AC-4 Audio?

ATSC 3.0 Forum
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CBme
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Re: AC-4 Audio?

Post by CBme »

The 12-29 app update for Nvidia Shield has fixed the crashing when switching from the SAP audio our stations default to, to the 5.1 english audio. For my (non atmos) receiver that shoves the dialog into the left surround channel (on my pc in stereo it shoves in the left site) but the audio-switch crashing and stuttering video seems to have been resolved for this device. Points for progress!
Last edited by CBme on Mon Jan 04, 2021 10:10 pm, edited 1 time in total.

talkenrain
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Re: AC-4 Audio?

Post by talkenrain »

CBme wrote: Wed Dec 30, 2020 3:05 pm The 12-29 app update for Nvidia Sheild has fixed the crashing when switching from the SAP audio our stations default to, to the 5.1 english audio. For my (non atmos) receiver that shoves the dialog into the left surround channel (on my pc in stereo it shoves in the left site) but the audio-switch crashing and stuttering video seems to have been resolved for this device. Points for progress!
Yes, HDHOMERUN 20201229 for Nvidia Shield Pro, addressed the crashing problem (Thank you very much). Audio is still firmly planted in ether the left front channel or the left surround channel (depending on the local channel) using a 7.2.4 atmos system.

mooninite
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Re: AC-4 Audio?

Post by mooninite »

peanutbutter71 wrote: Mon Dec 28, 2020 3:09 pm I compiled this fork of ffmpeg on linux:

https://github.com/richardpl/FFmpeg/tree/ac4

I don't think this is in the main trunk for ffmpeg, but this is at least promising.
That branch is against the main trunk. I compiled a 4.3.x version and Kodi now plays audio for ATSC 3.0 Dallas, TX stations (H.265 + AC-4).

I expect it will take a few months for slower distributions to get ffmpeg 4.4 / 5.0 that will carry this support, but we'll be there much sooner than I guessed.

Alderem
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Re: AC-4 Audio?

Post by Alderem »

Just saw that mentioned on the Plex forums. Fantastic news.

thully
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Re: AC-4 Audio?

Post by thully »

It seems like the Chromecast with Google TV works with AC-4 audio with the latest firmware and HDHomeRun app. I’m using it plugged directly into the TV (no receiver). Audio is a little bit out of sync, though...

ferrellsl
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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Fri May 07, 2021 4:38 pm, edited 3 times in total.

jasonl
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Re: AC-4 Audio?

Post by jasonl »

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Lost Dog
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Re: AC-4 Audio?

Post by Lost Dog »

mooninite wrote: Wed Dec 30, 2020 9:43 pm
That branch is against the main trunk. I compiled a 4.3.x version and Kodi now plays audio for ATSC 3.0 Dallas, TX stations (H.265 + AC-4).

I expect it will take a few months for slower distributions to get ffmpeg 4.4 / 5.0 that will carry this support, but we'll be there much sooner than I guessed.
I compiled the AC-4 branch of ffmpeg and using ffplay I got audio from a ATSC 3.0 stream!!! Woo hoo! This is a start!

How did you get Kodi playing the AC-4? Did you have to compile Kodi against the ffmpeg branch?

kohaiut
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Re: AC-4 Audio?

Post by kohaiut »

ferrellsl wrote: Thu Jan 14, 2021 5:44 pm I completed a successful MSYS2 x64 build of ffmpeg that supports AC-4 audio streams and everything is working great for ATSC3.0/AC4 streams in the greater Phoenix area. For those who want to run the binaries outside of the MSYS2 shell, you will need to copy the following DLL files to the folder where your ffmpeg binaries ultimately reside.
....
I've been watching the ffmpeg feature request 8349 and your comments there. It isn't clear to me what the state is of that request. It seems there's a proof of concept but it isn't clear if what has been done so far is going to be accepted into the next release of ffmpeg or if they devs are going to hold out for more functionality.

What do you think?

airwedge1
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Re: AC-4 Audio?

Post by airwedge1 »

I'm a bit confused by dolby ac-4 / dolby atmos. No receivers or sound bars explicitly say dolby ac-4. But the internet says they are different. Text below.

Will sound bar / receiver need to be upgraded to support ac-4? If the receiver says dolby atmos does that mean it will be able to play dolby ac-4 / atsc 3.0 sound. Will a device like a tv or streaming device transcode the dolby ac-4 to change to a format that the receiver can accept if the receiver does not support natively?

Dolby AC-4 describes the underlying audio technology including the audio compression technology, metadata support and system aspects. Dolby Atmos describes Dolby's immersive audio experience that can be delivered by multiple Dolby audio technologies including Dolby AC-4 and Dolby Digital Plus.

ferrellsl
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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Fri May 07, 2021 4:38 pm, edited 2 times in total.

ebo
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Re: AC-4 Audio?

Post by ebo »

ferrellsl wrote: Thu Jan 14, 2021 5:44 pm For those who don't want to build from source, you can download the Windows binaries from my DropBox account here: https://www.dropbox.com/s/eene7ecard5xk ... 4.zip?dl=0
I tried to download from that link but all I got was a blank page. So I changed ?dl=0 to ?dl=1 and that gave me the download. Was that the right thing to do?

ferrellsl
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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Fri May 07, 2021 4:38 pm, edited 1 time in total.

ferrellsl
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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Fri May 07, 2021 4:38 pm, edited 1 time in total.

Lost Dog
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Re: AC-4 Audio?

Post by Lost Dog »

I was able to compile Kodi 18.9 against the ffmpeg AC-4 branch. Playing ATSC 3.0 stream captures from the PDX market worked well and audio seemed find. I cannot confirm if it was correct channel 5.1 because this was being done on my desktop rather than HTPC (headphone only on my desktop).

Live TV was really buggy however. Many times it froze when trying to tune an ATSC 3.0 station but I suspect that's due to the plugins and not the ffmpeg. When it did manage to tune it seemed to play fine with audio.

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