Portsdown repeater streaming

Discussion about this major DATV Project. See also https://wiki.batc.tv/The_Portsdown_Transmitter
G8GKQ
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Re: Portsdown repeater streaming

Postby G8GKQ » Sun Aug 06, 2017 12:02 pm

Hi Mike

The latest production software allows you to set the PMT, Video and Audio PIDs independently for MPEG-2. It is the PCR PID that is tied to the video PID. As I understand it, GB3UD needs the PMT PID set to 32 which is possible with the Portsdown. Grateful if you get a chance to test it.

Dave

ON1AVO
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Re: Portsdown repeater streaming

Postby ON1AVO » Sun Aug 06, 2017 5:19 pm

Why is the audio freq. range limited to +/- 6 kHz?
Tested with a stereo audiogenerator and UTV007 USB Videograbber.
Attached a screenshot of the VLC Codecinformation, Samplerate 11025 Hz instead of 48000.
Portsdown audio sample rate.jpg
Portsdown audio sample rate.jpg (59.68 KiB) Viewed 167 times

Freddy

G4WIM
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Location: Freckleton, Lancs

Re: Portsdown repeater streaming

Postby G4WIM » Sun Aug 06, 2017 6:54 pm

Hi Dave,

re latency - I was using the picam on my portsdown txing on 146.5MHz 333ksps into GB3FT but from looking at the local signal progress the delay seems to be in the streaming rx on 1315MHz which is a Comag SL30/12 into videocap dongle into RPI3 Portsdown code streaming to BATC.

So my bet is it's something to do with the videocap dongle /rpi streaming.

Quite amazed it has enough memory to buffer up so much video, but I do notice that sometimes just as it's about caught up it sometimes gets a bit confused and sends stuff out of order.

For instance if it is streaming the test card and I start to transmit, then after about 30 seconds it'll send a few frames of my transmission, then test card for a few seconds then finally my transmission.

This despite my transmission being solid as witnessed locally direct.

Hope all this makes sense and is of some use.

73 Tim

G8GKQ
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Re: Portsdown repeater streaming

Postby G8GKQ » Wed Aug 09, 2017 9:48 pm

I've been doing some work on how best to stream repeater outputs using the Portsdown. I've come to the conclusion that if people have a noisy signal to stream, then they are going to have to modify the Portsdown code themselves to suit their individual situation. This is easy to do.

I've started a Wiki Page here https://wiki.batc.tv/Repeater_Streaming and will update it with details of the hardware switching when that is released.

I have not yet managed to reproduce the long delays being reported. Next time someone sees it, please can they close their browser and restart it and see if the delay reduces. I think that some of the problem might be in the receiving browser, but am happy to be proved wrong - I just need to know!

Dave

G4WIM
Posts: 85
Joined: Thu Jan 29, 2015 8:36 pm
Location: Freckleton, Lancs

Re: Portsdown repeater streaming

Postby G4WIM » Fri Aug 11, 2017 6:51 pm

re streaming latency - I'll do my best to provide some hints as to where to look, including the BATC streaming web page because as a test I recently turned off my RPI streaming box but I continued to see video for about 20 seconds so I guess it could be the BATC box or even my local browser.

73 Tim


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