OBS - Open Broadcast Studio

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Open Broadcast Studio is a free and open source software for video recording and live streaming.

It enables high performance real time video/audio capturing and mixing. Create scenes made up of multiple sources including window captures, images, text, browser windows, webcams, capture cards and more.

Screenshot 2019-05-22 07.33.05.png

Download

More details on the features and the program download from https://obsproject.com/

Using OBS with Portsdown

OBS can be used as a fully flexible video source for the Portsdown DATV system. The program interfaces in to the Portsdown over a wired network connection via an ffmpeg script developed by Evariste F5OEO.

Preparing the system

Software

As well as downloading OBS (making sure you get the right version for your system ie 64bit/32bit) and ensuring it runs on your PC, you will also need to download ffmpeg from https://ffmpeg.org/ - ffmpeg should then be installed on your PC at C:/ffmpeg. If you are using a Windows PC then you will need to change some files to ones compiled with pthreads as the w32thread compiled files will cause instability problems with your UDP stream. You can download the files from here Download. Once downloaded copy all the files in the ffmpeg-4.0.2-pthreads folder to C:/ffmpeg and over write the original files.

It is also useful to have VLC on the PC for testing, make sure you download the correct one for your system ie 64bit/32bit this will be important for later use with OBS - https://www.videolan.org/vlc/index.en-GB.html

Hardware

You will need to setup the Portsdown to talk to your PC via a network cable, WiFi wont work reliably. I set the Portsdown up with a fixed IP of 10.0.0.1 by adding the text ip=10.0.0.1 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.

OBS configuration

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 http://www.satbroadcasts.com/DVB-S_Bitrate_and_Bandwidth_Calculator.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://230.0.0.11:20000 and hitting the start recording button on OBS.

ffmpeg batch file

You now need to create an batch file to set the correct parameters in ffmpeg by cut and paste the text from this zip file:

File:ffmpeg OBS.7z