Hi Guys,
Can you please do the dvbv5-scan again but then with the attached center frequencies file?
Code: Select all
dvbv5-scan -o result us-ATSC-8VSB-hutsmythtv-test
In this file I have removed the INVERSION lines that apparently caused the previous test to fail.
If this succeeds then the next step is to remove the INVERSION setting also from mythtv.
About your question
Is the demodulator setup error something in our Mythtv-setup config or something in the mythtv code?
This is something that the mythtv code does.
FYI, this is how it all works.
A capture card consists of a tuner and a demodulator.
The tuner tunes to a frequency and when it receives something it is in lock.
The output of a tuner is an analog signal. This analog signal then goes into the demodulator.
The demodulator is the part that convert the analog waveform into bits. The bits then go into the mythtv recordings.
The demodulator needs to know how to decode the analog signal and this has to be written into the demodulator by mythtv.
This are things as modulation system (e.g. 8VSB or QAM), symbol rate, inversion, forward error correcting code, guard interval and depending on the modulation system a few more.
If one of these settings is wrong then the demodulator will not produce bits and this is what can be the case with the WinTV card here.
Also interesting to know is that the demodulator is actually a small computer that requires its own software before it does anything. This is the firmware that is found in /lib/firmware and that is loaded into the capture card at boot (see the dmesg output). If loading the firmware fails then there is a message in dmesg.
If the firmware is not present then the demodulator does not work.
There can be also different versions of the firmware and one version might be better than the other.
It just could be that in your Ubuntu 20 the firmware is different from that in Ubuntu 18.
And then mythtv does not talk directly to the capture card; there is a driver in between. In Ubuntu 20 the driver will be newer than the driver in Ubuntu 18 so that difference can also be important.
That Kaffeine does work with your card on Ubuntu 20 means that the driver and the firmware do actually work. However, because MythTV does not work and because dvbv5-scan does not work with the standard ATSC frequency file it is certain that it has to be done differently from the way it used to be done. Figuring that out is what we are doing!
Thanks,
Klaas.