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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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Corry P

Sonos Staff

Hi @kikeminchas, @ste_ms et al

If a factory reset of your LG TV does not help, I can only recommend you get in touch with our technical support team who can, at least, create a case and get things documented - if nothing is documented, there isn’t any evidence that there is a problem and it will therefore not be investigated.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein

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ste_ms

Enthusiast I

@Corry P just checking but if we’ve already been on to support do we already have a case or is there another process to follow?

Also
@RANDUSR23296 has already raised a case as have others possibly, can you confirm if they are being looked at?

You mentioned trying to reproduce the issue in an earlier post and then replied saying it was a CEC issue so presumably you were able to reproduce the problem and so maybe are already in a position to identify a fix or at least confirm it as an LG issue?

Thanks

Corry P

Sonos Staff

Hi @ste_ms

@Corry P just checking but if we’ve already been on to support do we already have a case or is there another process to follow?

If you’ve already been in touch, you will have an existing case. Certainly if you received an email afterwards.

Also
@RANDUSR23296 has already raised a case as have others possibly, can you confirm if they are being looked at?

I can tell you nothing about someone else’s case.

You mentioned trying to reproduce the issue in an earlier post and then replied saying it was a CEC issue so presumably you were able to reproduce the problem and so maybe are already in a position to identify a fix or at least confirm it as an LG issue?

Not really. My colleague spotted something in the logs and recommended a TV reset. That customer refused to reset their TV and stopped replying - nothing came of it. I don’t think we’ve reproduced anything.

Sorry I can’t be of more help.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein

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ste_ms

Enthusiast I

So after an inordinate amount of time and effort trying to solve this I think I might have fixed it with…a new HDMI cable

after trying every variation of settings, resets, earc on/off, and cable testing through the Apple TV (which reported no issue) I tested my PS5 with 5.1 (as reported it defaults to 7.1 in soundbar mode and this worked fine) and did not have the same issue. I then swapped the cables between PS5 and ATV and seemingly no more dropouts on the ATV.

I’m absolutely baffled how the cable can carry Atmos, 7.1 fine but couldn’t do 5.1 - I wonder if a certain pin in the cable is in use that otherwise isn’t with other sound formats?

I need to keep testing as it may come back but for now I wanted to let people know in case I can save them the same frustration I’ve had the last few weeks.

Corry P

Sonos Staff

Hi @ste_ms

Thanks for updating the thread!

That is baffling - as both formats are McLPCM, they both need the additional bandwidth of eARC, so it seems strange indeed that a cable change would permit 5.1 to work when 7.1 already did.

"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein

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kikeminchas

Lyricist III

I tried with different cables also, I am afraid it will come back ;) (hopefully not, in that case, could you let us know the name/model of cable please?) I would understand if you wouldn't want to do it but could you unplug and plug again the soundbard ? I fear the chances of the issue coming back just by doing that are pretty high...

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ste_ms

Enthusiast I

To be clear I changed the cable between my Apple TV and the LG CX, not the cable to the Beam. I used the stock cable supplied with the PS5 and it has continued to work fine last night and today. The original cable was the Belkin high speed one that Apple sell and recommend for ATV4K.

Also the issue never disappeared for me for me after restarting or changing settings etc but disappeared instantly after changing the cable. However I am continuing to monitor it and will update if the issue comes back.

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RANDUSR23296

Enthusiast I

To be clear I changed the cable between my Apple TV and the LG CX, not the cable to the Beam. I used the stock cable supplied with the PS5 and it has continued to work fine last night and today. The original cable was the Belkin high speed one that Apple sell and recommend for ATV4K.

I’m fairly certain that I’ve seen the issue with just a single HDMI device connected (PS5 or Bluray) but that doesn’t mean the action of you changing the ATV cable hasn’t triggered a refresh of some cached HDMI handshake value in the TV - possibly @Fskies saw a similar thing when removing/re-adding the beam from the LG menu.

@ste_ms - Out of interest which HDMI ports do you have assigned to the PS5 and which to the ATV? To date I’ve been assuming they behave the same, but maybe some LG C1s have some buggy ports, I don’t recall if I’ve seen the behaviour on both HDMI1 and HDMI3 (I don’t use HDMI4 yet as it’s wall facing and I now have TV on a slim bracket).

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ste_ms

Enthusiast I

Ps5 - HDMI 1, ATV - HDMI 3. I did try HDMI 4 for the ATV but the dropouts persisted. I also unplugged and replugged to try and trigger a refresh but that didn’t work until I changed the cable.

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RANDUSR23296

Enthusiast I

Ps5 - HDMI 1, ATV - HDMI 3. I did try HDMI 4 for the ATV but the dropouts persisted. I also unplugged and replugged to try and trigger a refresh but that didn’t work until I changed the cable.

I have the dropouts with the sources connected on HDMI3, sometimes an ATV on HDMI1 (makes no difference).

However, quick look on the Internet suggests that HDMI devices don’t seem to be able to detect whether they are interconnected with an Ultra High Speed, Premium, or a regular High Speed cable (I guess that’s why AppleTV has its HDMI cable stability test suite). In any case it appears that the bundled PS5 isn’t labelled Ultra (as I’d assumed it needed to be from the tables I'd seen, but can pass 40Gbps) anyhow so probably wouldn’t trigger any special sort of refresh after all.

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