AC3 Passthrough

Help and support for HDHomeRun DVR and HDHomeRun software for Windows 10, Mac, Android, XBox, etc.
Jedi71
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AC3 Passthrough

Post by Jedi71 »

Connect 4K
Servio
Shield Pro 2019
Chromecast with Google TV

On both of these devices when AC3 Passthrough is on, the sound is SO GOOD! However, it's out of sync. So I have to turn off AC3 Passthrough.

Are there fixes for this being worked on? I'm surprised the hardware can't handle what's coming in on the actual OTA signal. Everything else played through the Shield and Google TV are in sync and on point, Dolby Atmos, etc.

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

what streaming box can deliver Atmos and not be out of sync? Any of them?

NedS
Silicondust
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Re: AC3 Passthrough

Post by NedS »

Is it consistently out of sync, or does the delay drift with time?

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

Connect 4K 10809602
Servio 15303290
LG B7 OLED
Shield Pro 2019
Chromecast with Google TV


With AC3 Passthrough on, it's about half a second out of sync pretty consistently. I've not watched it for long that way, maybe 30 mins total.

Like I mentioned it sounds great, just out of sync. Every channel I tried. I can then exit the HD Homerun App and DD sound is fine through all other apps.

This is running an Nvidia Shield Pro 2019 (and a Chromecast with Google TV) to a LG B7 tv, then out the ARC HDMI to a Sonos Arc sound bar.

I know the streaming devices have the processing power. I'm just trying to find a way to help it.
Thanks!

thedoomster
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Device ID: 131CC070
Location: Rochester, NY

Re: AC3 Passthrough

Post by thedoomster »

Dialog audio is consistently out of sync with video on my SONY Android TVs with AC3 on as well. I don't see this issue on my Chromecast Google TV though. However, there is a big difference in processing power between the two and the SONYs are on version 8 while the Chromecast is on Version 10, in case that might be helpful.

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

AC3 Passthrough still bad on Chromecast with Google TV.

The official FAQ's for AC3 Passthrough sync problems say to disable it. So that's great, but does that mean we aren't meant to get AC3 yet?

Besides a Shield Pro 2019, and Chromecast with Google TV, is there a streamer that processes Dolby from a Connect 4K without sync issues? Apple TV perhaps?

I need to get this straightened out before I can't send this back for a refund. So far this thing isn't anywhere near wife approved, and I'm trying to cancel YouTube TV.

Should I fill out a trouble ticket for each streamer box that has the AC3 sync issue? Thanks!

nickk
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Re: AC3 Passthrough

Post by nickk »

The HDHomeRun app automatically corrects for the AC3 passthrough delay reported by Android.

If you are experiencing a delay you may need to tweak the delay setting in Android Settings.

Nick

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

That would be great, except that Hdhomerun is the only app with a lip sync issue. You Tube doesn't. NETFLIX doesn't, Disney Plus doesn't.

I don't believe you can tweak delays on a per app basis can you?

Does the Apple TV version of the HDHomerun app have this problem?

nickk
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Re: AC3 Passthrough

Post by nickk »

Jedi71 wrote: Tue Jan 19, 2021 5:48 am That would be great, except that Hdhomerun is the only app with a lip sync issue. You Tube doesn't. NETFLIX doesn't, Disney Plus doesn't.

I don't believe you can tweak delays on a per app basis can you?
It sounds like the problem you are experiencing is specific to AC3 passthrough.
Online services don't stream AC3 and don't use AC3 passthrough.

Nick

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

Can a audio delay/tweak be added to the HDHomerun app then? I'm looking for answers so I can determine if I need to return this stuff or not. I really want it to work, but there are too many problems.

nickk
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Re: AC3 Passthrough

Post by nickk »

Jedi71 wrote: Tue Jan 19, 2021 9:34 am Can a audio delay/tweak be added to the HDHomerun app then? I'm looking for answers so I can determine if I need to return this stuff or not. I really want it to work, but there are too many problems.
What device are you running the HDHomeRun app on?

It should have a option in the Android Settings menu to adjust the AC3 passthrough sync. If you adjust it in Android it should then be right for all apps.

Nick

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

Connect 4K 10809602
Servio 15303290
Shield Pro 2019
Chromecast with Google

nickk
Silicondust
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Joined: Tue Jan 13, 2004 9:39 am
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Re: AC3 Passthrough

Post by nickk »

The Shield Pro has a Settings option to adjust the AC3 passthrough delay.

In practice what is is doing is adjusting the delay number that is reported to the HDHomeRun app and the HDHomeRun app corrects for the delay so the audio/video are in sync.

Nick

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

Ok I'll give it shot. I'll see if the Shield Pro can adjust the audio sync of the Dolby Digital output of Hdhomerun while at the same time not ruining the sync of everything else that sounds fine.

However, even if it works, then the problem with channel 5.1 comes back with the Nvidia Shield, with Dallas ch 5.1 showing blocky static on fast scenes, supposedly due to the way Dallas 5.1 encodes their signal.

I guess I'll just have to buy an Apple TV to try it out next.

Jedi71
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Re: AC3 Passthrough

Post by Jedi71 »

Unless there is another option you are talking about, I made adjustments to the Shield Pro audio sync, the one with the bouncing ball.

I got live tv to seem "ok" but then I played a recorded show and the delay was the worst it's been. I even took the Sonos Arc sound bar out of the chain and used the TV speakers. Same issue. I wanted to blame the Arc, but since no other app has ever had a sync issue, I shouldn't have. So there is a difference in audio sync between live tv and recorded tv.

Is there a dev only AC3 sync on the Shield Pro you are referring to?
Thanks!

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