AC-4 Audio?

ATSC 3.0 Forum
kyl416
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Re: AC-4 Audio?

Post by kyl416 »

peanutbutter71 wrote: Wed Oct 21, 2020 9:20 pm Should we start a gofundme to get someone to write it for FFMPEG?
There is a site Bountysource where you can contribute to a "bounty" towards resolving a bug/feature request. It's supported by the FFmpeg team and integrated with their issue tracker, so pages on Bountysource are already available for each issue.

Here's their entry for the AC-4 issue:
https://www.bountysource.com/issues/831 ... -4-support

Another open issue that affects ATSC 3.0 is the lack of support for interlaced HEVC that some stations are using, so these stations currently appear as 1920x540p instead of 1920x1080i in VLC:
https://www.bountysource.com/issues/655 ... -1920x540p
Last edited by kyl416 on Thu Oct 22, 2020 2:55 pm, edited 1 time in total.

demonrik
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Re: AC-4 Audio?

Post by demonrik »

kyl416 wrote: Wed Oct 21, 2020 9:58 pm Another open issue that affects ATSC 3.0 is the lack of support for deinterlaced HEVC that some stations are using, so these stations currently appear as 1920x540p instead of 1920x1080i in VLC:
https://www.bountysource.com/issues/655 ... -1920x540p
This is extraction of SEI information for SAFF (sequence adaptive field frame)
Basically the decoder needs to decode the SEI and realize each 540p picture is 1 field and then reconstruct by interleaving the scanlines and creating the final picture.
I wish content producers would just face reality and stop retro-fitting interlaced on to displays..
Anyway - downside is no HW decoder is gonna support this crap, so it's gonna be SW and that is just asking for performance problems.

kc9pke
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Re: AC-4 Audio?

Post by kc9pke »

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...
Which iPhone? I have an 11, just waiting for 3.0 to come to my area

peanutbutter71
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Re: AC-4 Audio?

Post by peanutbutter71 »

kyl416 wrote: Wed Oct 21, 2020 9:58 pm
peanutbutter71 wrote: Wed Oct 21, 2020 9:20 pm Should we start a gofundme to get someone to write it for FFMPEG?
There is a site Bountysource where you can contribute to a "bounty" towards resolving a bug/feature request. It's supported by the FFmpeg team and integrated with their issue tracker, so pages on Bountysource are already available for each issue.

Here's their entry for the AC-4 issue:
https://www.bountysource.com/issues/831 ... -4-support

Another open issue that affects ATSC 3.0 is the lack of support for interlaced HEVC that some stations are using, so these stations currently appear as 1920x540p instead of 1920x1080i in VLC:
https://www.bountysource.com/issues/655 ... -1920x540p
I thought ATSC 3.0 would finally abandon interlacing for good!?!

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

kc9pke wrote: Thu Oct 22, 2020 2:52 pm
darcilicious wrote: Mon Oct 19, 2020 8:24 pm 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...
Which iPhone? I have an 11, just waiting for 3.0 to come to my area
iPhone 11 Pro; not watchable really, with the HDHomeRun app but it tries really hard ;)

Vogateer
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Re: AC-4 Audio?

Post by Vogateer »

I can't believe I wasted money on this new tuner. I expect some issues with new tech, but not being able to play audio anywhere isn't just a minor issue. It defeats the whole purpose.

nickk
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Re: AC-4 Audio?

Post by nickk »

We have submitted apps for iOS and AppleTV adding ATSC 3.0 playback support.

They will hopefully be accepted and be available to install in a few days.

Nick

darcilicious
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Re: AC-4 Audio?

Post by darcilicious »

nickk wrote: Thu Oct 29, 2020 7:14 pm We have submitted apps for iOS and AppleTV adding ATSC 3.0 playback support.

They will hopefully be accepted and be available to install in a few days.

Nick
Yay, thanks for the update!

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Re: AC-4 Audio?

Post by ebo »

For the next ATSC 3.0 HDHR model, or even the current one if it's possible with a firmware change, it would be good to add an option to transcode AC-4 audio to a format that most digital audio players can deal with. AC-3, E-AC-3, even PCM would do.

NedS
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Re: AC-4 Audio?

Post by NedS »

ebo wrote: Tue Nov 10, 2020 7:09 pm For the next ATSC 3.0 HDHR model, or even the current one if it's possible with a firmware change, it would be good to add an option to transcode AC-4 audio to a format that most digital audio players can deal with. AC-3, E-AC-3, even PCM would do.
I don't know if this is possible on a technical level or not, as that would be a question for Nick, but the big hang up here is licensing. It might be a possibility, but it would require an additional cost and convincing Dolby that it was a good idea.

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Re: AC-4 Audio?

Post by signcarver »

Considering how Dolby appeared to be non-responsive to doing something similar on an extend with AC-3, it's most unlikely they would consider such for ac-4 but perhaps that would be an in to get such previous requests on the extend as my understanding it would probably be covered under the same agreement which is how they are pushing tv manufacturers to adding ac-4 for "free" (no additional cost outside the usual licensing)

tvdust
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Re: AC-4 Audio?

Post by tvdust »

NedS wrote: Thu Oct 15, 2020 4:50 pm 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.
I'm not sure what this means. I was thinking of getting a new TV around Black Friday. Should I make sure it decodes AC4? Is there a list yet?

Is AC4 decoding a hardware thing, or can the Roku/Android/whatever smart software on the TV handle it.

I've just started looking into AC4, and it'd drive me crazy to spend $100 ($69 right now) and have to hook up a Roku Ultra player with AC4 encoding to a brand spanking new Roku TV. Is that what I could be looking at? Should I just wait another month?

Crash*N*Burn
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Re: AC-4 Audio?

Post by Crash*N*Burn »

Not sure the best place to post this but, I wanted to try out something, not sure if it means anything.

I have an old (5-6 year old) Zotac ZBOX-MA320 (A4-5000 with Radeon 8330 GPU) 8GB ddr3 1800 RAM and 500GB SSD, and wanted to see if I could get the HEVC channels to display and have audio on this device. I install windows 10 2Hxx on it, installed the SD App from the MS Store and the HEVC codec when I tried to tune to a ATSC 3.0 channel, once installed, I shut down the app, restarted the app, tuned to Channel 11.1 (RDU) and got both video and audio once I installed the HEVC codec.

So, this 5+ yo box was able to properly display and have audio, but the 2015 Nvidia Shield can't without have a Dolby Atmos soundbar?


PS: If I run my TV channels thru Kodi, I can still play the video for HEVC, but there is no sound. So its a limit of the software and the codecs access to other apps on the system and NOT the hardware.

PSS: Using the SD add-on app for Kodi play video but no audio.

kyl416
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Re: AC-4 Audio?

Post by kyl416 »

It's because Nvidia doesn't want to pay for the patent to include native Dolby support on older shields. Until there's an open source AC-4 codec, you won't get audio on it without a soundbar or receiver that can decode AC-4. Kodi, VLC, Emby and Plex all rely on FFmpeg for their media functions, so they don't know what to do with the AC-4 audio stream, it just sees it as an undecodable binary data stream.

There's a bunch of complaints about this on Nvidia's forums, since it also causes issues with Dolby Digital where you miss the first second or two of audio on apps like Netflix, Amazon Prime, Disney+, Vudu, Hulu and HBO Max after playback starts while your soundbar or receiver detects the audio format. If they had native Dolby support they could continue to send AC3 or E-AC3 audio packets so your sound system won't dip out of Dolby mode anytime the audio stops when you do things like pause the video or rewind/fast forward.
Last edited by kyl416 on Tue Nov 24, 2020 2:30 pm, edited 5 times in total.

NedS
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Re: AC-4 Audio?

Post by NedS »

tvdust wrote: Mon Nov 23, 2020 11:36 pm
NedS wrote: Thu Oct 15, 2020 4:50 pm 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.
I'm not sure what this means. I was thinking of getting a new TV around Black Friday. Should I make sure it decodes AC4? Is there a list yet?

Is AC4 decoding a hardware thing, or can the Roku/Android/whatever smart software on the TV handle it.

I've just started looking into AC4, and it'd drive me crazy to spend $100 ($69 right now) and have to hook up a Roku Ultra player with AC4 encoding to a brand spanking new Roku TV. Is that what I could be looking at? Should I just wait another month?
Almost anything could be made to support AC-4 audio with a software update, but the big thing is licensing from Dolby. Most hardware venders won't bother allowing an AC-4 upgrade path (free or paid), because they would rather sell a new model of TV.

LG smart TVs are probably the safest bet if you really want something built-in, but honestly, the best advice for buying TVs is to buy a TV for the display, and not worry about the "smart" part. Sometimes the built-in smart platform is underpowered or using an OS that isn't preferred, but the prices are so low right now that it's significantly cheaper to just buy a decent quality display and then add an external box if needed.

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