Basic Question Regarding HDHR Flex 4K

ATSC 3.0 Forum
Post Reply
RickD_99
Posts: 8
Joined: Thu Jun 23, 2022 7:18 am

Basic Question Regarding HDHR Flex 4K

Post by RickD_99 »

Greetings all noob here who has the HDHR Flex 4K on the way from Amazon. A couple of my local stations here in my Birmingham Alabama DMA are commencing ATSC 3.0 transmissions today and tomorrow and I wanted to check them out in their early days.

Since the Flex 4K device is network based in design I presume it converts OTA broadcast transport streams to IP packets correct? If so does this conversion process alter or degrade the received OTA signal at all? I plan on using the Flex 4K with the iOS app on my Apple TV 4K box. Should I expect to see the same picture quality of an ATSC 3.0 broadcast on my Apple TV 4K as I would expect to see if the Flex 4K had a direct HDMI connection to my TV?

nickk
Silicondust
Posts: 18778
Joined: Tue Jan 13, 2004 9:39 am
x 154

Re: Basic Question Regarding HDHR Flex 4K

Post by nickk »

RickD_99 wrote: Thu Jun 23, 2022 7:45 am Since the Flex 4K device is network based in design I presume it converts OTA broadcast transport streams to IP packets correct? If so does this conversion process alter or degrade the received OTA signal at all? I plan on using the Flex 4K with the iOS app on my Apple TV 4K box. Should I expect to see the same picture quality of an ATSC 3.0 broadcast on my Apple TV 4K as I would expect to see if the Flex 4K had a direct HDMI connection to my TV?
The HDHomeRun FLEX 4K passes the HEVC encoded video through unmodified - there is no loss in quality.

Nick

RLKyle
Posts: 1
Joined: Sun Jun 26, 2022 4:55 am

Re: Basic Question Regarding HDHR Flex 4K

Post by RLKyle »

So far my Flex 4k does not detect any ATSC 3.0 channels in the Birmingham AL area.

Rich - since you are in my area are any 3.0 stations available? I'm getting 50+ ATSC channels.

RickD_99
Posts: 8
Joined: Thu Jun 23, 2022 7:18 am

Re: Basic Question Regarding HDHR Flex 4K

Post by RickD_99 »

RLKyle wrote: Mon Jul 25, 2022 4:41 am So far my Flex 4k does not detect any ATSC 3.0 channels in the Birmingham AL area.

Rich - since you are in my area are any 3.0 stations available? I'm getting 50+ ATSC channels.
Unfortunately no ATSC 3.0 telecasts so far. Originally they were supposed to begin June 23, then were delayed until July 14 supposedly. I did a scan on July 14 and again no sign of any HEVC 3.0 telecasting. A few of us have been following this on AVS forum….link is below if you are interested in joining:

https://www.avsforum.com/threads/birmin ... 9/page-242

ronj
Posts: 122
Joined: Mon Sep 05, 2022 2:17 pm
Device ID: 10A47292
x 9

Re: Basic Question Regarding HDHR Flex 4K

Post by ronj »

nickk wrote: Thu Jun 23, 2022 8:09 am The HDHomeRun FLEX 4K passes the HEVC encoded video through unmodified - there is no loss in quality.

Nick
Thanks for making that clear. Now can someone explain the audio piece of it? Or perhaps let me know if I'm correct in the following...

1. The audio is Dolby AC4
2. Very few devices support it (LG C7 and better TVs do, Apple TV 4K does not)
3. SiliconDust has some kind of proxy where they take the AC4 audio and transcode it to AC3 audio. Everything supports AC3.
4. The only issue it seems is that the proxy transcodes everything to 2 channel audio so I'm going to lose my surround sound (true DD 5.1 audio) because the proxy does not support it.

....is that all true?

.... So if I want true surround sound audio I need to ensure I'm not tuned to the ATSC 3.0 version of the broadcast and instead take the good old ATSC 1.0 version of it. Right?

DSperber
Posts: 247
Joined: Wed Dec 15, 2021 3:23 am
Device ID: 10A236FF
Location: Marina Del Rey, CA
x 5

Re: Basic Question Regarding HDHR Flex 4K

Post by DSperber »

ronj wrote: Mon Sep 05, 2022 2:22 pm 1. The audio is Dolby AC4
2. Very few devices support it (LG C7 and better TVs do, Apple TV 4K does not)
3. SiliconDust has some kind of proxy where they take the AC4 audio and transcode it to AC3 audio. Everything supports AC3.
4. The only issue it seems is that the proxy transcodes everything to 2 channel audio so I'm going to lose my surround sound (true DD 5.1 audio) because the proxy does not support it.

....is that all true?

.... So if I want true surround sound audio I need to ensure I'm not tuned to the ATSC 3.0 version of the broadcast and instead take the good old ATSC 1.0 version of it. Right?
All true. Some editorializing on the points can be made for clarification and explanation, but you've got it right.

In particular, the SD-created "cloud-assisted" transcoding involves a continuous online internet connection (a) to the cloud to provide the source AC4 DD5.1 audio for the decoding, and also (b) from the cloud back to the HDHR app to deliver the downmixed PCM 2.0 stereo. Then since the returned decoded stream is stereo it is either delivered to your AVR as that PCM 2.0 stereo, or "artificially now up-mixed into 5.1" by the HDHR app (which I call "faux 5.1") so that your AVR can send sound to multiple speakers. But it is NOT the true original AC4 DD5.1 six channels of audio going to your speakers.

If you want genuine true 5.1 audio given that no consumer AVR's today (that I know of) actually can decode AC4 even if it were possible to bitstream directly from the HDHR app to the AVR, the almost equivalent solution is, for example, to use the HDHR app running on an LG C7 or newer model. You would set the TV's audio output to HDMI-ARC and also "digital passthrough". The built-in AC-4 decoder in the LG C7+ is then used by the HDHR app to locally decode/transcode the AC4 DD5.1 into AC3 DD5.1. And the HDMI-ARC audio output with digital passthrough" audio setting on the C7+ causes the now AC3-DD5.1 to be bitstreamed to your AVR via ARC. The AC3 DD5.1 bitstream received by the AVR for handling is true AC3 DD5.1 developed (by the LG TV and its commercial licensed built-in Dolby AC-4 decoder) from the original ATSC 3.0 AC4 DD5.1 audio track and locally decoded by the LG C7+. No cloud assist, and no continuous online internet connection needed.

This is as close as we're going to get for a while anyway, unless/until AC4 handling (at a price of course) makes its way into consumer AVRs.

ronj
Posts: 122
Joined: Mon Sep 05, 2022 2:17 pm
Device ID: 10A47292
x 9

Re: Basic Question Regarding HDHR Flex 4K

Post by ronj »

DSperber wrote: Tue Sep 06, 2022 1:48 pm In particular, the SD-created "cloud-assisted" transcoding involves a continuous online internet connection (a) to the cloud to provide the source AC4 DD5.1 audio for the decoding, and also (b) from the cloud back to the HDHR app to deliver the downmixed PCM 2.0 stereo. Then since the returned decoded stream is stereo it is either delivered to your AVR as that PCM 2.0 stereo, or "artificially now up-mixed into 5.1" by the HDHR app (which I call "faux 5.1") so that your AVR can send sound to multiple speakers. But it is NOT the true original AC4 DD5.1 six channels of audio going to your speakers.
Thank you for that extremely clear and succinct description.
DSperber wrote: Tue Sep 06, 2022 1:48 pm If you want genuine true 5.1 audio ...
I do...in fact, it's a requirement (ok, that's a little strong) for me that might just cause me to choose the ATSC 1.0 channel instead. I'm in the Orlando market though and I'd rather just go ATSC 3.0 all the way.
DSperber wrote: Tue Sep 06, 2022 1:48 pm This is as close as we're going to get for a while anyway, unless/until AC4 handling (at a price of course) makes its way into consumer AVRs.
Bummer, but I get it.

So, why can't the SD-created "cloud-assisted" transcoding service transcode AC-4 5.1 into AC-3 5.1? Is it simply performance/scale related?

ronj
Posts: 122
Joined: Mon Sep 05, 2022 2:17 pm
Device ID: 10A47292
x 9

Re: Basic Question Regarding HDHR Flex 4K

Post by ronj »

DSperber wrote: Tue Sep 06, 2022 1:48 pm If you want genuine true 5.1 audio given that no consumer AVR's today (that I know of) actually can decode AC4 even if it were possible to bitstream directly from the HDHR app to the AVR, the almost equivalent solution is, for example, to use the HDHR app running on an LG C7 or newer model. You would set the TV's audio output to HDMI-ARC and also "digital passthrough". The built-in AC-4 decoder in the LG C7+ is then used by the HDHR app to locally decode/transcode the AC4 DD5.1 into AC3 DD5.1. And the HDMI-ARC audio output with digital passthrough" audio setting on the C7+ causes the now AC3-DD5.1 to be bitstreamed to your AVR via ARC. The AC3 DD5.1 bitstream received by the AVR for handling is true AC3 DD5.1 developed (by the LG TV and its commercial licensed built-in Dolby AC-4 decoder) from the original ATSC 3.0 AC4 DD5.1 audio track and locally decoded by the LG C7+. No cloud assist, and no continuous online internet connection needed.
I just realized that the TV I bought in 2016 is an LG C7! This is exactly what I'm going to do to pass the audio to my Sonos system. With your helpful description above I will get DD5.1 with ATSC 3.0 video quality after all! Thanks!

nickk
Silicondust
Posts: 18778
Joined: Tue Jan 13, 2004 9:39 am
x 154

Re: Basic Question Regarding HDHR Flex 4K

Post by nickk »

AC4 is supported on LG TVs that are 2019 and newer.

ronj
Posts: 122
Joined: Mon Sep 05, 2022 2:17 pm
Device ID: 10A47292
x 9

Re: Basic Question Regarding HDHR Flex 4K

Post by ronj »

nickk wrote: Wed Sep 07, 2022 8:18 am AC4 is supported on LG TVs that are 2019 and newer.
So I won't get it with an LG C7 sold in 2017??? Bummer..... but there are sites that do say Dolby AC-4 supported on this 2017 model...

https://www.flatpanelshd.com/lg_c7_oled_2017.php

... so I hope it works.

ronj
Posts: 122
Joined: Mon Sep 05, 2022 2:17 pm
Device ID: 10A47292
x 9

Re: Basic Question Regarding HDHR Flex 4K

Post by ronj »

Happy to report that Dolby AC-4 works natively on my 2017 model. The HDHR app sends the native AC-4 stream to it without first transcoding it and surround sound works well!

DSperber
Posts: 247
Joined: Wed Dec 15, 2021 3:23 am
Device ID: 10A236FF
Location: Marina Del Rey, CA
x 5

Re: Basic Question Regarding HDHR Flex 4K

Post by DSperber »

ronj wrote: Sat Nov 19, 2022 5:44 am Happy to report that Dolby AC-4 works natively on my 2017 model. The HDHR app sends the native AC-4 stream to it without first transcoding it and surround sound works well!
Correct.

As I had said back originally all LG OLED sets 2017 and newer (eg. the C7, which I myself have as well as a C9 from 2019) did support AC4 local decoding. I honestly don't know why Nick said it was 2019 or newer.

I get local AC4 decoding from the HDHR app running on BOTH my C7 and also C9.

Post Reply