BATC Forum

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

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

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

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.

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

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.

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.

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

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

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