Linux scan options different from Windows scan options

[encore2097]

Hi, I was able to get channels on Win 10 install of NextPVR using the All countries / All frequencies QAM profile (first option).

This profile/option is not availabile in the linux install of NextPVR.

The profile I'm looking for seems to be listed in the /opt/nextpvr/system/data/tuning/QAM folder but they dont appear in the UI.

The only options that appear are the ones from /usr/share/dvb/atsc/

Copying the profiles from /opt/nextpvr/system/data/tuning/QAM/* to /usr/share/dvb/atsc/ and restarting nextpvr-server did not make them appear.

How can I use the same scan profile from Win in linux?

Thanks!

[sub]

NOn Linux it needs to use Linux-style tuning files. They’re supplied by the Linux TV development group (https://linuxtv.org). You can create your own file if you need to, by looking at the other existing files in that directory. You cannot copy in the windows tuning files - they don’t have the details and format Linux requires.

[mvallevand]

There is not one standard, you need to pick one from the appropriate cable choices in the atsc folder.

us-Cable-EIA-542-HRC-center-frequencies-QAM256
us-Cable-EIA-542-IRC-center_frequencies-QAM256
us-Cable-HRC-center-frequencies-QAM256
us-Cable-IRC-center-frequencies-QAM256
us-Cable-Standard-center-frequencies-QAM256

and yes they are slow to scan so be prepared/

Martin

[encore2097]

Thanks for the fast reply!

So I need to convert the qam.ini file into the linux format and place it in the appropriate directory?

edit: Isn't the scan the same in Win and Linux, NextPVR is asking the tuner to check a frequency. So there should be some code I can follow to see how the ini files are changed to scan parameters and then convert the to the linux format.

Or since I already scanned on Win 10, took about 20 min. Is there a way to copy my channel list from Win to linux and use that? Then I wont have to scan again.

[mvallevand]

You could create one, but my experience is clear QAM needs regular scanning when frequencies change. It is better to find out which master file your provider uses.

Martin

[sub]

Thanks for the fast reply!

So I need to convert the qam.ini file into the linux format and place it in the appropriate directory?

edit: Isn't the scan the same in Win and Linux, NextPVR is asking the tuner to check a frequency.

Unfortunately no, it doesn't work like that in Linux. It does in Windows. In Linux the TV tuner framework needs specifically format files, and it needs to read from them. (ie, NextPVR can't just pass in info from it's windows ini files)

Or since I already scanned on Win 10, took about 20 min.  Is there a way to copy my channel list from Win to linux and use that? Then I wont have to scan again.

Unfortunately no, the tuning info is different between the two platforms. (windows is more like the contents of the ini files with frequencies etc, and linux points at a tuning file and indexes entries by name)

[encore2097]

Thanks for the fast reply!

So I need to convert the qam.ini file into the linux format and place it in the appropriate directory?

edit: Isn't the scan the same in Win and Linux, NextPVR is asking the tuner to check a frequency.

Unfortunately no, it doesn't work like that in Linux. It does in Windows. In Linux the TV tuner framework needs specifically format files, and it needs to read from them. (ie, NextPVR can't just pass in info from it's windows ini files)

Or since I already scanned on Win 10, took about 20 min.  Is there a way to copy my channel list from Win to linux and use that? Then I wont have to scan again.

Unfortunately no, the tuning info is different between the two platforms. (windows is more like the contents of the ini files with frequencies etc, and linux points at a tuning file and indexes entries by name)

Doesn't make sense to me. Ultimately whats the flow look like?

I'd expect at a point in the flow there is a common format:

Win 10: NextPVR -> ini.file -> NextPVR -> Win DVB driver -> DVB card -> Scans frequencies

Linux: NextPVR -> linuxtv dvbfiles -> linuxtv -> linux DVB driver -> DVB card -> Scans frequencies

At the bare minimum the DVB drivers must send the same commands to the hardware to scan the frequencies, regardless of OS.

Simplified, a channel (perhaps the correct term is mux) is a frequency and encoding.

The ini files look like standard channels naming (1,2,3...) while the linux dvb files have frequency and additional parameters. I would expect, NextPVR or something else fills in the blanks to send to the driver.

But from what you're saying, it sounds like the inputs to the drivers are completely different. Am I understanding that correctly?

[mvallevand]

NextPVR doesn't directly communicate with the firmware. If you want a technical explanation you need to read up on Windows BDA and Linux libdvbv5 which provide the higher layer interfaces.

No one is asking you to use Linux if you prefer Windows use Windows. I honestly don't see why simply finding and using the appropriate linux file is that complicated. Start with STD then IRC then HRC (if you get channel 1 on the STB) and see how it goes.

Martin

[encore2097]

NextPVR doesn't directly communicate with the firmware.  If you want a technical explanation you need to read up on Windows BDA and Linux libdvbv5 which provide the higher layer interfaces.

No one is asking you to use Linux if you prefer Windows use Windows. I honestly don't see why simply finding and using the appropriate linux file is that complicated.  Start with STD then IRC then HRC (if you get channel 1 on the STB) and see how it goes.

Martin

I like to think I'm not a glutton for punishment

My linux server is running multiple services and I wanted to add NextPVR because I like the UI!

I had tvheadend working but it stopped so during my debugging I tested my dvb card on a different Win machine with NextPVR. It found channels!

On linux the same card shows no channels.

Scanning all 5 files will take hours so it makes it difficult to debug if my changes fixed whatever issue I'm having on linux. I have a previous VLC channel playlist from tvheadend but as you said QAM seems to change frequencies.

w_scan shows QAM signal OK but no data. The only thing that changed on my machine was a CPU upgrade and I reset the BIOS and changed some settings. I'm going to try to reset the BIOS and see if that fixes it but like I said waiting hours to see if it worked makes for a slow process. It would be nice if I could spot check a few channels or freqs that I found on Win!

thanks for sharing the dvb subsytem names for each os!

[mvallevand]

Here some punishment for homework then

If you have a tuning file that works on Windows for a specific channel go to this chart https://jneuhaus.com/fccindex/cablech.html then find the frequency multiple by 1000000 and and add 17500000 and us that to create a file in /usr/share/dvb/atsc with whatever name you want to give

Channel 2 = 55.25 translates to 57000000 as an example.

That page shows the math nicely for extra marks "The visual carrier frequency is shown in this chart. For the aural carrier frequency, add 4.5 MHz to the visual carrier. The lower edge of the channel is 1.25 MHz below the visual carrier and the upper edge is 4.75 MHz above the visual carrier. "

So the center frequency is halfway between (55.25 - 1. 25) and (55.25 +4.75) so halfway between 54 and 60 gives you 57 which turns in the 57000000 in the linux file.

Code:

# Sample for channel 2

[CHANNEL]
        DELIVERY_SYSTEM = DVBC/ANNEX_B
        FREQUENCY = 57000000
        MODULATION = QAM/256
        INVERSION = AUTO

If it works great if not you might to check your cable signal, update the linux firmware for the card etc.