AC4 Audio And ATSC 3.0

AC4 Audio and ATSC 3.0

There is a new digital TV standard coming.  It is called ATSC 3.0 or NextGen Tv.  ATSC 3.0 uses AC4 audio as its codec.

Most TV markets have at least one ATSC 3.0 channel.  Where I live it is 125.11 PBS, Greenville, NC.  I have a tuner capable of ATSC 3.0 and I supposedly have a TV capable of AC4 audio.  So everything should be hunky dory, right?  Wrong.

No sound.

But John, it says right in the LG specs for this specific TV that it supports AC4 audio.  What gives?

AC4 Audio

TV Specs

Here is what the manual says:

AC4 Audio

Dolby Settings

Kick a Technical Writer In The Balls

Let me say this:  There is a world of FUCKING difference between:

  • Supported Codec: AC4


  • The AC4 codec is only fucking supported when using a wired speaker with Dolby ATMOS support is connected via HDMI ARC and Digital Output is set to “Pass Through”.

The technical writer who wrote, “Supported Codec: AC4” needs a swift kick directly to the balls.  In the event they identify as a woman they need a swift kick to the __________. “insert politically correct genital area terms here”.

Fuck me.

Do you feel me?  You need a sound bar that supports Dolby ATMOS with an HDMI ARC connection and a TV that has an HDMI ARC port.   My TV has the HDMI ARC but my sound bar is ancient.

I bought this TV knowing I would need the AC4 codec one day.   Brand new TV, brand new tuner with ATSC 3.0 and still no sound.

I’m a geek with a Tech Blog and this is happening to me.  How do you think you are going to make out when its time for you to take this leap?

Common Sense

I am only trying to get picture and sound from a TV station that is available over the air and received with an antenna.  Right now I can get the picture, but no sound.   And oh by the way I only get the picture because I have that ATSC 3.0 tuner that I bought.

How does this make any sense?  My TV doesn’t really support AC4.  Not without a wired source capable of decoding it.   Any old HDMI ARC sound bar will NOT work.

As an early adopter of ATSC 3.0 and AC4 audio all I can say is I hope they straighten this out.

4 thoughts on “AC4 Audio And ATSC 3.0

  1. Mike Frisco

    I’d be curious to learn more about the path of data from your HDHR to your TV.

    If you’re using a Plex and its associated apps, you’re out of luck. Plex won’t even let me add ATSC 3.0 stations to my channel lineup. Plex users have been begging for AC-4 decoding for the last three years, while their devs claim they’ve been in licensing negotiations with Dolby for at least *a year and a half*:

    Channels DVR seems to support ATSC 3.0 channels but there are reports of inconsistent audio performance in their forums.

    If you’re using the HDHomeRun app on your TV (which sucks btw) you should get audio. However it does this by uploading your audio stream to Silicon Dust’s cloud service and transcoding AC-4 to AC-3 in real time.

    I feel your pain. This shouldn’t be so hard!

    1. John Hagensieker Post author

      I have an HDHR Flex 4 > LG TV. In order to get this working I had to get a Vizio M213ad-K8
      Sound bar. Even with that I got no audio with HDHR on ATSC 3.0. I connected a 2022 Roku Ultra and using HDHR app finally got me audio on the ATSC 3.0 channel. Not sure if it is cloud decoding or not or if the TV HDMI ARC with new sound bar is doing the trick. Probably have to look at the HDHR logs to see.

  2. Chuck

    I have a Amazon echo studio connected to an new fire cube
    That gets atmos and has a pass through mode , you need to connect it with a special hdmi cable that does audio surround sound ( I forgot the spec) and an input port passed signals through the fire cube . It should pass ac4 audio. From other boxes for atsc3.0. It will all come out in the wash soon I hope. So far its amazing with everything else.

    1. John Hagensieker Post author

      Thanks Chuck. I ended up getting a sound bar that supported AC4. I did all this for a channel I don’t watch in the hopes all the channels head this way soon. Now ATSC 3 is having all kinds of crazy encryption issues in some media markets. Not here thankfully (yet).


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