Cannot stream a 4K TV channel

eang

Hello,
I've been using Tvheadend for months on a RaspberryPi3 with its TV HAT. I'm located in Italy.
Everything has been working perfectly when streaming FullHD channels on the mpv client on my PC. The channels are encoded either with H264 and HEVC. So far so good.

Since a few week a new 4K channel has been introduced by Rai ("Rai 4K", on the 101 TV channel), however I'm not able to see it from mpv using the very same CLI that I've been using with every FullHD channel:

$ mpv "http://192.168.3.100:9981/stream/channelnumber/101"
Failed to open http://192.168.3.100:9981/stream/channelnumber/101.
[ytdl_hook] ERROR: [generic] Unable to download webpage: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response')) (caused by TransportError("('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))"))
[ytdl_hook] youtube-dl failed: unexpected error occurred

This is what I see from journalctl on the raspberry:

Feb 24 20:28:46 rpi3 tvheadend[594]: subscription: 006E: No input source available for subscription "HTTP" to channel "Rai 4K"
Feb 24 20:28:46 rpi3 tvheadend[594]: webui: Couldn't start streaming /stream/channelnumber/101, No assigned adapters
Feb 24 20:28:46 rpi3 tvheadend[594]: subscription: 006E: "HTTP" unsubscribing from "Rai 4K", hostname="192.168.1.150", client="libmpv"
Feb 24 20:28:49 rpi3 tvheadend[594]: subscription: 006F: No input source available for subscription "HTTP" to channel "Rai 4K"
Feb 24 20:28:49 rpi3 tvheadend[594]: webui: Couldn't start streaming /stream/channelnumber/101, No assigned adapters
Feb 24 20:28:49 rpi3 tvheadend[594]: subscription: 006F: "HTTP" unsubscribing from "Rai 4K", hostname="192.168.1.150", client="Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.3>

This channel should be HEVC encoded, I think. As already mentioned, I'm able to stream HEVC 1080p channels.

So my question is: is TVheadend supposed to work with a 4K channel? Does the raspberry TV HAT support 4K?

I'm happy to provide more info, just let me know what you need!

Thanks

chewitt

Tvheadend supports 4K channels, but AFAIK the Raspberry Pi TV hat only supports SD/HD not 4K.

eang

chewitt I've been investigating this, since I could not find this detail in the TV HAT official specifications nor anywhere else in the Internet. So I asked directly the Raspberry foundation: it took a while, but eventually one of their engineers did reply! This is what they told me:

The TV HAT supports DVB-T2, so whatever is transmitted on the mux, whether SD or 4K, should be received OK. I would expect the resulting stream to be HEVC, so make sure you decoder can support that format. The HAT connects to the PI via SPI, which should be capable of about 50MBits/s, which is more than enough for a 4k channel

The 4K channel I was testing has a bitrate of less than 20Mbps, so that shouldn't be a problem either.

Could this mean that something is actually missing in the tvheadend side, after all? Is there any way I could enable more logs to better see what's going on under the hood?

Thanks for replying, btw!

chewitt

I'm regularly watching F1 and other sports channels in 4K, although the server isn't using RPi hardware.

NB: Although I'm involved with the running of the project, I have rather limited Tvheadend knowledge so others will need to chime in with diagnostics. I guess debug logs wouldn't hurt though.

eang

dmesg shows the following after tvheadend fails to stream the 4K channel:

[Thu Mar 26 19:37:41 2026] cxd2880 spi0.0: DVB: adapter 0 frontend 0 frequency 0 out of range (174000000..862000000)
[Thu Mar 26 19:38:09 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:658000000 bw:8
[Thu Mar 26 19:38:10 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:38:59 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:498000000 bw:8
[Thu Mar 26 19:39:00 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:39:32 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:546000000 bw:8
[Thu Mar 26 19:39:33 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:40:09 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:610000000 bw:8
[Thu Mar 26 19:40:10 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:41:32 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:682000000 bw:8
[Thu Mar 26 19:41:33 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:42:49 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:594000000 bw:8
[Thu Mar 26 19:42:50 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:43:18 2026] cxd2880: cxd2880_set_frontend: sys:16 freq:626000000 bw:8
[Thu Mar 26 19:43:19 2026] cxd2880: cxd2880_set_frontend: tune result 0
[Thu Mar 26 19:44:03 2026] cxd2880: cxd2880_set_frontend: sys:3 freq:634000000 bw:8
[Thu Mar 26 19:44:04 2026] cxd2880: cxd2880_set_frontend: tune result 0

It seems tvheadend provides a --trace CLI option that should provide the most verbose logs. I'll try to use that and see if something interesting shows up with that.

eang

This is all I could get after enabling traces logs:

Mar 27 22:35:45 rpi3 tvheadend[596]: subscription: 00CC: creating subscription for Rai 4K weight 0 using profile pass
Mar 27 22:35:45 rpi3 tvheadend[596]: subscription: 00CC: find service for Rai 4K weight 100
Mar 27 22:35:45 rpi3 tvheadend[596]: subscription: 00CC: instance not available, retrying
Mar 27 22:35:47 rpi3 tvheadend[596]: subscription: 00CC: find service for Rai 4K weight 100
Mar 27 22:35:47 rpi3 tvheadend[596]: subscription: 00CC: No input source available for subscription "HTTP" to channel "Rai 4K"
Mar 27 22:35:47 rpi3 tvheadend[596]: webui: Couldn't start streaming /stream/channelnumber/101, No assigned adapters

Not much, unfortunately 🙁

DeltaMikeCharlie

eang
Mar 27 22:35:47 rpi3 tvheadend[596]: subscription: 00CC: No input source available for subscription "HTTP" to channel "Rai 4K"
Mar 27 22:35:47 rpi3 tvheadend[596]: webui: Couldn't start streaming /stream/channelnumber/101, No assigned adapters

It looks TVH can't find a service to tune to.

Please ensure that:

The Channel that you are trying to record has at least 1 active Service assigned.
That assigned Service comes from an active Mux.
That active Mux comes from an active Network.
That active Network is assigned to your 4K Adaptor.

eang

FIXED! The problem was that the I had another old service from another Mux assigned to the same channel (101). Once I deleted that service, it started working like a charm.

So I can happily confirm that the Raspberry TV HAT supports 4K channels!