Digilite revival?

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mm0mgb
Posts: 41
Joined: Thu Oct 20, 2011 12:47 pm

Digilite revival?

Post by mm0mgb » Tue Oct 05, 2021 2:38 pm

Hi all,

I had an idea and maybe its daft but 'could I use OBS studio to generate the disk file for Digilite to transmit?' has anybody managed this and if so what settings did they find worked? I cab get it to recognise the file is there but it never actually starts streaming to to the digilite board. I Used the config program to set the Sr and FEC, the in OBS set the video data rate to the setting given but no bananas!

Any help appreciated and I know this is an old project from a good number of years ago but I just wondered if there was a way to get it going again. On my very old laptop with WINTV6 and with teh onboard SD card it all works fine, just looking at how to modernise via OBS.

Andrew MM0MGB

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: Digilite revival?

Post by G4EWJ » Tue Oct 05, 2021 4:18 pm

There's a blast from the past.

In theory, it should be possible. DigiLite v2.50 will do SR250, 333 and 500. You have to click OTHER and USER SR in the config program for 250 and 333. Also set INPUT METHOD to UDP-TS.

I don't know anything about OBS, but if it produces 188 byte transport stream packets, then DL should recognise it. DL will only do DVB-S, QPSK. The bit rate calculator was based on the PVR MPEG-2 capture cards, so OBS may need a bit of tweaking to get it exactly right. Is there any activity on the DL Transmit counters indicating reboots or resyncs?

Which SR are you using? DL was little used below SR1000, so it's possible that low data rates in UDP-TS mode may fall below some latency detection threshold in DL transmit.

Brian
Last edited by G4EWJ on Tue Oct 05, 2021 5:06 pm, edited 1 time in total.

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: Digilite revival?

Post by G4EWJ » Tue Oct 05, 2021 5:03 pm

I removed the incorrect bit rate formula from the previous message.

The input bit rate to DL of the 188 byte transport stream packets is:

SR * 2 * 188 / 204 * FEC - where FEC is a fraction like 3/4.

Brian

mm0mgb
Posts: 41
Joined: Thu Oct 20, 2011 12:47 pm

Re: Digilite revival?

Post by mm0mgb » Wed Oct 06, 2021 9:09 am

Hi Brian and thanks for getting back to me, I wasn’t trying the streaming solution but was trying to write the correct format of file to a disk as per the original wintv system, I have obs software with ffnpeg and am working on the basis there must be some combination that’ll work. I was also sticking with the original 2mbs as I built my digilite for 23cms. It sat for the last decade not doing a lot, although testament to the laptop that it originally worked with, still works, slowly!

I might give streaming a go and see if I can gate more success. The digilite TX program seems to see something valid as it stops saying looking for file but it never gets to displaying the counter stage, if I crack it I’ll put my settings here if anyone else is interested.

Andrew

G4EWJ
Posts: 1358
Joined: Wed Feb 17, 2010 10:11 am

Re: Digilite revival?

Post by G4EWJ » Wed Oct 06, 2021 2:43 pm

Sorry, I misunderstood how you were doing it.

DL Transmit expects the disk file to be in Program Stream (PS) format. This is what came out of the PVR capture cards. PS consists of two Packetised Elementary Streams (PES): one for video and one for audio. OBS/FFMPEG will have to create the two PES streams as an intermediate step before packetisation, so maybe it could write a PS to disk.

DL transmit will see the current disk file, but it won't be able to make sense of a 188 byte packet transport stream for the disk input method.

DL could, in theory, transmit DVB-S2 QPSK by modifying DL Transmit.

Brian

mm0mgb
Posts: 41
Joined: Thu Oct 20, 2011 12:47 pm

Re: Digilite revival?

Post by mm0mgb » Wed Oct 06, 2021 6:15 pm

Thanks Brian

My brain is hurting, I've been through the OBS FFmpeg options and I haven't found a format that can write the correct format to the disk, very frustrating as I'm sure it can be done but not by my brain! :lol:

Andrew

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