Mailing List Archive

On Sat, Jun 10, 2023 at 6:30?PM Ken Mandelberg <km@mathcs.emory.edu> wrote:

> I'm trying to understand 4K TV. I'm in the US and use Xfinity,
> independently with MythTV via HDHomerun cable box, and for On Demand and
> SVOD their X1 DVR.
>
> I have been happy with my 40" 1920x1080 native TV and have been ignoring
> 4K, but recently I experimented with a projector with the same HD native
> resolution projecting a 90" diagonal image. It was OK, but at that size
> from 7 feet away the sharpness defintely was a bit disappointing. I
> presume that no matter what the source that projector's resolution would
> be a limitation.
>
> That made me wonder if even with a higher native res projector, or a
> larger 4K TV whether the media would become the limitation. That raised
> the questions
>
> * What 4K programming is there over Xfinity cable. Is it just a few
> premium channels and no broadcast networks.
>
> * Can the HDHomerun Cablecard box deliver "ts" files at 4K resolution?
>
> * Can the mythfrontend on Linux generate 4K HDMI output from the ts files?
>
> * Same question for Leanfront on a 4K firestick.
>
>
Cable TV has been scrambling to hold on to their viewers. I think you may
be the last one I know of :-)

Around here a lot of cable TV guys are only supplying the Internet and have
a streaming app for what they used to offer with a cable box.

Most cable boxes I know of don't do 4K and most cheat at 1080i compared to
over the air.

mthfrontend doesn't do 4K AFAIK. However, on my UHD 4K TV I have connected
a PC running 4k that uses its own image enhancement to improve the quality
of the original HD signal. At least I think it does. Looks great.

Leanfront on the Firetv is the best picture I get from mythtv, but the
original content is only HD, so it's good, but technically not 4K. Firetv
does great with 4K sources like NetFlix, etc.

Jim A

On 6/10/23 16:13, James Abernathy wrote:
>
>
> On Sat, Jun 10, 2023 at 6:30?PM Ken Mandelberg <km@mathcs.emory.edu> wrote:
>
> I'm trying to understand 4K TV. I'm in the US and use Xfinity,
> independently with MythTV via HDHomerun cable box, and for On Demand and
> SVOD their X1 DVR.
>
> I have been happy with my 40" 1920x1080 native TV and have been ignoring
> 4K, but recently I experimented with a projector with the same HD native
> resolution projecting a 90" diagonal image. It was OK, but at that size
> from 7 feet away the sharpness defintely was a bit disappointing. I
> presume that no matter what the source that projector's resolution would
> be a limitation.
>
> That made me wonder if even with a higher native res projector, or a
> larger 4K TV whether the media would become the limitation. That raised
> the questions
>
> * What 4K programming is there over Xfinity cable. Is it just a few
> premium channels and no broadcast networks.
>
> * Can the HDHomerun Cablecard box deliver "ts" files at 4K resolution?
>
> * Can the mythfrontend on Linux generate 4K HDMI output from the ts files?
>
> * Same question for Leanfront on a 4K firestick.
>
>
> Cable TV has been scrambling to hold on to their viewers.  I think you may be the last one I know of :-)
>
> Around here a lot of cable TV guys are only supplying the Internet and have a streaming app for what they used to offer with a
> cable box.
>
> Most cable boxes I know of don't do 4K and most cheat at 1080i compared to over the air.
>
> mthfrontend doesn't do 4K AFAIK.  However, on my UHD 4K TV I have connected a PC running 4k that uses its own image
> enhancement to improve the quality of the original HD signal. At least I think it does. Looks great.
>
> Leanfront on the Firetv is the best picture I get from mythtv, but the original content is only HD, so it's good, but
> technically not 4K.  Firetv does great with 4K sources like NetFlix, etc.
>
> Jim A
>
>
>
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4 K so for is only available via streaming, or 4K bluray disks.

ATSC 3.0 is supposed to support 4K over the air, but so far I have not seen any broadcast.

But even if you have a tuner that supports ATSC 3.0, (HDHomeRun), and stations in your area are broadcasting ATSC 3.0, mythtv
seems to ignore them. Even though manually scanned with HDHomeRun Config, they show up, and my TV gets them, mythTV misses them
in the channel scan. I do not know if this is a deliberate decision or a bug.

On Sat, Jun 10, 2023 at 6:30?PM Ken Mandelberg <km@mathcs.emory.edu> wrote:

> * What 4K programming is there over Xfinity cable. Is it just a few
> premium channels and no broadcast networks.

Basically none (the occasional sporting event,
and an occasional "stunt" program). I believe
all "4K" content on Xfinity is now transmitted via
IPTV (not linear QAM), although some early
stunts may have been linear QAM,

While some shows are filmed in "4K", pretty
much none of the channels (or stations) production
equipment sends out "4K".

> * Can the HDHomerun Cablecard box deliver "ts" files at 4K resolution?

If there was any, yes (the tuner just sends the
bits it receives on to the host).

> * Can the mythfrontend on Linux generate 4K HDMI output from the ts files?

Often that depends more on the GPU card
decode capabilities for the codec being
used.
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On Sat, Jun 10, 2023 at 7:39?PM Douglas Peale <Douglas_Peale@comcast.net> wrote:

> ATSC 3.0 is supposed to support 4K over the air, but so far I have not seen any broadcast.
>
> But even if you have a tuner that supports ATSC 3.0, (HDHomeRun), and stations in your area are broadcasting ATSC 3.0, mythtv seems to ignore them. Even though manually scanned with HDHomeRun Config, they show up, and my TV gets them, mythTV misses them in the channel scan. I do not know if this is a deliberate decision or a bug.

MythTV only supports the http streaming protocol
that is needed for ATSC 3.0 with the SiliconDust
tuners with a 3rd party external recorder, or using
the IPTV tuner source (which may require the
latest master release).

Note that because almost all ATSC 3.0 transmitters
are shared and broadcasting multiple stations none
of the content is "4K"(*) (occasional short term
stunts in Las Vegas in January excepted), as you
can only fit so many bits into 6MHz, even with
OFDM, although some stations move up to 1080p
from 1080i, so there may be some PQ improvements,

Regular "4K" via ATSC 3.0 OTA is likely a ways
off, and there is also the protected content path
requirement that is being implemented by
many OTA ATSC3.0 stations.


(*) And, remember, there is a dearth of "4K"
content available to the OTA stations.
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On 6/10/23 18:28, Ken Mandelberg wrote:
> * Can the mythfrontend on Linux generate 4K HDMI output from the ts
> files?
yes
>
> * Same question for Leanfront on a 4K firestick.

yes

Note - mythfrontend on firestick 4K will not render 4K resolution.

Peter


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On Sun, 11 Jun 2023 at 02:07, Gary Buhrmaster <gary.buhrmaster@gmail.com>
wrote:

> On Sat, Jun 10, 2023 at 7:39?PM Douglas Peale <Douglas_Peale@comcast.net>
> wrote:
>
> > ATSC 3.0 is supposed to support 4K over the air, but so far I have not
> seen any broadcast.
> >
> > But even if you have a tuner that supports ATSC 3.0, (HDHomeRun), and
> stations in your area are broadcasting ATSC 3.0, mythtv seems to ignore
> them. Even though manually scanned with HDHomeRun Config, they show up, and
> my TV gets them, mythTV misses them in the channel scan. I do not know if
> this is a deliberate decision or a bug.
>
> MythTV only supports the http streaming protocol
> that is needed for ATSC 3.0 with the SiliconDust
> tuners with a 3rd party external recorder, or using
> the IPTV tuner source (which may require the
> latest master release).
>
>
The latest master now supports importing the channels from the HDHomeRun
directly. This then stores the URL for each channel and with the IPTV tuner
connected to the HDHomeRun video source all available channels including
the ATSC3.0 channels can be received.
With the IPTV capture card you can also import the m3u file directly from
the HDHomeRun.
See the Wiki page
https://www.mythtv.org/wiki/Channel_Scanning#HDHomeRun_Channel_Import_2 for
a detailed description.
BUT... the ATSC3.0 UHD/4K broadcast does use AC4 audio coding and that is
not supported in mythtv. Playing back recordings should be OK but video
only....

Klaas.

On Sun, Jun 11, 2023 at 3:42?AM Klaas de Waal <klaas.de.waal@gmail.com> wrote:

> BUT... the ATSC3.0 UHD/4K broadcast does use AC4 audio coding and that is not supported in mythtv. Playing back recordings should be OK but video only....

ATSC 3.0 is a work in progress. Don't expect it
to work seamlessly (or at all) for any specific
use case.

Some stations still use AC-3 for audio, and some
NextGen (ATSC 3.0) TV's can decode AC-4 and
output sound (via build-in speakers or HDMI ARC),
when fed via HDMI (although some TV's reportedly
only support the decode when fed by the tuner)
and reportedly a few relatively new A/V receivers
may have some support (leveraging their Atmos
support, as AC-4 and Atmos share a lot of
tech).

Given the requirements for the IP encumbered
codec, a lot of solutions are waiting for the
usual OS suspects to license and integrate
the codec directly into their platform eliminating
some complexity for playback. There are always
rumors that Android, iOS/tvOS/macOS, and
Windows might add such support real soon now
given some already support Atmos.

And it should be noted that ATSC 3,0 also
tends to use H.265 video, which is not
universally supported at TV rates across
all MythTV systems if one needs to fall
back to software decode because your
GPU does not support it (although, as
with audio, some stations use lower
complexity codecs).

ATSC 3.0 is still (including to the station
owners) somewhat of a work in progress,
and it is not at all clear when the original
promise will be seen (and, to add to the
future alternatives, a number of station
owners have joined a consortium whose
purpose is to research other methods to
monetize the ATSC 3.0 channel which
does not include just TV programming).
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On 11/06/2023 08:41, Klaas de Waal wrote:
>
>
> On Sun, 11 Jun 2023 at 02:07, Gary Buhrmaster
> <gary.buhrmaster@gmail.com> wrote:
>
> On Sat, Jun 10, 2023 at 7:39?PM Douglas Peale
> <Douglas_Peale@comcast.net> wrote:
>
> > ATSC 3.0 is supposed to support 4K over the air, but so far I
> have not seen any broadcast.
> >
> > But even if you have a tuner that supports ATSC 3.0,
> (HDHomeRun), and stations in your area are broadcasting ATSC 3.0,
> mythtv seems to ignore them. Even though manually scanned with
> HDHomeRun Config, they show up, and my TV gets them, mythTV misses
> them in the channel scan. I do not know if this is a deliberate
> decision or a bug.
>
> MythTV only supports the http streaming protocol
> that is needed for ATSC 3.0 with the SiliconDust
> tuners with a 3rd party external recorder, or using
> the IPTV tuner source (which may require the
> latest master release).
>
>
> The latest master now supports importing the channels from the
> HDHomeRun directly. This then stores the URL for each channel and with
> the IPTV tuner connected to the HDHomeRun video source all available
> channels including the ATSC3.0 channels can be received.
> With the IPTV capture card you can also import the m3u file directly
> from the HDHomeRun.
> See the Wiki page
> https://www.mythtv.org/wiki/Channel_Scanning#HDHomeRun_Channel_Import_2
> for a detailed description.
> BUT... the ATSC3.0 UHD/4K broadcast does use AC4 audio coding and that
> is not supported in mythtv. Playing back recordings should be OK but
> video only....
>
> Klaas.
>

For reference we would need AC4 support in ffmpeg to be able to play the
audio. There is a patch to add support but as always the ffmpeg devs are
slow to commit or even provide feedback for the patch :(

https://trac.ffmpeg.org/ticket/8349


Paul H.

On 6/11/23 4:34 AM, Gary Buhrmaster wrote:
> On Sun, Jun 11, 2023 at 3:42?AM Klaas de Waal <klaas.de.waal@gmail.com> wrote:
>
>> BUT... the ATSC3.0 UHD/4K broadcast does use AC4 audio coding and that is not supported in mythtv. Playing back recordings should be OK but video only....
> ATSC 3.0 is a work in progress. Don't expect it
> to work seamlessly (or at all) for any specific
> use case.
>
> Some stations still use AC-3 for audio, and some
> NextGen (ATSC 3.0) TV's can decode AC-4 and
> output sound (via build-in speakers or HDMI ARC),
> when fed via HDMI (although some TV's reportedly
> only support the decode when fed by the tuner)
> and reportedly a few relatively new A/V receivers
> may have some support (leveraging their Atmos
> support, as AC-4 and Atmos share a lot of
> tech).
>
> Given the requirements for the IP encumbered
> codec, a lot of solutions are waiting for the
> usual OS suspects to license and integrate
> the codec directly into their platform eliminating
> some complexity for playback. There are always
> rumors that Android, iOS/tvOS/macOS, and
> Windows might add such support real soon now
> given some already support Atmos.
>
> And it should be noted that ATSC 3,0 also
> tends to use H.265 video, which is not
> universally supported at TV rates across
> all MythTV systems if one needs to fall
> back to software decode because your
> GPU does not support it (although, as
> with audio, some stations use lower
> complexity codecs).
>
> ATSC 3.0 is still (including to the station
> owners) somewhat of a work in progress,
> and it is not at all clear when the original
> promise will be seen (and, to add to the
> future alternatives, a number of station
> owners have joined a consortium whose
> purpose is to research other methods to
> monetize the ATSC 3.0 channel which
> does not include just TV programming).
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@mythtv.org
> http://lists.mythtv.org/mailman/listinfo/mythtv-users
> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org

For a reference point.  I have an HD Homerun with ATSC 3.0 tuners. 
Originally, the HD Homerun app on my android tablet would list the
channels, but fail to play them.  Recently, it now plays them with
sound.  So android at least supports this.  Also, my LG TV has support
for HD homerun tuners and will also play the ATSC 3.0 channels with
sound.  What I don't know is if the TV is decoding the audio or my AV
receiver (TV is connected to the receiver via TOslink (SPDIF)).

Still on linux, vlc will play the video but no audio, so I know that the
ATSC 3.0 station is using AC4 audio.

Jay

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On Sun, Jun 11, 2023 at 1:02?PM Jay Foster <jayf0ster@roadrunner.com> wrote:

> For a reference point. I have an HD Homerun with ATSC 3.0 tuners.
> Originally, the HD Homerun app on my android tablet would list the
> channels, but fail to play them. Recently, it now plays them with
> sound. So android at least supports this.

SiliconDust has a cloud based transcoder for
AC-4 (currently to stereo as I recall) for
presentation devices which do not support
AC-4 natively (which devices support AC-4
can vary, even over software releases),
so if one is using SD's ecosystem AC-4
sound works.
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