Cluster processing

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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KA5BBC
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Joined: Thu Jun 28, 2018 6:59 pm

Cluster processing

Post by KA5BBC » Thu Aug 13, 2020 11:17 am

I am asking for a friend, I know but this time I really am..

I have a friend who is starting to get into building a Portsdown and Langstone so that we can start demonstrations on-air. during one of our conversations yesterday he asked if I thought lose any benefit to running the RPis in a cluster to improve performance of encoding H264/265 etc. I have used parallel processing and render farms full video transcription and coding in the past but never for live streaming or transmission.. I have also never built a RPi cluster so I thought it most prudent to ask here.

Would it work and would it be worth it?
Andy, KA5BBC/MM0BQV

DL5BCA
Posts: 185
Joined: Tue Jun 30, 2020 11:59 am

Re: Cluster processing

Post by DL5BCA » Thu Aug 13, 2020 11:44 am

Wouldn't it be better to use a different platform, e.g. to use an ODROID-N2?

Is very similar to the Raspi, but much more powerful.

https://www.hardkernel.com/shop/odroid- ... yte-ram-2/
I always have crazy ideas.
Please don't be surprised.

G8GKQ
Site Admin
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Joined: Sun Mar 22, 2009 1:21 pm

Re: Cluster processing

Post by G8GKQ » Thu Aug 13, 2020 1:32 pm

Hi Andy

We use the graphics processor on the RPi for H264 encoding, and I am not aware of any cluster software for this. It was, after all, originally intended for use in mobile phones.

There could be potential in using multiple RPi main processors for H265 encoding but, like Thomas, I think that alternative hardware would be a better solution.

The NVIDIA Jetson Nano is similar the the Raspberry Pi (with even the same physical GPIO connector - although the electrical performance is not as good) and has excellent hardware H265 encoding capabilities. Cost is about 2.5 times the Raspberry Pi, and it can already be controlled by an existing Portsdown. I did write it up on the Wiki, but I am aware that my write-up needs updating as it does not work with the latest OS images supplied by NVIDIA.

Dave, G8GKQ

DL5BCA
Posts: 185
Joined: Tue Jun 30, 2020 11:59 am

Re: Cluster processing

Post by DL5BCA » Thu Aug 13, 2020 2:12 pm

I think the Jetson Nano is a good idea.
I had a DATV QSO with an OM via the QO100, which generated the H265 DATV signal with the Jetson.
It work very well.

It would be very interesting to consider doing the decoding directly in conjunction with Pluto or Lime
(this is a dream of the future)
I always have crazy ideas.
Please don't be surprised.

roland_F8CHK
Posts: 32
Joined: Fri Nov 17, 2017 3:05 pm

Re: Cluster processing

Post by roland_F8CHK » Thu Aug 13, 2020 3:54 pm

HI,

I think John G7JTT is doing that allready, transmitting and receiving simultaneously with a Jetson Nano and Portsdown combo! How he can do that is still a mystery for me!!

73,
Roland

DL5BCA
Posts: 185
Joined: Tue Jun 30, 2020 11:59 am

Re: Cluster processing

Post by DL5BCA » Fri Aug 14, 2020 6:35 am

Hi Roland,

I meant with the Pluto/Lime transmit and receive.
No MiniTiouner. Decode the received signal from the Pluto/Lime direct in Portsdown and display it on an external monitor.

I think you can do this on Windows with SDR Angle. SDR Angle is very cumbersome to use.

But this is a dream of the future.
I always have crazy ideas.
Please don't be surprised.

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