Portsdown repeater streaming

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Portsdown repeater streaming

Post by g8gtz » Tue Aug 01, 2017 9:15 pm

To all repeater keepers,

It is worth noting that the latest version of Portsdown software now enables the analogue audio and video input via the Eazycap dongle to be streamed out on the batc.tv streaming facility.

This means you no longer need a PC to provide 24 by 7 streaming for your repeater! Tim G4WIM has already tested this for the new GB3FT stream and confirms it works in console mode so no touch screen is required - just a Rpi and Easycap dongle....

73 Noel - G8GTZ

G4KLB
Posts: 251
Joined: Wed May 28, 2008 10:46 am

Re: Portsdown repeater streaming

Post by G4KLB » Thu Aug 03, 2017 8:35 am

I wish we could have our repeater on 24/7 :D
To save wasting bandwidth we only stream when the repeater is actually transmitting, it would be useful if the Rpi could be arranged to start and stop streaming from a receiver lock light signal.

G8GKQ
Site Admin
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Re: Portsdown repeater streaming

Post by G8GKQ » Thu Aug 03, 2017 3:24 pm

Hi Colin

I should be able to switch the stream on and off based on a logic level on one of the spare GPIO pins (the ones marked as DigiThin on the GPIO board). Is that what you're after?

I'll add it to the to-do list.....

Dave

g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Re: Portsdown repeater streaming

Post by g8gtz » Thu Aug 03, 2017 4:35 pm

Yes - I think that would be a very useful addition....

Noel

vk5bd
Posts: 35
Joined: Thu Dec 08, 2016 10:17 am

Re: Portsdown repeater streaming

Post by vk5bd » Fri Aug 04, 2017 4:06 am

Hello Colin,

Not fully understanding your repeater setup, does the lock light power your transmitter? If so could the same power switching, power the PIDATV BATC Streamer with automatic transmit setup on the Pi. I know it is not overly nice just powering down the Pi, but most of the time they survive. Maybe it is an option to get your stream on air until there are logic input functions added to the Portsdown code.

Regards,
Bevan

G4KLB
Posts: 251
Joined: Wed May 28, 2008 10:46 am

Re: Portsdown repeater streaming

Post by G4KLB » Fri Aug 04, 2017 10:27 am

Thanks for your reply Bevan,

Just to clarify our set up.

The streaming is done from a different site to the repeater as we don't have internet access there.
I have a receiver on all the time and when a valid lock is detected the streaming is automatically started on my PC (which has to be always on)
( see http://www.g8ajn.tv/ in the receiver section for details)

Using the Raspberry Pi will be a far more convenient solution.

73
Colin

G4WIM
Posts: 379
Joined: Thu Jan 29, 2015 8:36 pm

Re: Portsdown repeater streaming

Post by G4WIM » Sun Aug 06, 2017 7:39 am

Now I've had the Portsdown streaming for a few days I notice there can be 30 seconds to 1 minute of latency between local camera and viewing the stream.

As far as I can tell the bulk of the delay is in the Portsdown, but will do more checks.

Having this delay means that anyone using the BATC stream to check their input signal may think initially they are not accessing and so give up the attempt.

Not a big deal, but something to be aware of - I might put a message to alert others to this delay on the BATC stream.

73 Tim

g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Portsdown repeater streaming

Post by g0mjw » Sun Aug 06, 2017 9:32 am

Thanks for the report. Latency at low bit rates is too long with ffmpeg. Not sure if there is much that can be done about it.

No activity here on Winter Hill to test with but I did try GB3UD. I found I could not get into the repeater with the Portsdown, but I could with the DATV Express. Signals are marginal due to the patch antenna I was using, but it seems there are some problems. This was with the same antenna and amplifier so its probably the filtering being too tight. GB3UD uses an obscure 4167Ks/s which is likely to be at the limit.

Also found some strange behaviour after a while with the experimental distribution that meant MPEG-2 from the capture card was not streamed properly. I couldn't decode it locally either while H264 worked. This required a reboot and only worked sometimes, so not sure exactly what the issue is but timing is I think. I have since gone back to the non-beta software which seems stable at sending.

Mike

G8GKQ
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Re: Portsdown repeater streaming

Post by G8GKQ » Sun Aug 06, 2017 10:22 am

Mike - Please don't use the beta software - it's an old version at the moment. Please only report problems with the production build here. In the production software all streaming is H264 coded - it does not matter what you select.

4167 KS uses LC filters so should work fine. I can decode pictures at 6MS using the same filters. Could it be a PID issue? Was it H264 or MPEG-2?

Tim - I'm doing some more work on the streaming at the moment. I'll look into the latency issue, thanks for reporting it. You mentioned a camera; I take it that was a video input through the EasyCap?

Dave

g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Portsdown repeater streaming

Post by g0mjw » Sun Aug 06, 2017 10:57 am

Hi Dave,

This is why I went back to production, I had been testing the beta for you earlier and that's just how it was set up. I don't know what the problem was with GB3UD but it didn't work. I could it decode locally with minitioune, I wonder if it is related to the PIT which you state is not implemented yet? The GB3UD requirements are rather obscure, related to some older hardware but only MPEG-2 and PID has to be 32 with Video on 162 and Audio on 88. Portsdown sets the PID to the Video ID - or at least that's what it told me in the menu.

Yes, video input through EASYCAP. My PI camera has developed a fault, I think its the flat cable from the PI to the HDMI-style plug board which I may have damaged while making some modifications earlier on to allow more HDMI cables to work. Easy enough to replace.

While we are at it, Minitiouner Version 2 could not reliably decode GB3UD whereas a satellite receiver could. I put this down to the many strong signals up here overwhelming the wide coverage front end. A filter is needed, and is owned, but regrettably was left at home. To note for people trying to use the Minitiouner portable on hilltops on 23/13cms. You may find it works better with a band pass filter.

Mike

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