AC-4 Audio?

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NTC
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Re: AC-4 Audio?

Post by NTC »

Gwilly7 wrote: Tue Dec 22, 2020 2:07 pm Denver just got the updated channels yesterday and of course neither my Sony X900H or my Tivo Stream 4k can play the sound. My Sony has an ATSC 3.0 tuner inside, but that is coming with a future update. Guessing the AC-4 support will not come until that update, hopefully I am wrong.
If the Sony X900H relies on the Android media player API, the TV will need to be on Android 10 (Q) or newer to support AC-4. It may come with the ATSC 3.0 tuner turning on, or separately.

ppasteur
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Re: AC-4 Audio?

Post by ppasteur »

NedS wrote: Tue Dec 22, 2020 2:18 pm
mooninite wrote: Tue Dec 22, 2020 10:54 am Wrong.

Atmos is a metadata extension to AC-3 and AC-4. It's not audio data. "Atmos" is not a standard of audio - it is not AC-4. I wish Nick would stop using Atmos in this way.

"DD" is AC-3 - and can contain Atmos data
"DD+" is a minor update to AC-3 with support for more bitrates. It's also known as E-AC-3. It can also contain Atmos data.
Hardware and software licensed for ATMOS will be licensed for AC-4. Atmos is the feature that gets advertised.
It is a bit more complicated than that, I think
This is from a Wikipedia article on AC-4:
"Dolby AC-4 is covered by patents and requires a license from Dolby Laboratories.[8] Dolby AC-4 has a consumer royalty rate of US$0.15 to US$1.20 depending on the type of device and volume of sales.[8] Dolby only charges for one technology per device, which means that Dolby AC-4 effectively costs nothing in devices that include existing Dolby technologies such as Dolby Digital Plus."

In reading this I think that, while AC-4 will be covered by licensing a device for Atmos (or EAC-3/DD+), this does not mean that the codec/implementation for AC-4 will be available in all devices licensed to use it.

wriede
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Re: AC-4 Audio?

Post by wriede »

After the recent changes the HDHomeRun app on my NVidia Shield Pro (2020) now feeds sound to my Atmos capable Denon X3600H. Progress!

However, after watching either Phoenix's 15.1 or 61.1 video and sound become a little jerky - short hesitations. It's like something is not quite able to keep up...

Gwilly7
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Re: AC-4 Audio?

Post by Gwilly7 »

NTC wrote: Wed Dec 23, 2020 11:14 am
Gwilly7 wrote: Tue Dec 22, 2020 2:07 pm Denver just got the updated channels yesterday and of course neither my Sony X900H or my Tivo Stream 4k can play the sound. My Sony has an ATSC 3.0 tuner inside, but that is coming with a future update. Guessing the AC-4 support will not come until that update, hopefully I am wrong.
If the Sony X900H relies on the Android media player API, the TV will need to be on Android 10 (Q) or newer to support AC-4. It may come with the ATSC 3.0 tuner turning on, or separately.
Thank you, hopefully Sony comes out with the Android 10 update sooner then later.

ppasteur
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Re: AC-4 Audio?

Post by ppasteur »

wriede wrote: Wed Dec 23, 2020 4:12 pm After the recent changes the HDHomeRun app on my NVidia Shield Pro (2020) now feeds sound to my Atmos capable Denon X3600H. Progress!

However, after watching either Phoenix's 15.1 or 61.1 video and sound become a little jerky - short hesitations. It's like something is not quite able to keep up...
I have a similar problem with my Shield 2019 PRO in Denver. It happens with all of the ATSC 3 signals (except 2.1 where, the last I checked, there is just no audio at all).
The Shield 2019 PRO has some problem with audio, but the video stream continues while the audio drops out for seconds at a time. When it restarts it is in sync with the video.
It almost seems like some sort of buffering problem. But, I would think audio would be less of an issue than video were that the case.

I am using Version 20201212 on the Shield and Version 20201030 on the Quatro 4K.

Williams
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Re: AC-4 Audio?

Post by Williams »

After my latest round of testing today, I am optimistic AC-4 audio will eventually become widely supported on existing platforms. I tested the following hardware and software and got the following results.

- 2014 Mac mini OS X 10.13 which is a dedicated media center / streaming box - video in both the HDHR app from the 20201030 software and in Kodi 18.9. No audio in either. I don't recall if I was able to select the SAP in the HDHR app. In Kodi, the audio settings says none so FFMPEG is not recognizing the audio track at all

- 2020 iPad Air 4 latest iOS 14 - video in 20201221 (UI) HDHR app. No audio but I get momentary sound when I toggle the SAP.

- iPhone XS latest iOS 14 - no video in the 20201221 (UI) HDHR app. I had it playing audio for many seconds but after tuning to the different ATSC 3 stations the audio only played for a second or two before nothing. The app didn't crash it just stayed on a black screen with no audio.

- Late 2013 MacBook Pro on Windows 10 (2H20) and the HDHR app (updated by the Windows Store on 12/21 when I logged in to test). All four ATSC 3 stations I can receive in Denver (CW, NBC, FOX, ABC) had working audio and video. I only watched them for a couple of minutes at most since I don't run Windows for home use and was testing. During those short viewings, everything was stable. I am running Mac OS X 10.14 for daily use and only video works in the 20201030 HDHR app.

The fact I have audio and video from a 7-year old laptop on the ATSC 3 stations in Windows makes me think that it's just a matter of making incremental progress to get audio working on most of the other major media players and platforms. As mentioned by the folks at SD who are a lot closer to the broadcast industry and technology, it is very early days. All of us consumers tuning into the ATSC 3 signals are testing right now alongside the receiver manufactures and broadcasters.

I am therefore holding off buying new equipment that's further along in the audio/video working phase or setting up a Windows 10 media center from scratch on the Mac mini (the mini will eventually go Windows though due to Apple moving away from Intel CPUs).
Last edited by Williams on Thu Dec 24, 2020 11:21 pm, edited 1 time in total.

KU7PDX
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Re: AC-4 Audio?

Post by KU7PDX »

FFantin wrote: Sat Dec 19, 2020 2:22 pm I'd suggest not buying the Roku Ultra 2020. I just got it today under the impression that it does support AC-4, but it doesn't work and I'm going to return the device immediately.
I can confirm that the Roku Ultra 2020 does indeed support AC-4. Silicondust needs to update their Roku app to update the support for AC-4.

kyl416
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Re: AC-4 Audio?

Post by kyl416 »

KU7PDX wrote: Thu Dec 24, 2020 11:11 pm I can confirm that the Roku Ultra 2020 does indeed support AC-4. Silicondust needs to update their Roku app to update the support for AC-4.
While the Roku Ultra 2020 has AC-4 support, their player only supports it within a mp4 container, and not within a mpeg-ts container which is what live broadcast streams use.

RonRN18
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Re: AC-4 Audio?

Post by RonRN18 »

kyl416 wrote: Thu Dec 24, 2020 11:32 pm
KU7PDX wrote: Thu Dec 24, 2020 11:11 pm I can confirm that the Roku Ultra 2020 does indeed support AC-4. Silicondust needs to update their Roku app to update the support for AC-4.
While the Roku Ultra 2020 has AC-4 support, their player only supports it within a mp4 container, and not within a mpeg-ts container which is what live broadcast streams use.
This is just a curiousity, as I do not currently have ATSC 3.0 being broadcasted in my area to find out, but if I were to use Plex to record an ATSC 3.0 broadcast with AC-4 audio, would this MPEG-TS file be able to be converted to an MP4 or MKV container with FFMPEG? I realize that FFMPEG does not currently transcode AC4 audio, but can it copy it into the container? If so, would that allow the playback on the Roku Ultra 2020?

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

Unfortunately no, then Plex server doesn’t pass through unknown codecs (which is what AC4 is to Plex).

Aubury
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Re: AC-4 Audio?

Post by Aubury »

darcilicious wrote: Sun Dec 27, 2020 7:13 am Unfortunately no, then Plex server doesn’t pass through unknown codecs (which is what AC4 is to Plex).
It's a shame, too.

All my local main broadcast stations all started broadcasting ATSC 3.0 at the same time, and the HDHR app on my Nvidia Shield Pro keeps crashing when I try to tune the ATSC 3.0 stations. I get video no problem with Plex, but like you said it doesn't even pass through the unknown codec which I know my TV can play cause I get audio from the HDHR app about a second before it crashes. Looks like there's been some work done on adding AC-4 support to ffmpeg, but still going to take a little while before its mainlined and then we have to wait for Plex to update their copy of ffmpeg to the new version.

vanhln
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Re: AC-4 Audio?

Post by vanhln »

Can anyone confirm that the HDHomerun Connect 4K works well with ATSC 1.0 on Plex now?

I'll worry about ATSC 3.0 when Cleveland officially broadcasts which is upcoming. I'd like to upgrade the 2 tuners on my HDHomerun Extend to four on the Connect 4k in the short-term....

signcarver
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Re: AC-4 Audio?

Post by signcarver »

Works fine until one actually has ATSC 3.0. The upcoming (supposedly this week) firmware "should" fix it for it to be possible to use ATSC 1.0 if ATSC 3,0 is present.

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

signcarver wrote: Sun Dec 27, 2020 5:30 pm Works fine until one actually has ATSC 3.0. The upcoming (supposedly this week) firmware "should" fix it for it to be possible to use ATSC 1.0 if ATSC 3,0 is present.
From what SD posted earlier about their approach, it will take both a firmware update (on the tuner) AND an application update (aka app "awareness"), said Nick here: viewtopic.php?p=366930#p366930

vanhln
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Re: AC-4 Audio?

Post by vanhln »

Thanks.. I know the FFMpeg update is important also.. I do need more tuners so considering the connect 4k... Err by app awareness.. that prolly means Plex... I'm a patient man, so will still probably get the hardware at some point....

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