RPI4, HDHomerun, UK Freeview ...

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lynnux
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RPI4, HDHomerun, UK Freeview ...

Post by lynnux » Tue Sep 10, 2019 10:09 am

I'm in the UK and replacing an 8 channel, mythtv 27, Linux Mint16, Freeview SD only, PC based system.

The proposed system needs to be able to record 4 UK Freeview HD channels (minimum), use Raspberry Pi's, possibly an HDHomerun Quatro tuner and be able to ad-cut and display HD recordings on a 4K and an old but good "HD Ready" TV.

Here's a picture from my mind's eye:
RPI4 Mythtv.gif
RPI4 Mythtv.gif (37.33 KiB) Viewed 505 times
Can any kind soul answer any of these questions for me please?
1. With my old system I split 4 SD DVB-T streams into 8 channels (multi-rec). Can mythtv do the same with HDHR DVB-T2 streams?
2. The HDHR sits on an ethernet switch without access to the internet. I assume it doesn't need to "call home" if used with mythtv?
3. I've put in a usb pctv stick just for EIT schedules as I don't want to use xmltv. Is this stick necessary or can myth get its EIT from the HDHR streams?
4. I've separated the 4K TV's myth frontend from the backend. I have no feel for whether an RPi4 (4Gb) is up to the job of running both?
5. It would be nice (eventually) to watch HD live TV on the "HD Ready" TV. I'm not sure how that would work without bridging eth0 and wlan0 on the RPI4?
6. I used to get bad recordings in certain weather conditions with my old DVB-T usb sticks. The DVB-T2 tuners in the 4K TV never have such problems. Can I safely assume the HDHR has similarly capable tuners?
7. I haven't found any hard tech. info. on the HDHR; just marketing stuff really. Any links gratefully received.

Thanks for any pointers, thoughts, alternatives ...

MikeB2013
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Re: RPI4, HDHomerun, UK Freeview ...

Post by MikeB2013 » Thu Sep 12, 2019 10:38 am

Can't answer about HDHR, but I have a Raspberry Pi4 (4GB) as a combined frontend/backend system with network tuners see viewtopic.php?f=46&t=3232#p15870

This was into a 4K TV but with Pi4 limited to 1080p output using legacy graphics (/boot/config.txt having hdmi_group=1 hdmi_mode=31)

As far as ad-cut (commercial flagging ?) is concerned, this has always been problematic for me on UK Freeview. I have not spent anytime trying to get it to work, I just setup frontend to use forward and reverse skip buttons to go past the commercials.

On Pi running Buster (and Stretch) commercial flagging runs (cannot speak for accuracy) for HD (h264) but fails on SD with segmentation faults, this appears to be arm architecture related, I have raised a mythtv trac ticket on this see https://code.mythtv.org/trac/ticket/13476

It should be noted that the current mythfrontend has not been optimised in anyway for the Pi 4 or Pi3 with Raspbian Buster. So anything higher than 1080p is not really viable at present, but of course this is also the maximum on current UK Freeview.

As a final point my Pi4 (4GB) is running with active cooling .i.e. a fan.

Mike

lynnux
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Re: RPI4, HDHomerun, UK Freeview ...

Post by lynnux » Tue Sep 17, 2019 8:06 am

Hi Mike, many thanks for the excellent info. and many apologies for the delay in replying (no email notifications on this forum it seems).

> 7 simultanous HD recordings 4 recordings on 1 tuner, 3 recordings on the other tuner.
Wow! I had no idea that was possible. Was that just by setting 4 channels per multiplex in capture card setup?

>This was into a 4K TV but with Pi4 limited to 1080p output using legacy graphics (/boot/config.txt having hdmi_group=1 hdmi_mode=31)
Very interesting. My old PC frontend automatically runs the HDMI output at 1080p 60Hz. Any reason not to use hdmi_group=1 hdmi_mode=16 ?

>As far as ad-cut (commercial flagging ?) is concerned, this has always been problematic for me on UK Freeview. I have not spent anytime trying to get it to work, I just setup frontend to use forward and reverse skip buttons to go past the commercials.
I spent a bit of time getting ads to cut well using link deleted/wiki/Commercial_detection_with_silences. It was well worth it as it rarely gets things wrong with defaultish presets (see attachment) on the commercial UK channels I watch (Yesterday & Channel 4).

>On Pi running Buster (and Stretch) commercial flagging runs (cannot speak for accuracy) for HD (h264) but fails on SD with segmentation faults, this appears to be arm architecture related, I have raised a mythtv trac ticket on this see link deleted
That's saved me a lot of disappointment! Thanks. [strike]Does the failure happen with or without an mpeg2 license? I'm guessing you'd need it for SD even though the MPEG2 copyright has now lapsed in the UK.[/strike]

>It should be noted that the current mythfrontend has not been optimised in anyway for the Pi 4 or Pi3 with Raspbian Buster. So anything higher than 1080p is not really viable at present, but of course this is also the maximum on current UK Freeview.
1080p is good enough for me!

>As a final point my Pi4 (4GB) is running with active cooling .i.e. a fan.
Yes indeed. A test without any heatsink using my HD TV stick using VLC showed the CPU temp in the high 70s C very quickly. (I think the on-board regulator got even hotter.)

My hard disk and HDHomerun have just arrived. I shall be running them up soon with the help of your very useful scripts - BIG thanks for those Mike!

Bob
Attachments
silence.preset.txt
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Last edited by lynnux on Tue Sep 17, 2019 9:10 am, edited 1 time in total.

lynnux
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Re: RPI4, HDHomerun, UK Freeview ...

Post by lynnux » Tue Sep 17, 2019 9:07 am

@MikeB2013
Sorry Mike, Ignore my question re commflag and MPEG2 license - I just looked at your gdb log and can see it's clearly not that.
Bob

MikeB2013
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Re: RPI4, HDHomerun, UK Freeview ...

Post by MikeB2013 » Tue Sep 17, 2019 11:16 am

There is no mpeg2 license for Pi4, the processor cores are capable of decoding mpeg2 in software.

Later versions of mythtv (29,30 and on) have Max Recording (aka multirec) setting in mythtv-setup>Input Connections>Interactions between Inputs, the setting used to be in Capture Cards Recording options from memory. Default for Max Recordings is 1, I usually set to 5 or 10 depending on input type. My VBOX Network tuners can max out built-in cpu processing capacity at around 5 per tuner (I can set it higher but it can lead to bad recordings due to processor overload in the VBOX). For native tuners e.g. USB sticks, PCI-e tuner I usually set to 10, this potentially ignores other limitations such as disk i/o, network bandwidth. One of my VBOX units has 4 tuners, but only a 100Mbit/s network interface, so I limit Max Recordings to 5 per tuner (allowing 20 simultaneous recordings, which if it ever happened would likely saturate the network interface).

Based on past experience, I have just used 50Hz to match UK broadcast . If you see picture judder every few seconds at 60Hz try changing to 50Hz. My TVs are setup to "just scan" on the hdmi input.

Forum reply emails are off by default, you can subscribe on a per forum basis.

Mike

lynnux
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Re: RPI4, HDHomerun, UK Freeview ...

Post by lynnux » Wed Sep 18, 2019 7:56 am

Many thanks for those nuggets Mike.

Framerate: I shall experiment. My old system and TV exhibited motion tearing which I never entirely eliminated and put down to lack of kosher Nvidia drivers. The tearing just disappeared with the new TV - it seems to handle anything with consummate ease.

Forum subs: I just clicked the "Topic Tools" -> Subscribe topic . The notification shows in the User Control Panel but, so far , nothing in my inbox. Not a biggie though.

blm-ubunet
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Re: RPI4, HDHomerun, UK Freeview ...

Post by blm-ubunet » Sun Sep 22, 2019 9:41 pm

Off topic but you mentioned Nvidia & tearing & I assume VDPAU..

Video tearing with nvidia VDPAU is indicative of driver using Blitter instead of Overlay mode.
VDPAU (nvidia) only guarantees tearfree video if using Overlay.

Blitter results from using a composited desktop.. composite manager that does not understand "Un-Redirect Full Screen" or is broken (mate mutter etc).
Mate's Compton can work okay but it isn't pain free.
A lot of the desktop composite managers do not interoperate well with Nvidia in particular so that's why people recommend basic simple desktops like xfce for HTPC on linux.

You can turn on the HUD in nvidia-settings to reveal bits of that.

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