Portsdown vMIX

[G8KOE]

I have been trying to use the portsdown with vMIX with some success.
My system is an I7 PC with ffmpeg and vMIX installed and the Feb 2019 by Evariste F5OEO - QO-100 Release 0.9 batch file.
I have tried direct connection to portsdown and via my hub network with the same result.
Also tried lots of different settings but a typical setting would be SR333 FEC 3/5 pictures are very good but the sound keeps breaking up.
If I use DATV Express the sound and pictures are OK.
My programming knowledge is limited and I have come to a dead end.
Any help would be appreciated.

73’s
Martin
G8KOE

[g0mjw]

Hi Martin

The usual reason for sound break up is the video is taking too much bandwidth. Try reducing the resolution of the images.Also try 3/4 rather than 3/5 as I am not sure that's in the table of working settings.

With 333ks assuming you are not using H265 you should limit your resolution to 640x360 if there is a lot of image movement.

You can also try this in the script

set the PCRPTS to 1500

Where the bandwidth calculation is done there is a line that scales the video data rate, someting like 750 / 1000 - change that to 650 / 1000

Mike

[G8KOE]

Hi Mike,
Thanks for reply have been trying lots of different settings SR FEC 264 and 265.
264 is slightly better but still breaks up.
One of the tests is a static TC with music.
I will try your settings.
Thanks again
Martin
G8KOE

[g0mjw]

I should ask- is this break up just with you or with others too? I.e it's not an RX problem rather than a TX one. Checking in VLC sometimes helps as you can look at codec statistics.

[G8KOE]

Hi Mike,
With my limited understanding of the Feb 2019 by Evariste F5OEO - QO-100 Release 0.9 batch file not sure that I am modifying it correctly.
I will have another go later if can get the brain cell working.
BFN
Martin
G8KOE

[g0mjw]

Maybe - with Evariste's permission we can add some comments to the file so you know what's happening. I have my own version and have lost track of what was in the original.

[g3zgz]

I'm using the batch file Dave G8GKQ wrote reasonably successfully.

I'd like to get hold of the file you mention - Evariste F5OEO - QO-100 Release 0.9 batch file. Where can I find it, or could someone mail it to me please?

Can't help with the problem, other than saying when I use MiniT to decode my VMIX/Portsdown/Lime signal the sound occasionally breaks up.

When I UDP the MiniT to VLC the sound is good. I have heard this on other signals on QO-100, but can't offer any help other than saying VLC is better - possibly it's checks on the video and sound streams is slacker than MiniT's.

73
Dave.

[G8KOE]

Hi,
I have just started again with a new copy of Evariste F5OEO - QO-100 Release 0.9 batch file.
The results have been encouraging.
I may have change things in the batch file and not put back to original.
I will do more tests.

73's
Martin
G8KOE

[G8KOE]

Hi,
My good results have been short lived.
The portsdown seems to have a mind of it's own.
My sound still keeps breaking up.
I will keep looking for a solution.

73's
Martin
G8KOE

[G8GKQ]

I've been monitoring this discussion, but not contributing as Portsdown with vMix is not a "supported configuration" and there is only so much that I can do! However, here are some thoughts:

In testing the Portsdown, there are 3 potential problems that seem to cause the symptoms reported:

• Poor sound/video encoding. You can troubleshoot this by sending the TS directly to VLC and checking that the stream is good there.
• Incorrect video/audio elementary stream or transport stream bitrates and/or insufficient null packets. I use TSReader on the received UDP stream from MiniTioune to keep an eye on this, and aim for about 20% null packets.
• Buffering problems in dvb2iq and limesdr_send. These are the same problems that are responsible for the yellows and reds on the table here: viewtopic.php?f=103&t=6070#p19583. You can check whether the fault lies here by transmitting using an old-style filter-modulator board and seeing if the fault goes away.

I am working on a new Portsdown version that may overcome these problems, This uses custom firmware/gateware in the LimeSDR Mini and Evariste's limesdr_dvb module. I am building the new version based on Raspbian Buster, so it will require an SD Card rebuild to install. Maybe a new Year present to the Portsdown community.

Dave, G8GKQ