AC-4 Audio?

ATSC 3.0 Forum
AzJazz
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AC-4 Audio?

Post by AzJazz »

Hi - I noticed that AC-4 was mentioned in the "Video but no sound" viewtopic.php?f=133&t=74253 topic.

Is all ATSC 3.0 audio encoded in AC-4?

If "yes", how can I play audio? AFAIK, I don't have an AC-4 decoder on my PC. My Onkyo TX-RZ730 doesn't support AC-4, either.

plnota
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Re: AC-4 Audio?

Post by plnota »

AC4 is the most common, some used AAC briefly for tests. I don't believe there are any current codecs available for PC, same with receivers. Will have to wait for them to become available - thus is the life of an early adopter. :lol:

NedS
Silicondust
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Re: AC-4 Audio?

Post by NedS »

We will probably start a thread and/or webpage to help track configurations and platforms that will work with AC-4. Most, if not all, Windows 10 systems should have some kind of path to support, Xbox One should be okay, recent LG smart TVs work, at least some Android TV devices should work (will need an update to the app, which is coming out soon), and various others that we need to test with and confirm. Plus, anything that can do passthrough audio through HDMI can add support using an AVR or soundbar with AC-4 support (anything that works with ATMOS should include AC-4 support).

That being said, at this point avoid buying anything specifically for AC-4 support until we get that list up, just to be safe. A lot of existing systems should be supported, and we don't want anyone buying something that ends up not working.

bgrubb1
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Re: AC-4 Audio?

Post by bgrubb1 »

There is a real need for this information
I am in the Phoenix market and thought I had no audio on HEVC due to the phoenix area timestamp problem
No audio on PC (with ATMOS driver) no audio on Nvidia Shield and no audio on Apple TV 4K
just out of boredom I installed the HD Homerun app on my 2020 LG TV and .... I have audio on HEVC
...Barry

jakep82
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Re: AC-4 Audio?

Post by jakep82 »

Audio is now working with the Channels DVR beta that was released today. I'm using a Chromecast with Google TV, and playback looks and sounds pretty good.

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

jakep82 wrote: Mon Oct 19, 2020 6:44 pm Audio is now working with the Channels DVR beta that was released today. I'm using a Chromecast with Google TV, and playback looks and sounds pretty good.
I'm getting audio and video via Channels DVR (beta) as well on my ATV and iPhone; however the video stops and starts a lot and the audio along with it, and sometimes at a much higher pitch...

though
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Re: AC-4 Audio?

Post by though »

jakep82 wrote: Mon Oct 19, 2020 6:44 pm Audio is now working with the Channels DVR beta that was released today. I'm using a Chromecast with Google TV, and playback looks and sounds pretty good.
Are you talking about the "Live Channels" app by Google found on ATV devices?

jxxaxxy
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Re: AC-4 Audio?

Post by jxxaxxy »

Nope Channels as in Channels DVR

https://getchannels.com/

though
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Re: AC-4 Audio?

Post by though »

jxxaxxy wrote: Tue Oct 20, 2020 9:09 am Nope Channels as in Channels DVR

https://getchannels.com/
Thanks for clarifying.

jakep82
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Re: AC-4 Audio?

Post by jakep82 »

darcilicious wrote: Mon Oct 19, 2020 8:24 pm
jakep82 wrote: Mon Oct 19, 2020 6:44 pm Audio is now working with the Channels DVR beta that was released today. I'm using a Chromecast with Google TV, and playback looks and sounds pretty good.
I'm getting audio and video via Channels DVR (beta) as well on my ATV and iPhone; however the video stops and starts a lot and the audio along with it, and sometimes at a much higher pitch...
I can't respond to your PM, and you may have already figured this out, but you need the client beta and not the server beta. You install it from within the Channels app, at least on Android. On the settings page you'll see an option to install the beta.

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

Thanks for the follow up. Unfortunately, beta releases on iOS and tvOS have to come from the developer in a more direct way I believe, e.g. viaTestFlight or direct link. In any case I did check the settings area on the iOS app and did not spot anything that said “beta“ :-)

Thanks though!

swmarks
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Re: AC-4 Audio?

Post by swmarks »

jakep82 wrote: Tue Oct 20, 2020 12:14 pm
darcilicious wrote: Mon Oct 19, 2020 8:24 pm
jakep82 wrote: Mon Oct 19, 2020 6:44 pm Audio is now working with the Channels DVR beta that was released today. I'm using a Chromecast with Google TV, and playback looks and sounds pretty good.
I'm getting audio and video via Channels DVR (beta) as well on my ATV and iPhone; however the video stops and starts a lot and the audio along with it, and sometimes at a much higher pitch...
I can't respond to your PM, and you may have already figured this out, but you need the client beta and not the server beta. You install it from within the Channels app, at least on Android. On the settings page you'll see an option to install the beta.
I can confirm that I'm having the same starting/stopping/stuttering issues while trying to watch ATSC3 channels on the latest Channels beta. It almost seems like it's not buffering enough or something. I've got 100% signal quality on the ATSC3 channels in my city, so I don't think that's an issue. The Channels app is much more watchable than the HDHomeRun app, though, lol. That one chokes like it's not using hardware deciding or something.

peanutbutter71
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Re: AC-4 Audio?

Post by peanutbutter71 »

I have been using a 2 tuner HDHomerun with Linux with great success for years. I didn't realize that when ATSC 3.0 came out that there was no support for AC-4. I can't see support in FFMPEG or VLC, and I think Kodi depends on FFMPEG.

I was kind of a late adopter of ATSC 1.0, but I suspect maybe some similar things happened for early adopters of ATSC 1.0?

kyl416
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Re: AC-4 Audio?

Post by kyl416 »

Yeah, until an open source ac3 codec came along you needed to purchase a DVD codec for Windows like WinDVD or NVidia's PureVideo codec.

PCI ATSC tuner cards like ATI's HDTV Wonder and Hauppauge's WinTV-HD came with software for MPEG2 Video/AC3 audio decoding, but it was hardcoded so the codecs would only work with their viewer software and not with other DirectShow based software like Windows Media Player.
Last edited by kyl416 on Wed Oct 21, 2020 12:37 pm, edited 1 time in total.

mooninite
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Re: AC-4 Audio?

Post by mooninite »

I wonder how much Dolby paid the ATSC group and/or broadcasters to force AC-4. There was no reason to use a new codec when there's a million of them out there. The best one is FOSS and Royalty-Free - Opus.

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