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Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 11:56 am
by M0MBO
Hi,
I've been chasing this issue for a while without success, so hoped someone could point me in the right direction!
Portsdown4(P4) with source Pi Cam or Comp Video gives perfect TX via Pluto, with RX on Ryde and SDR Television/LibreSDR.
Source (H264) OBS/FreeStreamCoder to P4. M2>IPTS Monitor works fine. But TX works but then freezes after a couple of seconds.
Appreciate any suggestions.
73
Malc
M0MBO
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 12:22 pm
by G3GJA
Malc
Please supply more information.
Have you followed the instructions here:
https://wiki.batc.org.uk/OBS_-_Open_Broadcast_Studio?
if yes, then answer these queries:
- 1.What symbol rate have you set the P4 and FSC to?
2. What is the default resolution in OBS and FSC?
3. What are the specs of the PC including the graphics card if fitted?
4. What encoder option have you selected in FSC?
73
Clive
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 12:54 pm
by g0mjw
M0MBO wrote: ↑Sat Dec 06, 2025 11:56 am
Hi,
I've been chasing this issue for a while without success, so hoped someone could point me in the right direction!
Portsdown4(P4) with source Pi Cam or Comp Video gives perfect TX via Pluto, with RX on Ryde and SDR Television/LibreSDR.
Source (H264) OBS/FreeStreamCoder to P4. M2>IPTS Monitor works fine. But TX works but then freezes after a couple of seconds.
Appreciate any suggestions.
73
Malc
M0MBO
This is usually because you are sending too much data to pass through the channel you are sending. Do the maths and tell us the result.
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 1:17 pm
by M0MBO
Hi Clive and thanks for responding.
1.What symbol rate have you set the P4 and FSC to? 333ks
2. What is the default resolution in OBS and FSC? OBS = 1280X720, FSC tried 1280X720 & 960X540
3. What are the specs of the PC including the graphics card if fitted? Intel i5-4570 @3.2gHz, Intel HD Graphics 4600, 8gb RAM
4. What encoder option have you selected in FSC? = Intel
Malc
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 1:38 pm
by g0mjw
So 333ks but what FEC? - needs to be set correctly in both places.
If for example the SR is 333ks and the FEC 2/3 gives you a data rate of about 440kb/s. So that's what the encoder needs to send, ideally a little less. Then there is the H264. I would not exceed 720p and ideally only 15 frames per second. Ideally the audio should be 32k or similar.
Oh yes, and don't expect WiFi to work.
Mike
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 1:45 pm
by M0MBO
FEC is 2/3 in FSC and P4
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 1:48 pm
by g0mjw
M0MBO wrote: ↑Sat Dec 06, 2025 1:45 pm
FEC is 2/3 in FSC and P4
OK - lower the resolution and frame rate. That's a very old CPU incidentally, from 2013, so may struggle.
Re: Portsdown 4 - OBS source freezes
Posted: Sat Dec 06, 2025 2:52 pm
by G3GJA
As Mike says it will struggle.
The CPU is too old to have video encoding that will be of use to you and you don't have a graphics card as an alternative.
Your only option with that computer is to drop the frame rate to 15fps and set the resolution in OBS and FSC to no more than 960 x 540, possibly as low as 640 x 360. Your PC just doesn't have the power.
Clive