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.

Corry P 10 months ago

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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Adjunto la información que me da la aplicación Sonos
 

 

Esto es correcto. Si no te haces problemas quedate con esto.

Pues tengo cortes, lamentablemente tengo corte de audio cada minuto es muy molesto así que tendré que pasar Dolby digital de momento..

Si esto es el problema que tratamos de resolver.

Puedes configurar tu ps5 para usar dolby digital o DTS hasta que se arregle. No tengo Xbox pero estoy seguro que es posible también.

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When I’m on my ps5 and audio is playing, I turn on my Apple TV (without switching to its source) and the moment it turns on, the audio cuts, just as it does regularly. It returns moments later.

I can repeat this behaviour, as you say it does sound exactly like the regular audio drops. I pulled the power on the ATV a few seconds after the PCM 5.1 dropped on the active HDMI port. There were 3  short audio drops whilst the ATV booted and then the next scheduled dropped occurred at 59 seconds. I’ll try with the A1 next time I have access to the HDMI ports.

Also, I managed to trap the bug into a single HDMI port. Further to observing the PS5 was bugged and the ATV wasn’t, I then repeatedly swapped the HDMI cables between ports 1 and 3 at the TV end. It didn’t matter which device was playing on port 3, it was the bugged one. HDMI 1 also continued without dropouts, regardless if the source device was PS5 or the apple TV. Suggests the C1 isn’t blameless?

C1 firmware updated to 3.34.70, no change in audio drops. 

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 😬

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When I’m on my ps5 and audio is playing, I turn on my Apple TV (without switching to its source) and the moment it turns on, the audio cuts, just as it does regularly. It returns moments later.

I can repeat this behaviour, as you say it does sound exactly like the regular audio drops. I pulled the power on the ATV a few seconds after the PCM 5.1 dropped on the active HDMI port. There were 3  short audio drops whilst the ATV booted and then the next scheduled dropped occurred at 59 seconds. I’ll try with the A1 next time I have access to the HDMI ports.

Also, I managed to trap the bug into a single HDMI port. Further to observing the PS5 was bugged and the ATV wasn’t, I then repeatedly swapped the HDMI cables between ports 1 and 3 at the TV end. It didn’t matter which device was playing on port 3, it was the bugged one. HDMI 1 also continued without dropouts, regardless if the source device was PS5 or the apple TV. Suggests the C1 isn’t blameless?

C1 firmware updated to 3.34.70, no change in audio drops. 

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 😬

What you’re saying is interesting. For me the ATV is on HDMI 1 and I don’t have sound drops (although it’s usually playing Atmos or stereo content), and the Switch is on HDMI 3 and the PS5 on HDMI 4.

Perhaps it’s HDMI 3 and 4 only which are bugged…

Anyway it’s looking like something with some kind of device polling every 59 seconds.

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Perhaps it’s HDMI 3 and 4 only which are bugged…

Anyway it’s looking like something with some kind of device polling every 59 seconds.

I’ve observed the bug mostly with a single HDMI device connected, which makes me think any polling is coming from the beam2 or C1 itself (hence Quickstart+ setting seemed like a viable lead a few pages back, maybe an LG app interfering in the background).

I’d forgotten about HDMI 4. My C1 is wall mounted since before I noticed the bug. I’d need to re-attach the stand, something for when I have more spare time.

The 1 second dropout might be how an eARC handshake sounds, which could have various triggers - a new EDID appearing upstream, a faulty cable, a buffer overflow...

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Hmm… I did all my previous tests on ports 3 and 4. When the ATV4K arrived, I moved my PC to HDMI1 but had since set it to either Atmos or PCM 7.1. I set it to PCM 5.1 just now and played a 3 minute song uninterrupted.

Whether this is a “workaround” or just a case of the common “randomly works, but mostly bugged”, can’t say yet. As shared before, my ATV4K worked at first and bugged out on the next use but it wasn’t on HDMI1. Maybe if this persists for over a week, I’ll switch over a different device that heavily uses PCM 5.1. 

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When I’m on my ps5 and audio is playing, I turn on my Apple TV (without switching to its source) and the moment it turns on, the audio cuts, just as it does regularly. It returns moments later.

I can repeat this behaviour, as you say it does sound exactly like the regular audio drops. I pulled the power on the ATV a few seconds after the PCM 5.1 dropped on the active HDMI port. There were 3  short audio drops whilst the ATV booted and then the next scheduled dropped occurred at 59 seconds. I’ll try with the A1 next time I have access to the HDMI ports.

Also, I managed to trap the bug into a single HDMI port. Further to observing the PS5 was bugged and the ATV wasn’t, I then repeatedly swapped the HDMI cables between ports 1 and 3 at the TV end. It didn’t matter which device was playing on port 3, it was the bugged one. HDMI 1 also continued without dropouts, regardless if the source device was PS5 or the apple TV. Suggests the C1 isn’t blameless?

C1 firmware updated to 3.34.70, no change in audio drops. 

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 😬

What you’re saying is interesting. For me the ATV is on HDMI 1 and I don’t have sound drops (although it’s usually playing Atmos or stereo content), and the Switch is on HDMI 3 and the PS5 on HDMI 4.

Perhaps it’s HDMI 3 and 4 only which are bugged…

Anyway it’s looking like something with some kind of device polling every 59 seconds.

The problem has always been my ATV on HDMI3, the PS5 on HDMI1 is fine. I had previously moved the ATV to HDMI4 but that never fixed it.

Perhaps the HDMI sockets are split into 2 banks somehow with the Beam being on the HDMI 1 and 2 ‘bank’ due to ARC being HDMI2? Then perhaps it is some kind of interrupt from the 3/4 bank that is causing the issue? I still can’t work out why the Arc would be unaffected though

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Perhaps the HDMI sockets are split into 2 banks somehow with the Beam being on the HDMI 1 and 2 ‘bank’ due to ARC being HDMI2? Then perhaps it is some kind of interrupt from the 3/4 bank that is causing the issue? I still can’t work out why the Arc would be unaffected though

I’m convinced that one of the first things I did when I first noticed the bug was switch between HDMI 1 and 3. At the time though I didn’t consider using two 5.1 devices, just switching between 7.1 and 5.1 on the same device. That was also when the drops were 39 seconds apart. Maybe some LG firmware update shuffled some HDMI chipset contention around to “fix” HDMI 1, at the expense of HDMI 3 getting worse… 

I cannot find much on the internet about the HDMI chipsets, other than the C9 is apparently based on a custom design by Synopsis called Hawk 2. I would expect most smaller devices to use COTS parts, but I guess LG does have the economies of scale to step up to an ASIC/FPGA implementation. 

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When I’m on my ps5 and audio is playing, I turn on my Apple TV (without switching to its source) and the moment it turns on, the audio cuts, just as it does regularly. It returns moments later.

I can repeat this behaviour, as you say it does sound exactly like the regular audio drops. I pulled the power on the ATV a few seconds after the PCM 5.1 dropped on the active HDMI port. There were 3  short audio drops whilst the ATV booted and then the next scheduled dropped occurred at 59 seconds. I’ll try with the A1 next time I have access to the HDMI ports.

Also, I managed to trap the bug into a single HDMI port. Further to observing the PS5 was bugged and the ATV wasn’t, I then repeatedly swapped the HDMI cables between ports 1 and 3 at the TV end. It didn’t matter which device was playing on port 3, it was the bugged one. HDMI 1 also continued without dropouts, regardless if the source device was PS5 or the apple TV. Suggests the C1 isn’t blameless?

C1 firmware updated to 3.34.70, no change in audio drops. 

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 😬

What you’re saying is interesting. For me the ATV is on HDMI 1 and I don’t have sound drops (although it’s usually playing Atmos or stereo content), and the Switch is on HDMI 3 and the PS5 on HDMI 4.

Perhaps it’s HDMI 3 and 4 only which are bugged…

Anyway it’s looking like something with some kind of device polling every 59 seconds.

The problem has always been my ATV on HDMI3, the PS5 on HDMI1 is fine. I had previously moved the ATV to HDMI4 but that never fixed it.

Perhaps the HDMI sockets are split into 2 banks somehow with the Beam being on the HDMI 1 and 2 ‘bank’ due to ARC being HDMI2? Then perhaps it is some kind of interrupt from the 3/4 bank that is causing the issue? I still can’t work out why the Arc would be unaffected though

This is my best guess as well.

It has gotten noticeably worse since the last few updates too.

Adjunto la información que me da la aplicación Sonos
 

 

Esto es correcto. Si no te haces problemas quedate con esto.

Pues tengo cortes, lamentablemente tengo corte de audio cada minuto es muy molesto así que tendré que pasar Dolby digital de momento..

Así es, aquí desde México y con el mismo problema. Lo que impide jugar Nintendo Switch de manera envolvente, ya que Nintendo es tan avara que no paga licencias de Dolby ni de DTS. Y la única manera seria LPCM 5.1 y desgraciadamente, sufrimos de estos cortes tan molestos. Llegaremos a 300 - 500 comentarios y Sonos no resolverá esto? Decepcionante.

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I’m hearing a lot of people talking about updating the TV firmware to the newest version from the Korean website. Is that safe for a European model? And how is it done?

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Just a heads up, an easy way to test this is with a switch. It only outputs 5.1 pcm surround sound (besides stereo & mono) as far as I know. It’ll sometimes work for a week, start dropping out , I’ll tinker, it’ll work again for a limited time. Sometimes only on one HDMI port, makes no sense.

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I wouldn’t have expected it this quickly but todays 15.1.1 update doesn’t fix it

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Dunno why but LG C2 turned on AMD Free Sync . Had no pauses for 5 days. On multichannel pcm 5.1.Just updated to 15.1.1 and now is started again. Am so pissed 😤 

I thought it was just me, so I’m very glad to have found this topic. I also have a Sonos Beam Gen 2, hooked up to an LG C1 and the audio just keeps cutting out when using my Nintendo Switch in surround mode (LPCM 5.1). It’s really a bummer because I would like to get two One’s as surround speakers, but I have decided to hold off on buying new Sonos gear until this issue has been resolved.

I am having this same issue and it has been going on for months. This is specifically woth my switch which can only do pcm 5.1.

 

To further reinforce some other people's notes - this problem only occurs on my switch which is on hdmi 4. Same issue with hdmi 3. But like other people said - hdmi 1 did NOT have this issue when I tried the switch on that. Hdmi 2 is the earc so can't use that one. 

 

What is going on here? I really want to use my surrounds but the constant sound cut off is driving me nuts. My hdmi 1 is for my ps5 and don't want to be limited to one hdmi. This did not always used to happen so it's very frustrating. 

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Same issue here. I have the latest Apple TV 4K (3rd Gen), LG C2 and Sonos Beam Gen 2 (all on the latest software). I get a momentary audio drop every minute or so with ‘Multistream PCM 5.1’ audio only. Every other audio type is fine. I was using my Apple TV on HDMI 4 but changed to HDMI 3 with no improvement. I have good HDMI cables and have swapped them around with no improvement. As suggest above, I’m trying HDMI 1 which seems good (currently testing).

However, as per the linked thread above, it is not the Beam causing this. If you go into one of the hidden menus on the LG by going to Settings > General > Programmes. Then highlight ‘Programme Tuning and Settings’. Then press 11111 (1 five times). Info will be displayed. You will see to 2 ‘more’ links with the second under ‘DVI/HDMI Status’. Click this. In the new info page in the top left you will see it displays the audio format (5.1 is shown as 6CH). Keep this menu displayed when playing 5.1 audio and when an audio drop comes, ‘6CH’ drops to ‘2CH’ momentarily before coming back (I managed to get this on video). Hit the up button on the remote every minute to stop the menu timing out while you do this.

So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source? I also tried an earlier Apple TV 4K box (2nd Gen) and this bizarrely sends 5.1 audio as 7.1 - so I couldn’t use it to test with.

At this point I’m fairly certain it is an issue with the TV. My LG C2 is only 5 days old so I’m considering exchanging it just in case it is a hardware issue, not a software issue. If this was a software issue I’m sure there will be many many posts about this online.

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Keep this menu displayed when playing 5.1 audio and when an audio drop comes, ‘6CH’ drops to ‘2CH’ momentarily before coming back (I managed to get this on video). Hit the up button on the remote every minute to stop the menu timing out while you do this.

Good spot, this is new behaviour.  I’ve recently seen the TV flick between 6ch and 2ch on this menu when I’ve confused it by making too many changes, but it’s the first time I’ve noticed the TV show any reaction at the time of a drop out. In my case it has just flicked between 6ch → 4ch → 6ch during the drop. It didn’t do this when I started looking at this months ago (when I’m certain HDMI 1 was also buggy). Perhaps this indicates LG is looking into this bug after all (or that I just have a bad memory...)

So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source?.

There’s no issue on my alternative eARC devices either (Marantz in my case or Sonos ARC according to this thread), so that logic doesn’t quite stack up. Whilst the Beam 2 may not turn out to be buggy it isn’t blameless in this issue.

Same issue here. I have the latest Apple TV 4K (3rd Gen), LG C2 and Sonos Beam Gen 2 (all on the I also tried an earlier Apple TV 4K box (2nd Gen) and this bizarrely sends 5.1 audio as 7.1 - so I couldn’t use it to test with.

This is confirmed by a few posts on this thread - could be a h/w revision change between gen 1&2 and 3, or just that some manufacturers have no interest I back porting s/w fixes. I’m guessing Beam 3 won’t trigger this issue, will be interesting to see how C3 behaves (if not solved one way or the other by then).

Contributing factors to the bug seem to be:

  • Beam 2 reboots
  • CX-C2 (and G family) TVs
  • HDMI 3 (and 4?)
  • TV cache of HDMI devices (disconnecting the Beam 2 and reconnecting doesn’t clear the bug but fiddling with some of the TV audio/CEC settings can do)
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Can confirm both HDMI 3 and 4 are affected.

And I don’t think it’s up to a specific faulty TV, it’s affecting all of them with this specific setup.

Sure it might be caused by the TV, but since it only affects the beam 2 then Sonos definitely has a hand in it too.

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So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source?.

There’s no issue on my alternative eARC devices either (Marantz in my case or Sonos ARC according to this thread), so that logic doesn’t quite stack up. Whilst the Beam 2 may not turn out to be buggy it isn’t blameless in this issue.

Fair enough. My thinking was that the hidden details state HDMI 3 (or 4) drops to 4CH (correction from above, it drops to 4CH not 2CH, but not every time). The TV is set to pass through audio, so it shouldn’t change the number of channels, but I also guess there is some kind of handshake going on with the Beam that could feed back different source requirements, causing the TV to stumble……? Either way, it sounds like exchanging the TV won’t help and everything now seem to work with Apple TV on HDMI 1. The devices on HDMI 3 and 4 don’t seem to output ‘Multistream PCM 5.1’, so that isn’t an issue.

See video below of the audio drop out and the channel number dropping to 4.

 

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but I also guess there is some kind of handshake going on with the Beam that could feed back different source requirements, causing the TV to stumble……? 

That’s my guess too. eARC has it’s own handshake: the Beam presents the TV with a Capabilities Data Structure (CDS), independently but similar to how the TV presents the AppleTV (and Beam) with an EDID. The CDS received by the TV on HDMI2 would drive the logic in the TV on what audio sink to present to the Apple TV in the EDID on HDMI3.

Without knowing what the audio stream on HDMI3 looks like during the dropout it’s difficult to know if the AppleTV is involved (maybe an HDFury device can “sniff” this) in dropping the audio. Having read a little about the HDMI port implementations it’s also difficult to know which point the 11111 menu is picking to determine the audio format. Is it really what’s in the TMDS stream, or is it examining a transposed stream on an internal I2S link or ARM bus - in which case the Beam 2 may already have had chance to interfere indirectly via the HDMI3 control registers (via a CDS handshake every 59s) whilst the AppleTV keeps streaming Audio/Video happily to HDMI3 as if everything is stable. We do know that the video stream is not interrupted.

I haven’t yet thought of a way to prove/dismiss the above with any of the equipment I have to hand though. Introducing any kind of passthrough sniffer device may even alter the signalling enough to fix the problem enough so that it can’t be observed :(

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Same issue here. I have the latest Apple TV 4K (3rd Gen), LG C2 and Sonos Beam Gen 2 (all on the latest software). I get a momentary audio drop every minute or so with ‘Multistream PCM 5.1’ audio only. Every other audio type is fine. I was using my Apple TV on HDMI 4 but changed to HDMI 3 with no improvement. I have good HDMI cables and have swapped them around with no improvement. As suggest above, I’m trying HDMI 1 which seems good (currently testing).

However, as per the linked thread above, it is not the Beam causing this. If you go into one of the hidden menus on the LG by going to Settings > General > Programmes. Then highlight ‘Programme Tuning and Settings’. Then press 11111 (1 five times). Info will be displayed. You will see to 2 ‘more’ links with the second under ‘DVI/HDMI Status’. Click this. In the new info page in the top left you will see it displays the audio format (5.1 is shown as 6CH). Keep this menu displayed when playing 5.1 audio and when an audio drop comes, ‘6CH’ drops to ‘2CH’ momentarily before coming back (I managed to get this on video). Hit the up button on the remote every minute to stop the menu timing out while you do this.

So it is not the sound bar. It is either the source (although no issue on my other TVs) or the TV. I’m guessing TV as why would it work on HDMI 1 if it was the source? I also tried an earlier Apple TV 4K box (2nd Gen) and this bizarrely sends 5.1 audio as 7.1 - so I couldn’t use it to test with.

At this point I’m fairly certain it is an issue with the TV. My LG C2 is only 5 days old so I’m considering exchanging it just in case it is a hardware issue, not a software issue. If this was a software issue I’m sure there will be many many posts about this online.

I’m sure I checked the HDMI status to see if it changed during the dropouts but didn’t see it previously - possibly a tweak in the firmware since then? The app never shows a change from PCM 5.1 when it drops out that I’ve seen.

If it was TV only then why would the Arc be unaffected? Regardless it feels that we’re homing in on the issue here 

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I have contacted LG UK (since I just assumed the local LG Israel here will be completely useless in addressing the matter) and after a good 4 days they responded to my email. I will update if I come up with anything useful.

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If the audio is actually dropping at the source (AppleTV, PS5, etc) then maybe streaming PCM 5.1 out of a Linux device may yield some debug info in the system logs. May plug a raspberry pi into HDMI 3 when I have a couple of hours to experiment.

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Regardless it feels that we’re homing in on the issue here 

Also encouraging that recently more unique posters are finding this thread and describing similar experiences

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I’m sure I checked the HDMI status to see if it changed during the dropouts but didn’t see it previously - possibly a tweak in the firmware since then? The app never shows a change from PCM 5.1 when it drops out that I’ve seen.

Sometimes it didn’t do it. It was about 1 in 3 change of showing. In the app, when you start playing something it takes a second or so for the app to show the format. I’m guessing the dropout is so quick that the app doesn’t have time to react.

Update on HDMI 1 - I’ve watched my Apple TV 4K Gen 3 for maybe 6 hours and it seems good so far.

Also - my previous TV was a LG SM9000 which also has eARC. I had no issues with this at all running the same Apple TV 4K Gen 3 and the Beam Gen 2.

I contacted Sonos support so they know there is another user with the same issue.

 

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