What is the best internal card I can get to use with MythTV

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oniscidea
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What is the best internal card I can get to use with MythTV

Post by oniscidea »

I have a Terratec Cinergy T PCIe Dual card. I've been using it with MythTV for the last 5 years.
At the beginning I had to download & compile drivers to get this card to work because it was not included in the kernel. Years ago the signal meter wasn't working well and I also had other problems like having to configure it manually. Later the Linux driver for that card evolved a little and was included in the kernel.
However all these years I had glitch/noise issues with that card. I don't know if it is the driver or maybe just MythTV application, but the fact is that I have tested several TV's connected to the same aerial and reception was always good, and not-so-good in my HTPC with this card. Audio and image glitches are frequent.
Now I am thinking of renovating my HTPC and getting a new DVB-T dual card. The question is: what would you recommend, based on your experience, having in mind that:
- It must have two DVB-T receivers (dual)
- It must be internal and for PCI express bus
- I will use it with mythbuntu
I'd really like to have a second receiver card to compare performance with my actual Terratec.
So... In your opinion: what is the best internal card I can get to use with MythTV?
Thanks community!!!
oniscidea
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Re: What is the best internal card I can get to use with Myt

Post by oniscidea »

No one uses an internal dual card working out of the box?

I had a look at http://parker1.co.uk/mythtv_novafw.php but don't know if it is actual info.

Good choice seems to be: TBS TBS6280 Dual Tuner DVB-T/DVB-T2 PCI-E: It says "The manufacturer officially supports Linux, although the driver is binary rather than open source. A highly recommended card."
But in https://linuxtv.org/wiki/index.php/TBS6280 I read "driver is NOT included in linux kernel, you must compile a closed (proprietary) or open source driver above to use your TBS6280 card"
Does anyone know if it is actualised info?
There is also a successor of TBS6280 called TBS6281but seems driver still not included in kernel...
MikeB2013
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Re: What is the best internal card I can get to use with Myt

Post by MikeB2013 »

I have used a TBS 6280 for some years with no problems.

I have used both the closed and open source drivers and would recommend the open source drivers as they use a much later version of the linux media stack. (V4L).

The open source drivers are at https://github.com/tbsdtv/linux_media/wiki

The downside of both drivers (closed and open) is having to rebuild them every time the linux kernel gets updated, not difficult, but you have to remember to do this.

One other point, if you have both a Terratec and a TBS card installed you will need to make sure the dvb adapter numbering is consistent across reboots (*buntu 16.04 and later uses systemd at startup with many things running in parallel which can cause adapter numbers to change - not good for mythbackend). There are a couple of solutions, one is to use udev rules, the other is to use adapter_nr (this is what i use as I also have a TBS 6981 dual DVB-S/S2 installed)

Mike
oniscidea
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Re: What is the best internal card I can get to use with Myt

Post by oniscidea »

Thanks Mike for the info... and for the clue regarding dvb adapter numbering!

So the TBS 6280 is a good option, but I need to compile the kernel on each update... OK!
You say that you are also using a TBS 6981, that I suppose is the successor of TBS 6980. Do you know if TBS 6281 (successor of TBS 6280) and TBS 6285 (successor of TBS 6284) are also good choices?

Apart from that, anyone knows of any dual PCIe card included in the actual kernel?
MikeB2013
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Re: What is the best internal card I can get to use with Myt

Post by MikeB2013 »

oniscidea wrote:Thanks Mike for the info... and for the clue regarding dvb adapter numbering!

So the TBS 6280 is a good option, but I need to compile the kernel on each update... OK!
You say that you are also using a TBS 6981, that I suppose is the successor of TBS 6980. Do you know if TBS 6281 (successor of TBS 6280) and TBS 6285 (successor of TBS 6284) are also good choices?
It is only the drivers you have to re-build (not the kernel) after each kernel update.
As far as I know any of the Dual or Quad TBS DVB-T/T2 PCI-e cards should be fine, as should the cards for DVB-S/S2.

TBS 6205 QUAD FREEVIEW DVB-T2/T/C Terrestrial / Cable Quad TV Tuner PCIe Card is a replacement for TBS 6285

TBS also have muti-standard cards, which I would avoid at this time. There are issues with mythtv/linux drivers which can be overcome but it can be messy. These cards have two frontends per tuner e.g. DVB-T/T2 and DVB-S/S2 but only one demux (so only one of the frontends on each tuner can be used at any one time), which is fine, but you may have to make adjustments to make sure the correct frontend is active. My understanding is that the linux core for DVB cannot automatically handle this situation at present, neither can mythtv.

Mike
oniscidea
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Re: What is the best internal card I can get to use with Myt

Post by oniscidea »

Thanks!
Just looking for a card supported by kernel, I also found that the DVBSky T982 card (Dual DVB-T2/T/C PCIe) seems to be a very good option. According to what people says it is supported by standard kernel drivers at least since 2015. Do you have any experience with T982 or other DVBSky cards?
oniscidea
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Re: What is the best internal card I can get to use with Myt

Post by oniscidea »

I decided to give a try to the DVBSky T982 PCIe dual tuner card, so from some weeks ago I am the owner of one of these cards.
I also made a fresh install of mythbuntu 16.04 with mythtv 0.28
The card worked out of the box EXCEPT for the fact that you have to put a firmware file (download it from the web: dvb-demod-si2168-b40-01.fw) in /lib/firmware. Once you put the file there linux does the rest.
The reception is good, but I still have glitches/artifacts that seem caused by bad reception. However my TV receiver does not show these defects, so I have the suspect that:
- Maybe tuner cards have les sensitivity than regular TV receivers (it seems strange to me)
- Or maybe mythtv software has some particularity that produces this phenomenon
I will keep investigating...
fe31nz
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Re: What is the best internal card I can get to use with Myt

Post by fe31nz »

Dual tuner cards need aerials just like single tuner cards. If the card has only one aerial input, but two tuners, the card likely has an internal splitter that takes that one input and passively splits the signal and sends it to each tuner. That means that each of the dual tuners will be getting only just less than half the signal level that you are providing at the aerial connection. If the incoming signal at the aerial connection is only just an OK level, after being split it may not be enough any more. So you are comparing a TV getting a full signal with tuners getting half that signal - not a fair comparision. If you put in another dual splitter between the TV and its aerial, then you can compare them.

As a result of this sort of problem, you may find it is better to use two single tuners rather than a dual tuner. That way, you can use a 3-way spliter with the TV and each tuner getting aroudn 1/3 of the signal level from the aerial, rather than the TV getting half and the dual tuners 1/4. Or you may need to amplify the aerial signal, then split it, and have an extra splitter in the TV connection to prevent it getting too large a signal level.

The other major cause of glitches on playback (where you get the same glitch each time, so it is clearly in the recording file), is when you are recording too many programs simultaneously to the same hard disk. When recording to multiple places on the same disk at once, the heads have to move back and forth all the time, and they are quite slow at doing that (compared to how fast a modern hard disk can write when the heads are on track). So they can take so long to move that mythbackend runs out of RAM buffer space and drops some data. This is a classic disk buffer overrun problem, and causes gaps in the data that is recorded to the recording files. Such gaps are pretty much the same as getting gaps or errored data from a tuner with reception problems - they are not easy to distinguish as they cause the same visible and audible glitches. And unfortunately mythbackend does not specifically log any buffer overrun errors that occur - you only find out about them by the glitches on playback or through roundabout means such as some of the extra logging done if you have "-v record" as an option on your mythbackend command line.

My rule of thumb is to never have more than two scheduled recordings happening on the same disk at the same time, except for overlaps due to pre-roll and post-roll. If I need to do more than that, I add a new hard disk. So now I have seven recording drives.
Cuppa-Chino
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Re: What is the best internal card I can get to use with Myt

Post by Cuppa-Chino »

oniscidea wrote:I decided to give a try to the DVBSky T982 PCIe dual tuner card, so from some weeks ago I am the owner of one of these cards.
I also made a fresh install of mythbuntu 16.04 with mythtv 0.28
The card worked out of the box EXCEPT for the fact that you have to put a firmware file (download it from the web: dvb-demod-si2168-b40-01.fw) in /lib/firmware. Once you put the file there linux does the rest.
The reception is good, but I still have glitches/artifacts that seem caused by bad reception. However my TV receiver does not show these defects, so I have the suspect that:
- Maybe tuner cards have les sensitivity than regular TV receivers (it seems strange to me)
- Or maybe mythtv software has some particularity that produces this phenomenon
I will keep investigating...
Hello I have one of those cards (actually a technotrend budget 4500 ci but I believe they are based on the same chips and (nearly) identical.

I can get the card to easily scan for both DVB T and DVB T2 channels in the UK using Kaffeine and all channels I was looking for are found really quickly and easily.

However in Mythtv I cannot get any locks on the card at all (using latest on ubuntu 17.04) - I think I can get channels to start if I have scanned them previously with an old DVB-T stick, but that of course cannot get me the HD DVB-T2 channels.

Any help ? Thanks
MikeB2013
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Re: What is the best internal card I can get to use with Myt

Post by MikeB2013 »

Cuppa-Chino wrote:
oniscidea wrote:I decided to give a try to the DVBSky T982 PCIe dual tuner card, so from some weeks ago I am the owner of one of these cards.
I also made a fresh install of mythbuntu 16.04 with mythtv 0.28
The card worked out of the box EXCEPT for the fact that you have to put a firmware file (download it from the web: dvb-demod-si2168-b40-01.fw) in /lib/firmware. Once you put the file there linux does the rest.
The reception is good, but I still have glitches/artifacts that seem caused by bad reception. However my TV receiver does not show these defects, so I have the suspect that:
- Maybe tuner cards have les sensitivity than regular TV receivers (it seems strange to me)
- Or maybe mythtv software has some particularity that produces this phenomenon
I will keep investigating...
Hello I have one of those cards (actually a technotrend budget 4500 ci but I believe they are based on the same chips and (nearly) identical.

I can get the card to easily scan for both DVB T and DVB T2 channels in the UK using Kaffeine and all channels I was looking for are found really quickly and easily.

However in Mythtv I cannot get any locks on the card at all (using latest on ubuntu 17.04) - I think I can get channels to start if I have scanned them previously with an old DVB-T stick, but that of course cannot get me the HD DVB-T2 channels.

Any help ? Thanks
There are a few things for you to try/check.
1. Make sure mythbackend is not running before you run mythtv-setup (sudo systemctl stop mythtv-backend.service). Strange things can happen if both are running.

2. Try changing the default timeouts for the Capture Card. I found the defaults of 1000 (Signal timeout) and 3000 (Tuning timeout) are generally too low for DVB-T/T2, but it does depend on your hardware configuration, software drivers, system load at time of tuning etc. I use 7000 (Signal timeout) and 10000. (Tuning timeout). Using these higher values does not affect normal operation (the timeouts are canceled as soon as tuning succeeds), but they do slow down channel scanning in mythtv-setup.

3. You do not state your mythtv version , but in Capture Card settings make sure "Open DVB Card on Demand" is not selected.

4. Unless you have enabled mythbuntu ppa for your version of mythtv it is not being kept up to date, to make sure it is updated (assuming your mythtv version is 0.28) do the following (see https://www.mythtv.org/wiki/Installing_MythTV_on_Ubuntu Install PPA for more information):
sudo add-apt-repository ppa:mythbuntu/0.28
sudo apt-get update
sudo apt-get upgrade

At this point I suggest you either reboot, or restart mythbackend (sudo systemctl restart mythtv-backend.service) - I usually reboot.

Note if upgrading from one mythtv version to the next version you should replace sudo apt-get update with sudo apt-get dist-upgrade


EDIT:
One thing I forgot:

Check the output of dmesg in a terminal session after you have run mythtv-setup channel scan, looking for messages indicating firmware download failed. I have seen situations where the firmware for a tuner needs to be installed in /lib/firmware.

Mike
Cuppa-Chino
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Re: What is the best internal card I can get to use with Myt

Post by Cuppa-Chino »

@Mike

thanks for the pointers - it actually turned out to be a problem with sneaky channel numbering...
my channel 12 from my satellite card was a channel "Astra SDT" - that seemed to tune very shortly and then actually froze the computer
When I deleted this "crashing channel" I was then able to get everything to work....

btw I am ubuntu 17.04 with mythtv 29
Jeffrey_Byrne
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Re: What is the best internal card I can get to use with MythTV

Post by Jeffrey_Byrne »

Nice, it's really knowledgeable thread.
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