BATC Forum

Hi
I am trying to get going on QO-100 with DATV and I really could do with some help.
I am missing something that must be really obvious but I can’t see it.
My station setup so far
Portsdown 4 Latest version
Lime Mini firmware version 1.30
PA will do about 50 watts on DATV
1.2M offset dish with quad LNB
1.2M offset dish with potty patch deed and 4M of LDF405 feeder
RX MiniTiouner version 2. Ryde receiver or PC and software

I have successfully transmitted the portsdown test card and some analogue images from a video camera but the quality was not great.

I have seen some great pictures from stations using a portsdown setup.
I have been trying to improve my setup by using either VMMIX or OBS I have tried both and have followed the instructions in the BATC Wicki and I can send information to the Portsdown 4 using the IPSIN but the video is not great keeps stopping and the audio is stuttering.
I have tried a couple of different scripts without luck and played with settings.
Both the PC and Portsdown system are on a 1GB network all fire walls ect are off
If I monitor the VMIX/OBS output using VLC all seems fine the same if I use IPSmon on the portsdown 4 it’s when I try to TX it all goes wrong.
Dave G8GKQ has given me some advice around streaming settings bit rates ect but this is where I have run out of talent. There is something here that I don’t understand and need some help.
Can somebody try and point me in the right direction and if possible have a working script for either OBS or VMIX that they could share which might help me get this going.
I have put this project to one side for a few days as I don’t know what the next step is.

73 Keith GU6EFB

Hi Keith,

I expect your problem is you are not sending the transport stream at the correct rate. The correct rate depends on many things, symbol rate, forward error correction, modulation scheme, overheads etc etc. So, to start choose say 333ks and 2/3 coding H264 (BATC net). That should equate to a transport stream rate of 440 kb/s. The aim is to get OBS or VMIX to send this. A calculator is here: http://www.satbroadcasts.com/DVB-S_Bitr ... lator.html

Set your resolution to something sensible, not too ambitious to start with, say 640x360 or 768x432. If you can already get poor video this should be all you need. But there are lots of settings for ffmpeg that need to be optimised for best results.

Now you have some options. I wrote an article in CQTV about sending to a Pluto with some ffmpeg scripts. The same should apply with the Portsdown except you send it to the Portsdown rather than a Pluto. Alternatively you can try the settings to use OBS record to stream - the file basic.zip on the wiki should get you started. Not sure about VMIX as I don't use it.

The Wiki has an example basic file for OBS. https://wiki.batc.org.uk/OBS_-_Open_Broadcast_Studio

Here is my example using ffmpeg with the OBS Camera plugin.

c:\ffmpeg\bin\ffmpeg -f dshow -i video="OBS-Camera" -thread_queue_size 512 -f dshow -i audio="OBS-Audio" -vcodec h264 -s 768x432 -r 15 -bf 0 -pix_fmt yuv420p -b:v 300k -preset slow -profile:v main -rc cbr_hq -rc-lookahead 5 -acodec aac -aac_coder twoloop -ar 48000 -ac 1 -b:a 32k -f mpegts -muxrate 440k -streamid 0:256 -streamid 1:257 -max_delay 1500000 -metadata service_provider="G0MJW" -metadata service_name="Mike" -y "udp://192.168.1.46:8282?pkt_size=1316"


Hopefully that helps.

Mike

Hi Mike

Thanks for the help and advice.

Now understanding this all a little better and now have good video and audio from OBS into the portsdown. So one step closer to joining you all on the BATC Net.

Thanks again Mike

&3 Keith GU6EFB