id 1 -mpegts_pmt_start_pid 4096 -streamid 0:256 -streamid 1:257 ^
-metadata service_provider="QO-100" -metadata service_name=%callsign% ^
-flush_packets 0 -f mpegts "udp://%ip%:10000?pkt_size=1316"

You need to setup your call sign and IP address of the Portsdown if you did not use, the options are self explanatory with the exception of

500HD this is just 500Ks @ 3/4FEC and I use this to send HD video from my Logitech C920 webcam.

So to work with the Portsdown you need to select IPTSin via the touch screen or via the console from an SSH connection. You must select the

same combination of SR/FEC as the script and the OBS profile. Both the script and OBS must be running then press start recording button in

OBS, wait a while untill the FFMpeg widow settles down then hit TX on the portsdown. The first few seconds of the video will be a little funky but

it will settle down and should work well for the length of the over. There are some sources/transitions within OBS that don't seem to work well

with my set up, but just play around and find what works best for you.

Hope this will help and that I've explained it in a way that makes sense?

All the Best John G7JTT