Trending Lyricist I

Multichannel PCM 5.1 dropping out since 14.10 update

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Anyone else experiencing the same issue? Multichannel PCM 5.1 blanks out for a second every 1-2 minutes. I don’t think it’s a bandwidth issue as it works flawlessly with Multichannel PCM 7.1 (thorough test) and Dolby TrueHD Atmos (quick test). And it may have been caused by the Sonos 14.10 update. Setup is PS5→ LG C1→ Beam 2 (via earc).

2 weeks ago before the 14.10 update, I watched a bluray film wherein I had my PS5 transcode the DTS-HD MA 5.1 audio to Multichannel PCM 5.1 (as the C1 does not support DTS) and had no issues. Earlier today, I played a bluray film for the first time in 2 weeks and I encountered consistent audio dropouts every 1-2 minutes. It had the same setup where DTS-HD MA 5.1 → Multichannel PCM 5.1. I tested other bluray discs including the one I watched 2 weeks ago and they all now have the same issue.

Curiously, I’ve been gaming heavily on my PS5 the past two 2 weeks and haven’t had any audio issues. Then I realized that I’ve been using Multichannel PCM 7.1 when gaming on my PS5. So I made some changes under the PS5 sound settings to make it output Multichannel PCM 5.1 instead. Lo and behold, I am now getting the same consistent dropouts in games and even on the PS5 main menu.

I think it’s due to the Sonos 14.10 update as that’s the only firmware update I’ve done in the last 2 weeks. No PS5 update, no LG C1 update. Well actually while I was composing this post, I received and applied the latest LG C1 firmware update and I still have the same issue.

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Pinned Reply By Corry P

Hi @throwawaybeam2 et al

We now recommend you reach out to the TV manufacturer (LG) as this behaviour is also occurring with different soundbar manufacturers (so it’s not a Sonos-specific issue).

Alternatively, please utilize different audio formats from McLPCM 5.1 (e.g., McLPCM 7.1, DD+, etc).

I hope this helps.

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OmriP

Lyricist III

It almost seems to infer that the LG Technical Team are aware of a hardware issue with that TV model. I would have the repair and just see what happens after that.

No don’t try to pawn off the issue to LG lol. It’s a Sonos issue as well, clearly.

To be fair, I did think of a scenario where the Beam 2 is blameless: Maybe the TV has a bug that means the first device eARC device it registers (and it does seem to cache the details of eARC devices) is bugged, but subsequent devices are not (it’s not uncommon for first items in software containers to trigger additional logic or follow modified algorithms that subsequent items added do not).

That would give the illusion to a Beam2 owner that it somehow was triggering the problem yet in reality it was still functioning 100% to spec, particularly as eARC devices are still relatively rare and the Beam2 was likely the first eARC device connected up. Testing a different eARC device (for the fewer users who have access) would work fine and look like only the Beam2 was bugged.

However, if this was the case here, I’d expect to see reports on internet about other devices having dropouts, because they’re the first plugged in, but I couldn’t find any. I could (probably) test this by factory reseting the TV and connecting my AVR as the first eARC, but the lack of evidence on my searches suggests this would not be worth the effort.

Also, that doesn’t prevent Sonos support actively help isolate the issue, and/or even giving some sensible technical engagement (I do appreciate @Corry P’s recent update indicating related activity by the community team).

If this were the case you’d see loads of posts here about people with Sonos Arc, or any other soundbar. The fact that it’s so specific to the beam 2 suggests it isn’t blameless.

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RANDUSR23296

Enthusiast I

I also sacrificed a “high speed with ethernet” HDMI cable and cut what I think is pin 13 (CEC), but whilst the HDMI 2 video is intact, and I’m now able to de-activate CEC (the remote also stays working), the TV doesn’t engage either eARC or ARC and audio is limited to the TV speaker. I cut the red wire - maybe I should have cut blue 😬

I found some of these HDMI breakouts and buzzed out my sacrificial HDMI cable and I did manage to cut (only) pin 13 successfully. Not sure why C1/Beam 2 eARC is so dependent on CEC, it shouldn’t need to be.

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RANDUSR23296

Enthusiast I

Apple TV 4K 2nd Gen and later support eARC so could be used for testing. I may give this a go if I get a chance later today (my HDMI ports are a real pain to access though).

https://support.apple.com/en-gb/HT207117

I had chance to try that with a HomePod mini - I couldn’t find a way to get it out of PCM 2.0, but admittedly didn’t spend long trying to work out why.

Interesting. What were you using as the source? I was thinking of trying my ATV 4K Gen 2 as eARC and putting my Gen 3 on HDMI 3 or 4, after re-setting the TV.

In this caseI used PS5 (playing Steven Wilson blurays (remixes and solo albums) - they typically have a choice of PCM 2.0, 5.1, DTS and sometimes ATMOS and the prog rock albums tend to have fewer gaps between songs).

I found Elton John’s Farewell From The Dodger Stadium on Disney+ a useful LPCM 5.1 test on AppleTV. It’s live, >2hrs with no silences, and I’m used to hearing those songs over the years so they don’t wind me up. I can then flick to something like Hamilton for a bitstream/Atmos test.

I will have another go sometime this week using the Raspberry Pi, as that’s actually now the simplest source to flick between formats (now that it’s setup) even if the audio is a little dull...

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MJW75

Enthusiast I

Update. I’ve had no issues with my Apple TV 4K Gen3 on HDMI 1. But the issue still bugs me because I know the issue is there and could cause issues in the future (i.e. when my son wants to play his Switch on the TV or we buy a PS5). I put my Apple TV back on HDMI 3 and the issue returned instantly, as expected. But, I then swapped the HDMI cable between the TV HDMI 2 (eARC) and the Beam Gen2.

The cable I used is a one way fiberoptic cable. I thought maybe the one way nature might stop whatever the Beam is sending to the TV and interrupting it every 59 seconds….. anyway, I’ve tested for about 1 hour now and it hasn’t had a single dropout. I know this isn’t long, but it instantly started dropping out with the original Sonos supplied cable. I’ll keep it setup like this and will report back when I’ve tested it some more.

M

MJW75

Enthusiast I

Update - 5 hours of watch time on a 5.1 PCM source (my wife is bingeing Star Wars Rebels on Disney+). Not a single dropout so far.

To clarify my previous post, the cable I used is a HDMI 2.1 one way optical cable.

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OmriP

Lyricist III

Update - 5 hours of watch time on a 5.1 PCM source (my wife is bingeing Star Wars Rebels on Disney+). Not a single dropout so far.

To clarify my previous post, the cable I used is a HDMI 2.1 one way optical cable.

Does it stay like this on hdmi 3 / 4 after power cycling?
What happens if you change back the cable? And then back again?

I doubt it’s the cable because I’ve tried multiple cables and all had these problems.

M

MJW75

Enthusiast I

Does it stay like this on hdmi 3 / 4 after power cycling?
What happens if you change back the cable? And then back again?

I doubt it’s the cable because I’ve tried multiple cables and all had these problems.

Did you try a one way optical HDMI cable?

Leaving the optical HDMI cable installed and the Apple TV on HDMI 3, I power cycled everything. Tested for 30 mins (I know that isn’t long), but no issues. I power cycled everything again leaving everything off for 10 mins. It still worked when it powered back on.

I then power cycled again and changed to the original supplied Sonos HDMI cable between the TV and Beam Gen 2. The issue came back straight away. Power cycled again and the issue is still there.

I just put the optical cable back in and it seems to work again.

I’ll concede that it could be something else, but what I can say is that in my testing it consistently doesn’t work with the regular HDMI cable and consistently does work with the optical HDMI cable. I’ll keep the optical cable plugged in and the Apple TV on HDMI 3 and will update here in a few more days.

If anyone with this issue has a one way optical HDMI cable, please can you try and replicate my findings. Alternatively, they can be bought relatively cheaply on Amazon.

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RANDUSR23296

Enthusiast I

No change with my Kabeldirekt 5m optical on HDMI 3, didn’t need to power cycle the beam. My understanding is whilst the TMDS signal is converted actively to optical, the ARC/eARC signals are still copper wires (at least on the shorter runs). Maybe some optical cables do more than just pass through and/or have optical returns.

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MJW75

Enthusiast I

No change with my Kabeldirekt 5m optical on HDMI 3, didn’t need to power cycle the beam. My understanding is whilst the TMDS signal is converted actively to optical, the ARC/eARC signals are still copper wires (at least on the shorter runs). Maybe some optical cables do more than just pass through and/or have optical returns.

I read somewhere that some features are still bi-directional on optical HDMI but thought I’d try it anyway. I can’t explain why it is working for me and not you. Just to check - you put the cable between the TV and Beam right, with the TV at the source end of the cable? Not between the source and the TV.

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RANDUSR23296

Enthusiast I

I read somewhere that some features are still bi-directional on optical HDMI but thought I’d try it anyway. I can’t explain why it is working for me and not you. Just to check - you put the cable between the TV and Beam right, with the TV at the source end of the cable? Not between the source and the TV.

I had the source end of the optical cable on the beam, other end in TV HDMI2. So I swapped the ends over (source in TV HDMI2 other into the Beam) and so there was no Sonos video displayed on HDMI2 (as now the cable is in reverse) however eARC was functioning and the dropouts ceased.

...Until I rebooted the beam and there were mini dropouts every 5 seconds. Pulling the optical cable out the beam didn’t clear them, but rebooting the TV did, and the 59s drops didn’t return either.

Reverting eARC to the Sonos provided HDMI cable also reverted the 59s dropouts

I wonder what the minimum set of connected pins is required to make eARC work but not necessarily any other HDMI feature. What might the embedded optical cable transceiver chipsets be telling the TV and/or Sonos when connected in reverse?

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