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Feature #6023

ATSC 3.0 Mux support for US markets.

Added by Alan Z. over 1 year ago. Updated 3 months ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
DVB
Target version:
-
Start date:
2021-03-15
Due date:
% Done:

0%

Estimated time:

Description

Is there a possibility for the new ATSC 3.0 standard to be added to the pre-defined muxes?

Configuration -> DVB Inputs -> Networks -> Edit network -> Pre-defined muxes.


Files

tvhhdhriptvnetwork (1.45 KB) tvhhdhriptvnetwork Michael Marley, 2021-12-12 17:23

History

#1

Updated by saen acro over 1 year ago

This standard is so unpopular
https://git.linuxtv.org/dtv-scan-tables.git/tree/atsc

dtv-scan-tables package need to include them

I wasn't search for tutorials how to scan this exotical standard used in 3 countries in world, but maby there is.

#2

Updated by Alan Z. over 1 year ago

The ATSC3.0 (HEVC) is a new OTA standard in the US (as of February 2021), that supports up to 4K resolutions. There are already some stations available, that use it.

#3

Updated by Flole Systems over 1 year ago

  • Category changed from Muxers to DVB

If you (or someone else) submit a PR it will be considered for merging, just like every other PR. For obvious reasons someone who is in a region that uses it should do that, everything else would be super slow and inefficient.

#4

Updated by saen acro over 1 year ago

Alan Z. wrote:

The ATSC3.0 (HEVC) is a new OTA standard in the US (as of February 2021), that supports up to 4K resolutions. There are already some stations available, that use it.

HEVC (video coding) noting to do with Transportation technology on similar standards.
ATSC3.0 will make TV hardware change with is nonsense.

ATSC 3.0 (Advanced Television Systems Committee) is a digital terrestrial broadcasting standard that has been substantially enhanced compared with the ATSC A/53 predecessor standard. ATSC 3.0 is designed to allow network operators more flexibility, greater robustness and more efficient operation. It employs state-of-the-art encoding and modulation technologies, enabling a significantly more effective use of the limited spectrum resources. In this way, capacity is created to transfer UHD video contents and immersive audio contents to the end user via terrestrial channels with minimal resources. The consistent focus on IP technology in the baseband makes it possible to merge cost-effective terrestrial broadcasting with other IP-based services.

ATSC 3.0 is the first ATSC standard to employ coded orthogonal frequency division multiplexing (COFDM). This modulation method uses a large number of orthogonal carriers, resulting in a signal that is robust against jamming. COFDM technology also makes it possible to set up spectrum-efficient ATSC 3.0 single-frequency networks (SFN).

Use of the latest low density parity check (LDPC) codes in combination with Bose-Chaudhuri-Hocquenghem (BCH) codes allows the usable channel capacity to approach the theoretical Shannon limit, as does the use of non-uniform constellations (NUC) for modulation. ATSC 3.0 employs multiple physical layer pipe (multiple PLP) technology, enabling a flexible use of the channel. With the latest technologies such as Layer Division Multiplexing (LDM), an effective simultaneous crossover can be realized both for mobile reception and for stationary reception.

DVB-T2 is still better ;) read comparsion betwin both

#5

Updated by Alan Z. over 1 year ago

I have the HDHomeRun CONNECT 4K tuner, so if it could be used somehow to get needed information I would help to provide more details. I can't see anything useful from the device's menu, except for the channel frequencies.

#6

Updated by Michael Marley 12 months ago

I've been doing some research and testing about this. There were similar questions asked over at MythTV and what they found is that the "libhdhomerun" interface that they and TVHeadend both use is deprecated and doesn't support setting the modulation as would be necessary to tune ATSC3. What they recommended was using the "mythhdhrrecorder" ExternalRecorder script, which just uses HTTP streaming from the HDHR using the "http://<HDHR_ADDRESS>:5004/auto/v5.1" URLs, which obviously operate by virtual channel number and repack the DASH/ROUTE encoding of the ATSC3 signal as a regular old MPEG TS. This method does, however, have the disadvantage that the HDHR isn't smart enough to reuse already-tuned muxes, for example, if you were already recording 5.1 and then started recording 5.2, it would use a second tuner for that instead of the existing tuner already tuned to the correct frequency.

TVHeadend thankfully already has most of what it needs to handle this type of streaming; you can just create an IPTV network and then add the virtual channel URLs as described above manually and it should work, whether for ATSC3 or ATSC1. (I don't have an HDFX-4K yet, so I can't test for sure.) I'm also going to look into the possibility of making TVHeadend able to parse the "http://<HDHR_ADDRESS>/lineup.json" endpoint for the "IPTV Auto" network type, which should in theory be able to automatically populate the list.

I also looked in to the possibility of working around the limitation I mentioned at the beginning of the first paragraph, and what I found is that it is also possible to construct a URL based on the physical channel (e.g. "http://<HDHR_ADDRESS>:5004/auto/ch599000000"). This of course returns the entire mux including all subchannels, which TVHeadend then identifies as separate services, allowing for watching/recording multiple services on a single mux with a single tuner (with some limitations until https://github.com/tvheadend/tvheadend/pull/1430 is merged). I'm not sure how this would react though if you used it to tune an ATSC3 mux; I couldn't find any information about this in the HDHR documentation or SiliconDust's forum. There's no reason you couldn't combine the virtual channels and the physical frequencies in the same IPTV network though, but that would of course have the same limitation for the ATSC3 channels as I described in the first paragraph.

I also wrote a shell script that parses the dvbscan data and makes service calls to TVHeadend to create an IPTV network and add all the frequencies with their physical channel URLs. The script is attached and of course must be modified for your specific configuration. Additionally, "curl" and "jq" must be installed for it to work.

#7

Updated by G C 11 months ago

I have used the same workaround but unfortunately you don't get sound on ATSC3 channels as they use AC-4 audio. So you can work around TVHeadend not seeing the MUXES but then all you get is a video stream.

Any ideas on the audio?

#8

Updated by Michael Marley 11 months ago

The missing audio is not the fault of TVHeadend (transcoding aside, TVHeadend is just storing the MPEG transport stream to disk without modification); it is because FFmpeg does not yet have support for AC-4: https://trac.ffmpeg.org/ticket/8349

#9

Updated by C M 3 months ago

Michael Marley, is your script still the best way of going about this? Just making sure a feature hasn't been added to TVH before continuing to try to use it.
I've set TVH_URL, USERNAME, PASSWORD, HDHR_HOSTNAME, and DTV_FILE_BASE according to my environment. I'm getting, "parse error: Invalid numeric literal at line 1, column 10"

Any idea what I'm doing wrong? I'm using Flex 4k, would providing the json output from it help?

Thanks for sharing the script!

#10

Updated by Michael Marley 3 months ago

I apologize, I'm not sure what could be causing it to crash like that. The only thing on line 1 is the hashbang, so the script interpreter shouldn't be processing that at all.

#11

Updated by C M 3 months ago

I'm getting output from CURL (I think) downloading the file to parse first. I'm thinking the error is maybe the first line that JQ tries to parse? I'm pretty green with regex, json, and shell scripting but I'm trying.
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 535 100 432 100 103 396k 96804 --:--:-- --:--:-- --:--:-- 522k
parse error: Invalid numeric literal at line 1, column 10

#12

Updated by C M 3 months ago

Got it. TVH "Authentication type:" was set to digest, needs to include "plain". It was giving an error 401. Thanks again for sharing the script, not sure if I'll end up using this setup but I wanted to test it for learning purposes at least.

#13

Updated by C M 3 months ago

This is for the record, because you mentioned not having a Flex 4k. My market has 4 ATSC3 stations and they all seem to be on the same channel (frequency, not virtual channel). The script pulled in the muxes and all the ATSC1 channels got services. The mux with the ATSC3 channels says scan result is 'FAIL'. Is there anything I could tweak to get TVH to find the ATSC3 services?

#14

Updated by Michael Marley 3 months ago

You'll probably need to manually add them using the virtual channel numbers as opposed to the frequencies.

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