AC-4 Audio Support for Android TV

Channels Android TV
#36

ok tried the mecool optical connected direct to sonos soundbar with spidif out enabled on mecool audio options.

with channels surround option enabled or disabled and mecool audio set to auto, the sonos sound is pcm 2.0

with channels surround option enabled or disabled and mecool audio set to passthrough, the sonos sound is pcm 2.0

i still think the reason for this is that channels is giving mecool pcm 2.0 audio, and not ac-4. so mecool never gets the chance to transcode the ac-4 to ac-3.

i do believe that if i was connected to a proper avr, that channels would provide transcoded pcm 6.0. but i believe instead channels should properly query the mecool edid info and pass ac-4 audio to it, and not pcm audio.

#37

We don't support AC-4 passthrough yet. I will need to order one of these devices to do some testing and implement it.

1 Like
#38

thanks for the reply.

just got this from nick at SD:

The HDHomeRun tuner hardware and DVR always passes the original AC4 audio through to the client app.

The Mecool Android device has AC4 to AC3/EAC3/PCM transcode support which the HDHomeRun app supports - the HDHomeRun app invokes AC4-passthrough and the Mecool box converts it to AC3/EAC3/PCM behind the scenes so you get 5.1 surround sound. The cloud transcode service is not involved.

I don't know what the Channels app is doing.

Nick

#39

Correct, we need to passthrough to the OS which is not currently supported by Channels app

1 Like
#40

amazon link

#41

Just got a chance to check my setup. It goes like this, shield tv hdmi - Yamaha avr. - TV.

When surround sound enabled in channels app avr reports 6 channel pcm.

When surround disabled avr reports 2 channel pcm.

On hdhr app with audio pass off. Avr reports 6 channel pcm

On hdhr app with audio pass on avr reports
2 channel Dolby digital

1 Like
#42

wonder why with 'audio pass off' on hdhr it doesn't seem to use their cloud transcode to dolby 5.1?

not that i think their dolby transcode would be better than pcm 6

#43

Sweet - it has LAM too! I need this! :slight_smile:

#44

Me too!! The super rare Lazy Ass Mode :joy:

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#45

I don’t know, I haven’t used that app in over a year. If there is a setting for that im sure I haven’t enabled it. Don’t know much about it.

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#46

hahaha

“Sarcasm is the lowest form of wit, but the highest form of intelligence.”

― Oscar Wilde

1 Like
#47

my take away:

  • channels doesn't support dolby transcoding or ac-4 passthrough (yet)

  • channels does support pcm transcoding. depending on your audio device, you should get either pcm 2 channel or pcm 6 channel audio.

  • the trabscoded pcm volume is unfortunately low. tru turning surround sound option on/off to see it it helps. also make sure one of your other devices isnt transcoding the pcm into another format (i.e. firestick can transcode pcm to dolby with an audio out setting)

IMHO, processing tuner ota broadcasts is channels bread and butter, and should be WAY more on top of supporting the industry nextgen standards. its been a u.s. standard for years now.

#48

Not really accurate.

#49

Completely accurate.
Fact, you will never get 6 channel PCM audio through an optical cable. Even if the cable can technically handle it, any optical port on surround sound hardware does not have the bandwidth to pass it.

Thanks for registering just to post an article that has nothing to do with surround sound.

#50

Sure fiber can handle a huge amount of bandwidth. However it's not a bandwidth issue. The toslink interface (or the way manufacturers implement it) is not compatible with 5.1 surround sound.

#51

I have my Shield (2015) connected to my AVR with HDMI. The AVR shows it getting 5.1 PCM from the Shield when trying to play a channel with AC-4 audio, but there is no sound. DD works fine. Any ideas?

#52

I do not think the Shield natively supports AC4 audio ...

If you specifically want built in AC4 support the current list is:
Roku Ultra 4800X
Roku TVs (modern)
LG TVs 2019+
Fire TV Edition TVs (modern)
Fire TV Cube (3rd gen)
Fire TV Stick 4K (new 2023 model)
Fire TV Stick 4K Max (new 2023 model)
Mecool KM2 Plus
Mi 4K stick (latest)
Many Android phones and tablets.

(also some HiSense and TCL TVs running Android have AC4 support but it is broken).

#53

Thanks, but doesn't Channels support decoding it to PCM in the player? I don't need native support.

#55

We've shipped an Android Beta with expanded support for Audio Passthrough:

#56