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Prodan
Avid Contributor I
November 3, 2017

If you're experiencing audio delay issues, read this

I've been living with lip sync issues (audio behind the video) since I got my Playbar about a year ago but I finally decided to do something about it. After multiple conversations with Sonos support and the LG's support people (they kept blaming each other for the audio delay), I decided to email Sonos' CEO about the issue.

After a few hours, I got a reply back from him, CCing a team manager who was going to look into the issue. We scheduled a call and he had me send various diagnostics to him. He said that the engineering team was going to investigate and get back to me.

A week later, I got an update. He told that they are still working on the issue. He also said that only one other person had reported the same issue (I assume that means that only one other person with an LG TV). So, if you're having audio delay issues and you've tried all other troubleshooting, reach out to Sonos support and have them look into it. If it helps you might mention my reference number, which has already been escalated:

Keep in mind that my setup is pretty straight forward (LG C6 OLED TV connected directly to the Playbar via Optical, audio playing from the built-in apps) and every single thing LG and Sonos suggested, including going into the TV's service menu and changing things there.

I know there are multiple post on the topic so hopefully we can solve at least some of the issues causing audio delay.

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    ronaldianho
    Lyricist III
    January 8, 2021

    I've been living with lip sync issues (audio behind the video) since I got my Playbar about a year ago but I finally decided to do something about it. After multiple conversations with Sonos support and the LG's support people (they kept blaming each other for the audio delay), I decided to email Sonos' CEO about the issue.

    After a few hours, I got a reply back from him, CCing a team manager who was going to look into the issue. We scheduled a call and he had me send various diagnostics to him. He said that the engineering team was going to investigate and get back to me.

    A week later, I got an update. He told that they are still working on the issue. He also said that only one other person had reported the same issue (I assume that means that only one other person with an LG TV). So, if you're having audio delay issues and you've tried all other troubleshooting, reach out to Sonos support and have them look into it. If it helps you might mention my reference number, which has already been escalated:

    Keep in mind that my setup is pretty straight forward (LG C6 OLED TV connected directly to the Playbar via Optical, audio playing from the built-in apps) and every single thing LG and Sonos suggested, including going into the TV's service menu and changing things there.

    I know there are multiple post on the topic so hopefully we can solve at least some of the issues causing audio delay.

    Incredible to me that 3 YEARS LATER this is still an issue. What’s the deal, Sonos?!

    My situation… I have an LG 55C7P OLED TV. I have three peripheral devices connected to it via the C7’s HDMI inputs -- a DirecTV box, 4K AppleTV and a 4K Blu-Ray player. 

    My Sonos Arc Soundbar (along with Sonos Subwoofer and two Sonos Ones as rears) is connected using the HDMI-ARC port on my TV. I continue to have major audio sync issues with all three peripheral devices when they’re playing content with Dolby Digital or Dolby Atmos audio. There are no sync issues when I use the LG TV’s internal apps. The only way I can get rid of the sync issues is by switching the peripheral devices to PCM, but that, of course, defeats the purpose of having this INCREDIBLY EXPENSIVE SOUND SYSTEM I BOUGHT THAT DOESN’T WORK WITH A TOP LINE TV!

    I may try the HD Fury Arcana, although they tell me I need to also purchase one of their 4K HDMI switchers, which isn’t an ideal solution because, 1) it means I can’t adjust the video for each device since they’ll all be going into the same input on the TV, and 2) between the Arcana and the HDMI switcher we’re talking another $600!!!

    So, two questions for SONOS, or for anyone here who might be able to help me solve this.

    1. Is Sonos planning on FINALLY, at long last, providing some sort of firmware update to the Sonos Arc soundbar (and their other soundbars) to fix this audio sync issue? I’m assuming the answer is no, but hey, I’d love to be wrong.
    2. Short of that, I’m considering upgrading my TV to a 65”. What TV’s, preferably an OLED type, work best with the Sonos sound system. I.E., they have ZERO audio sync issues? Can Sonos provide a LIST of TV’s that work best with the Arc Soundbar? Or, how about a list of TV’s that DON’T work with the Arc Soundbar? That feels like a reasonable request. (A Sonos rep I spoke to told me, on the sly, that the new Samsungs do not have issues. But then I read about all kinds of Samsungs that do. Has that changed?)

    Thanks so much in advance for any help and thoughts on what I should do next. -- Ian

    Believe it or not, this is actually an hdmi ARC protocol issue. The ARC standard does not mandate lip syncing and thus is not widely supported, or if it is, it's implemented differently among manufacturers. When you want to pass surround sound via Hdmi ARC, it must be done via bitstream (compressed audio such as 5.1 dolby digital) since arc does not support pcm uncompressed 5.1 (it is sent as two-channel stereo instead due to arc bandwidth limitations and other reasons I may be unaware of).

     

    So if you want any audio delay issues to be 99% of the time fixed while utilizing Hdmi ARC / passthrough, you must send it as PCM two-channel audio. This is the downside of Hdmi ARC...it can introduce audio delays since when your TV has processed both the video and audio, it sends the compressed dolby digital or dts (both bitstream) to the audio receiver / sound bar and does not know how long that receiver or Soundbar will take to process that audio. Therefore, it is not uncommon for the audio to actually come after the video.

    Unfortunately, most TVs are not able to delay the video to sync up with the delayed audio except for some very modern tvs (I believe samsung has a couple models that do this... They can delay both audio or video...so an audio delay and negative delay to match the video coming before the audio).

    I am not sure why all TVs are able to delay audio but not the video since HDMI ARC has this common issue and nobody wants to output PCM uncompressed audio to their Soundbar receiver as it can only be passed through as two channel audio. It solves the issue of audio delay since the TV knows when it has processed each of the video and audio and can send both out at the same time and the receiver or sound bar simply has to then play the audio, rather than decompressing it from Dolby digital to output to its speakers as the directly playable pcm. 

    To add to my earlier comment here and a mini guide on audio formats that is easier to understand (hopefully) than browsing websites and various forums to save people days on end:

     

    1. eARC solves these issues. Lip syncing / AV sync is mandated for this standard.

     

    2. If you did somehow have delay issues (unlikely), even with this mandated lip syncing support among all eARC devices, you could correct this by sending PCM on as uncompressed 5.1 or 7.1 audio over the eARC standard as it has higher bandwidth and can support all uncompressed audio formats and even lossless formats such as True HD decompressed and sent as PCM afaik. 

     

    So basically, eARC will allow all of us to send whatever kind of audio we want and still maintain our source channels, whether it be 5.1, 7.1, etc, due to higher standards and bandwidth. I am unknowledgeable on this however as it relates to higher channel inputs/outputs above 7 channel though. No longer will it matter what settings we want to use as the input/output (with my exception above regarding my lack of knowledgeable above 7 channel) as on the other side it should always work in theory. 

     

    For people who aren't able to follow due to having a hard time understanding this...as it currently stands:

     

    PCM means you are taking your compressed Dolby Digital or DTS format and decompressing it ("larger size" now) to send over a cable (HDMI ARC or optical) to your output device (sound bar, audio receiver, surround, etc.) at that larger size of data. Since the TV is processing both the video and audio, it knows how to time both of these and audio sync delays delays are not likely.

    Bitstream means you are simply sending your compressed Dolby Digital or DTS format and sending it through to your output device (sound bar, audio receiver, surround, etc.) over HDMI ARC or optical. This supports more outputs and formats without 5.1 being converted to 2.1 since more cables can handle data that is compressed / "a smaller size". It is the surround receiver / sound bar that then converts this compressed audio, which is why we may have an audio delay on our tvs since the TV does not know how long this other device will take to process the audio (unless that device shares how long it is taking to process the audio, as is mandated by the eARC protocol).

     

    Optical and ARC:

    - Supports stereo

    - Supports "compressed"  dolby digital 5.1 (aka bitstream option - i.e. sending the compressed signal as is)

    - Supports "compressed" dolby digital plus and DTS 5.1 (aka bitstream option - i.e. sending the compressed signal as is)

    - If you have a dolby digital or DTS 5.1 source and you choose to output as PCM over optical or ARC, it will output as stereo since the cable / standard doesn't support a PCM (i.e. uncompressed) signal due to bandwidth and limitations of the standard) - this PCM option however will resolve lip sync issues since the TV is sending the audio to the surround receiver/sound bar all "ready to go and play" as it's already been processed by the TV and that surround receiver / sound bar simply has to play the signal (assuming you haven't used any crazy effects that add on to that output) without doing anything to it. 

     

    eARC:

    - Supports pretty much everything necessary today

     

    Just don't get confused with compressed and uncompressed with lossy and lossless. Two different things. Compressed audio is simply like a zip file on a computer. All of the data is still in that folder, just a smaller compressed size. The zip file would be like a dolby digital or dts format. Uncompressed audio would be one of those zip files (dolby digital or dts) being extracted into their actual audio files (PCM), which are actually directly usable by the computer or in this case, the audio output device, whether it be a sound bar or surround receiver. Lossy audio files (dolby digital, dolby digital plus, dts) are like jpg images. Lossless audio files are like Tiff, raw, dng, png images (Dolby True HD, DTS-HD). An exception is Dolby Atmos, which is more of a channel type / extension that allows for height and spatial sound that doesn't rely on traditional channels.

     

    Hope this helps all novices since it took me awhile to grasp everything!

    So eARC would solve my lip sync issues? I would consider returning my Philips TV for a model with eARC if it solves my issues.

    Bulletbling
    Lyricist III
    January 8, 2021

    I've been living with lip sync issues (audio behind the video) since I got my Playbar about a year ago but I finally decided to do something about it. After multiple conversations with Sonos support and the LG's support people (they kept blaming each other for the audio delay), I decided to email Sonos' CEO about the issue.

    After a few hours, I got a reply back from him, CCing a team manager who was going to look into the issue. We scheduled a call and he had me send various diagnostics to him. He said that the engineering team was going to investigate and get back to me.

    A week later, I got an update. He told that they are still working on the issue. He also said that only one other person had reported the same issue (I assume that means that only one other person with an LG TV). So, if you're having audio delay issues and you've tried all other troubleshooting, reach out to Sonos support and have them look into it. If it helps you might mention my reference number, which has already been escalated:

    Keep in mind that my setup is pretty straight forward (LG C6 OLED TV connected directly to the Playbar via Optical, audio playing from the built-in apps) and every single thing LG and Sonos suggested, including going into the TV's service menu and changing things there.

    I know there are multiple post on the topic so hopefully we can solve at least some of the issues causing audio delay.

    Incredible to me that 3 YEARS LATER this is still an issue. What’s the deal, Sonos?!

    My situation… I have an LG 55C7P OLED TV. I have three peripheral devices connected to it via the C7’s HDMI inputs -- a DirecTV box, 4K AppleTV and a 4K Blu-Ray player. 

    My Sonos Arc Soundbar (along with Sonos Subwoofer and two Sonos Ones as rears) is connected using the HDMI-ARC port on my TV. I continue to have major audio sync issues with all three peripheral devices when they’re playing content with Dolby Digital or Dolby Atmos audio. There are no sync issues when I use the LG TV’s internal apps. The only way I can get rid of the sync issues is by switching the peripheral devices to PCM, but that, of course, defeats the purpose of having this INCREDIBLY EXPENSIVE SOUND SYSTEM I BOUGHT THAT DOESN’T WORK WITH A TOP LINE TV!

    I may try the HD Fury Arcana, although they tell me I need to also purchase one of their 4K HDMI switchers, which isn’t an ideal solution because, 1) it means I can’t adjust the video for each device since they’ll all be going into the same input on the TV, and 2) between the Arcana and the HDMI switcher we’re talking another $600!!!

    So, two questions for SONOS, or for anyone here who might be able to help me solve this.

    1. Is Sonos planning on FINALLY, at long last, providing some sort of firmware update to the Sonos Arc soundbar (and their other soundbars) to fix this audio sync issue? I’m assuming the answer is no, but hey, I’d love to be wrong.
    2. Short of that, I’m considering upgrading my TV to a 65”. What TV’s, preferably an OLED type, work best with the Sonos sound system. I.E., they have ZERO audio sync issues? Can Sonos provide a LIST of TV’s that work best with the Arc Soundbar? Or, how about a list of TV’s that DON’T work with the Arc Soundbar? That feels like a reasonable request. (A Sonos rep I spoke to told me, on the sly, that the new Samsungs do not have issues. But then I read about all kinds of Samsungs that do. Has that changed?)

    Thanks so much in advance for any help and thoughts on what I should do next. -- Ian

    Believe it or not, this is actually an hdmi ARC protocol issue. The ARC standard does not mandate lip syncing and thus is not widely supported, or if it is, it's implemented differently among manufacturers. When you want to pass surround sound via Hdmi ARC, it must be done via bitstream (compressed audio such as 5.1 dolby digital) since arc does not support pcm uncompressed 5.1 (it is sent as two-channel stereo instead due to arc bandwidth limitations and other reasons I may be unaware of).

     

    So if you want any audio delay issues to be 99% of the time fixed while utilizing Hdmi ARC / passthrough, you must send it as PCM two-channel audio. This is the downside of Hdmi ARC...it can introduce audio delays since when your TV has processed both the video and audio, it sends the compressed dolby digital or dts (both bitstream) to the audio receiver / sound bar and does not know how long that receiver or Soundbar will take to process that audio. Therefore, it is not uncommon for the audio to actually come after the video.

    Unfortunately, most TVs are not able to delay the video to sync up with the delayed audio except for some very modern tvs (I believe samsung has a couple models that do this... They can delay both audio or video...so an audio delay and negative delay to match the video coming before the audio).

    I am not sure why all TVs are able to delay audio but not the video since HDMI ARC has this common issue and nobody wants to output PCM uncompressed audio to their Soundbar receiver as it can only be passed through as two channel audio. It solves the issue of audio delay since the TV knows when it has processed each of the video and audio and can send both out at the same time and the receiver or sound bar simply has to then play the audio, rather than decompressing it from Dolby digital to output to its speakers as the directly playable pcm. 

    To add to my earlier comment here and a mini guide on audio formats that is easier to understand (hopefully) than browsing websites and various forums to save people days on end:

     

    1. eARC solves these issues. Lip syncing / AV sync is mandated for this standard.

     

    2. If you did somehow have delay issues (unlikely), even with this mandated lip syncing support among all eARC devices, you could correct this by sending PCM on as uncompressed 5.1 or 7.1 audio over the eARC standard as it has higher bandwidth and can support all uncompressed audio formats and even lossless formats such as True HD decompressed and sent as PCM afaik. 

     

    So basically, eARC will allow all of us to send whatever kind of audio we want and still maintain our source channels, whether it be 5.1, 7.1, etc, due to higher standards and bandwidth. I am unknowledgeable on this however as it relates to higher channel inputs/outputs above 7 channel though. No longer will it matter what settings we want to use as the input/output (with my exception above regarding my lack of knowledgeable above 7 channel) as on the other side it should always work in theory. 

     

    For people who aren't able to follow due to having a hard time understanding this...as it currently stands:

     

    PCM means you are taking your compressed Dolby Digital or DTS format and decompressing it ("larger size" now) to send over a cable (HDMI ARC or optical) to your output device (sound bar, audio receiver, surround, etc.) at that larger size of data. Since the TV is processing both the video and audio, it knows how to time both of these and audio sync delays delays are not likely.

    Bitstream means you are simply sending your compressed Dolby Digital or DTS format and sending it through to your output device (sound bar, audio receiver, surround, etc.) over HDMI ARC or optical. This supports more outputs and formats without 5.1 being converted to 2.1 since more cables can handle data that is compressed / "a smaller size". It is the surround receiver / sound bar that then converts this compressed audio, which is why we may have an audio delay on our tvs since the TV does not know how long this other device will take to process the audio (unless that device shares how long it is taking to process the audio, as is mandated by the eARC protocol).

     

    Optical and ARC:

    - Supports stereo

    - Supports "compressed"  dolby digital 5.1 (aka bitstream option - i.e. sending the compressed signal as is)

    - Supports "compressed" dolby digital plus and DTS 5.1 (aka bitstream option - i.e. sending the compressed signal as is)

    - If you have a dolby digital or DTS 5.1 source and you choose to output as PCM over optical or ARC, it will output as stereo since the cable / standard doesn't support a PCM (i.e. uncompressed) signal due to bandwidth and limitations of the standard) - this PCM option however will resolve lip sync issues since the TV is sending the audio to the surround receiver/sound bar all "ready to go and play" as it's already been processed by the TV and that surround receiver / sound bar simply has to play the signal (assuming you haven't used any crazy effects that add on to that output) without doing anything to it. 

     

    eARC:

    - Supports pretty much everything necessary today

     

    Just don't get confused with compressed and uncompressed with lossy and lossless. Two different things. Compressed audio is simply like a zip file on a computer. All of the data is still in that folder, just a smaller compressed size. The zip file would be like a dolby digital or dts format. Uncompressed audio would be one of those zip files (dolby digital or dts) being extracted into their actual audio files (PCM), which are actually directly usable by the computer or in this case, the audio output device, whether it be a sound bar or surround receiver. Lossy audio files (dolby digital, dolby digital plus, dts) are like jpg images. Lossless audio files are like Tiff, raw, dng, png images (Dolby True HD, DTS-HD). An exception is Dolby Atmos, which is more of a channel type / extension that allows for height and spatial sound that doesn't rely on traditional channels.

     

    Hope this helps all novices since it took me awhile to grasp everything!

    So eARC would solve my lip sync issues? I would consider returning my Philips TV for a model with eARC if it solves my issues.

    That's the idea of mandatory lip sync correction in eARC so it SHOULD, but I have not used it yet and technology is never perfect. Maybe others will chime in or you can find some videos about it. 

    Austiopath
    Contributor I
    January 20, 2021

    Please add me to the list here of disappointed Sonos Arc owners. 

    I just recently purchased a Sonos Arc for my 2017 LG B7 OLED, which is Atmos and ARC compatible. 

    I have a brand new Chromecast with Google TV and an XBOX One X (both Atmos compatible) hooked up to the TV, then running audio to the Sonos Arc via the HDMI ARC out (not eARC). All devices and TV set to bitstream (non-PCM). 

    When I use my LG TV’s internal streaming apps, audio/video sync is perfect, including Atmos content on Netflix, Vudu etc. Verified via Sonos app that it is receiving full Atmos signal. 

    When I try to listen to Dolby content coming from my external devices, the audio is noticeably behind the video.

    • Dolby Atmos content from the Chromecast or Xbox works but there is significant delay to the point of unwatchability
    • Non-Atmos Dolby 5.1 content from Chromecast or Xbox is a little bit delayed… noticeable if you’re looking for it.
    • PCM audio from Chromecast or Xbox has no sync issues. 

    I’ve messed with all the various audio settings in my TV to make sure any sort of additional processing is removed. I’ve also tried playing with the delay, because LG does offer the option to move sound earlier, but moving it as early as it goes (-5 in the settings) doesn’t fix it enough on Atmos (also it’s not a great fix given that the TV is applying this negative delay to all content on a given input uniformly regardless of audio format. 

    I’m totally at a loss on what to do. Buying some third party audio splitter like the Sharc makes the elegance of the Sonos a moot point. And this seems like a pretty systemic issue with many popular TV manufacturers. Even with all the various Sonos and Reddit forum posts, plus this Guardian article (https://www.theguardian.com/money/2020/sep/06/that-syncing-feeling-when-your-soundbar-lets-you-down), I’m surprised more people aren't complaining, because I don't think my TV/component combo is any sort of “edge case”… it’s pretty common. Are most people just using their TV’s streaming apps exclusively for Atmos content and therefore not seeing the delay?

    From what I understand, even if I upgraded to a new TV like the LG CX that has HDMI 2.1 and eARC, this lip sync would still be a problem because neither Xbox One X nor any streaming box is HDMI 2.1 compatible so it couldn’t utilize more advance synchronization on those devices. 

    Where’s the list of popular high quality HDTVs that have been verified as not having this issue with external devices running Atmos?

    I really love the look and the sound and the simplicity of the Sonos Arc, and I don't want to return it, but I may be forced to exchange it for a soundbar that doesn’t rely on ARC and just does a more standard receiver-style HDMI passthrough to avoid these audio delays. 

    Does anyone have any other suggestions before I throw in the towel?

    Thanks!
    Ben 

     

    Bulletbling
    Lyricist III
    January 20, 2021

    Please add me to the list here of disappointed Sonos Arc owners. 

    I just recently purchased a Sonos Arc for my 2017 LG B7 OLED, which is Atmos and ARC compatible. 

    I have a brand new Chromecast with Google TV and an XBOX One X (both Atmos compatible) hooked up to the TV, then running audio to the Sonos Arc via the HDMI ARC out (not eARC). All devices and TV set to bitstream (non-PCM). 

    When I use my LG TV’s internal streaming apps, audio/video sync is perfect, including Atmos content on Netflix, Vudu etc. Verified via Sonos app that it is receiving full Atmos signal. 

    When I try to listen to Dolby content coming from my external devices, the audio is noticeably behind the video.

    • Dolby Atmos content from the Chromecast or Xbox works but there is significant delay to the point of unwatchability
    • Non-Atmos Dolby 5.1 content from Chromecast or Xbox is a little bit delayed… noticeable if you’re looking for it.
    • PCM audio from Chromecast or Xbox has no sync issues. 

    I’ve messed with all the various audio settings in my TV to make sure any sort of additional processing is removed. I’ve also tried playing with the delay, because LG does offer the option to move sound earlier, but moving it as early as it goes (-5 in the settings) doesn’t fix it enough on Atmos (also it’s not a great fix given that the TV is applying this negative delay to all content on a given input uniformly regardless of audio format. 

    I’m totally at a loss on what to do. Buying some third party audio splitter like the Sharc makes the elegance of the Sonos a moot point. And this seems like a pretty systemic issue with many popular TV manufacturers. Even with all the various Sonos and Reddit forum posts, plus this Guardian article (https://www.theguardian.com/money/2020/sep/06/that-syncing-feeling-when-your-soundbar-lets-you-down), I’m surprised more people aren't complaining, because I don't think my TV/component combo is any sort of “edge case”… it’s pretty common. Are most people just using their TV’s streaming apps exclusively for Atmos content and therefore not seeing the delay?

    From what I understand, even if I upgraded to a new TV like the LG CX that has HDMI 2.1 and eARC, this lip sync would still be a problem because neither Xbox One X nor any streaming box is HDMI 2.1 compatible so it couldn’t utilize more advance synchronization on those devices. 

    Where’s the list of popular high quality HDTVs that have been verified as not having this issue with external devices running Atmos?

    I really love the look and the sound and the simplicity of the Sonos Arc, and I don't want to return it, but I may be forced to exchange it for a soundbar that doesn’t rely on ARC and just does a more standard receiver-style HDMI passthrough to avoid these audio delays. 

    Does anyone have any other suggestions before I throw in the towel?

    Thanks!
    Ben 

     

    You actually answered your own question, whether you like the solution or not. The Sonos ar  Soundbar is designed to work with eARC and getting dolby atmos at lossless TrueHD. Anything else and you aren't getting it's potential. 

    So the answer you stated regarding PCM output allowing the audio to be synced up with the video is typically accurate. When the TV sends out the sound as pcm, that means it has already processed the sound and output it in a format that will be able to be sent out to the speakers via another device (we won't go too far into details). Since your TV is the one doing the converting, it knows when to send that audio signal out and how long it's own video processing delay is currently taking so it can send that audio out at a perfect time and the receiving Soundbar can pretty much instantly play it since it's already been converted to an uncompressed format (PCM) from a compressed format (DD, DD+, etc.). 

    The downside to this is that obviously you won't get native atmos capabilities once that tv converts an atmos signal to pcm. The native player needs to do that since it's not just simply channels anymore from where the sound comes from, but a spatial way of recording all around you basically. Anyways, surround systems or sound bars will up mix your content to what it is capable of doing and usually sounds pretty darn good. 

    What are the reasons you don't want to use PCM in the mean time until you can get an eARC capable TV, or one of those splitters that do lip sync with any format you want to send. I forgot the name, but it's a couple hundred $ to buy. And yeah, for eARC to work, only the sending device and receiving device need that to work as far as I know (someone correct me if I'm wrong) if everything is setup properly settings wise and you're outputting the sound out from the eARC port of the new tv (or splitter if you want to go that route), lip sync should work no problem. It is a mandatory standard now for all of these new hdmi devices to mandate lip sync support. There is only going to be one eArc out port on a television so to say that all the input devices would have to support it as well may not be true as their ports aren't labeled eARC or anything. The TV handles all of the content from the input device such as an Xbox and negotiates with the sound bar on what to play when, based on delays. I don't believe the Xbox has to do anything on its part. 

    Austiopath
    Contributor I
    January 20, 2021

     @Bulletbling. Thank you for the quick response. A couple thoughts:

    • In all the literature and press surrounding the Sonos Arc, it was clearly stated that the biggest “sacrifice” one makes by having only an ARC compatible TV (not eARC) is the inability to decode uncompressed TrueHD Atmos… but compressed DD+ Atmos would still work fine over ARC. This was a fine tradeoff for me since I don’t watch BluRays and all my Atmos content is streamed anyway or via Xbox One X. What certainly is not mentioned out there in the world is that almost all major ARC televisions also have a habit of introducing soul-crushing audio delay through any external HDMI input device pumping out Atmos or even regular 5.1
    • Switching to PCM to avoid sync issues is more than a slight compromise IMO. At least on my TV (and perhaps on all ARC) if I switch the LG to PCM mode it outputs all surround sources (Atmos, Dolby Digital 5.1) to stereo 2.0 audio. Didn’t pay this much for an Atmos soundbar to watch in stereo.
    • I actually don’t feel entirely confident that upgrading to an eARC TV would solve all my problems. There seems to be plenty of threads on this forum, reddit, etc with LG CX owners, for example, complaining about the same issues. Is there a confirmed list of eARC compatible TVs that are confirmed to work perfectly sending an Atmos bitstream to the Sonos Arc over eArc from external HDMI devices (not TV’s internal apps)? I am probably going to upgrade my TV to a 2021 model in the near future but for now I have no confidence that things on my Xbox Series X or Chromecast with Google TV will work perfectly with true Atmos bitstream decoded by the Sonos. 

    I don’t feel like this is a case of “buyer beware”… I do my research and I knew I was sacrificing ability to get Dolby TrueHD Atmos and was fine with that. If folks want to buy a $200 splitter thingy so they can route uncompressed audio from their BluRay to their Arc, I get it...but I don’t feel like “you should have known” applies to this sync issue. I have to imagine the vast majority of Sonos Arc owners today have ARC TVs, not eARC TVs, so they are all experiencing this somewhat fatal flaw. 

    You actually answered your own question, whether you like the solution or not. The Sonos ar  Soundbar is designed to work with eARC and getting dolby atmos at lossless TrueHD. Anything else and you aren't getting it's potential. 

    So the answer you stated regarding PCM output allowing the audio to be synced up with the video is typically accurate. When the TV sends out the sound as pcm, that means it has already processed the sound and output it in a format that will be able to be sent out to the speakers via another device (we won't go too far into details). Since your TV is the one doing the converting, it knows when to send that audio signal out and how long it's own video processing delay is currently taking so it can send that audio out at a perfect time and the receiving Soundbar can pretty much instantly play it since it's already been converted to an uncompressed format (PCM) from a compressed format (DD, DD+, etc.). 

    The downside to this is that obviously you won't get native atmos capabilities once that tv converts an atmos signal to pcm. The native player needs to do that since it's not just simply channels anymore from where the sound comes from, but a spatial way of recording all around you basically. Anyways, surround systems or sound bars will up mix your content to what it is capable of doing and usually sounds pretty darn good. 

    What are the reasons you don't want to use PCM in the mean time until you can get an eARC capable TV, or one of those splitters that do lip sync with any format you want to send. I forgot the name, but it's a couple hundred $ to buy. And yeah, for eARC to work, only the sending device and receiving device need that to work as far as I know (someone correct me if I'm wrong) if everything is setup properly settings wise and you're outputting the sound out from the eARC port of the new tv (or splitter if you want to go that route), lip sync should work no problem. It is a mandatory standard now for all of these new hdmi devices to mandate lip sync support. There is only going to be one eArc out port on a television so to say that all the input devices would have to support it as well may not be true as their ports aren't labeled eARC or anything. The TV handles all of the content from the input device such as an Xbox and negotiates with the sound bar on what to play when, based on delays. I don't believe the Xbox has to do anything on its part. 

     

    Bulletbling
    Lyricist III
    January 20, 2021

     @Bulletbling. Thank you for the quick response. A couple thoughts:

    • In all the literature and press surrounding the Sonos Arc, it was clearly stated that the biggest “sacrifice” one makes by having only an ARC compatible TV (not eARC) is the inability to decode uncompressed TrueHD Atmos… but compressed DD+ Atmos would still work fine over ARC. This was a fine tradeoff for me since I don’t watch BluRays and all my Atmos content is streamed anyway or via Xbox One X. What certainly is not mentioned out there in the world is that almost all major ARC televisions also have a habit of introducing soul-crushing audio delay through any external HDMI input device pumping out Atmos or even regular 5.1
    • Switching to PCM to avoid sync issues is more than a slight compromise IMO. At least on my TV (and perhaps on all ARC) if I switch the LG to PCM mode it outputs all surround sources (Atmos, Dolby Digital 5.1) to stereo 2.0 audio. Didn’t pay this much for an Atmos soundbar to watch in stereo.
    • I actually don’t feel entirely confident that upgrading to an eARC TV would solve all my problems. There seems to be plenty of threads on this forum, reddit, etc with LG CX owners, for example, complaining about the same issues. Is there a confirmed list of eARC compatible TVs that are confirmed to work perfectly sending an Atmos bitstream to the Sonos Arc over eArc from external HDMI devices (not TV’s internal apps)? I am probably going to upgrade my TV to a 2021 model in the near future but for now I have no confidence that things on my Xbox Series X or Chromecast with Google TV will work perfectly with true Atmos bitstream decoded by the Sonos. 

    I don’t feel like this is a case of “buyer beware”… I do my research and I knew I was sacrificing ability to get Dolby TrueHD Atmos and was fine with that. If folks want to buy a $200 splitter thingy so they can route uncompressed audio from their BluRay to their Arc, I get it...but I don’t feel like “you should have known” applies to this sync issue. I have to imagine the vast majority of Sonos Arc owners today have ARC TVs, not eARC TVs, so they are all experiencing this somewhat fatal flaw. 

    You actually answered your own question, whether you like the solution or not. The Sonos ar  Soundbar is designed to work with eARC and getting dolby atmos at lossless TrueHD. Anything else and you aren't getting it's potential. 

    So the answer you stated regarding PCM output allowing the audio to be synced up with the video is typically accurate. When the TV sends out the sound as pcm, that means it has already processed the sound and output it in a format that will be able to be sent out to the speakers via another device (we won't go too far into details). Since your TV is the one doing the converting, it knows when to send that audio signal out and how long it's own video processing delay is currently taking so it can send that audio out at a perfect time and the receiving Soundbar can pretty much instantly play it since it's already been converted to an uncompressed format (PCM) from a compressed format (DD, DD+, etc.). 

    The downside to this is that obviously you won't get native atmos capabilities once that tv converts an atmos signal to pcm. The native player needs to do that since it's not just simply channels anymore from where the sound comes from, but a spatial way of recording all around you basically. Anyways, surround systems or sound bars will up mix your content to what it is capable of doing and usually sounds pretty darn good. 

    What are the reasons you don't want to use PCM in the mean time until you can get an eARC capable TV, or one of those splitters that do lip sync with any format you want to send. I forgot the name, but it's a couple hundred $ to buy. And yeah, for eARC to work, only the sending device and receiving device need that to work as far as I know (someone correct me if I'm wrong) if everything is setup properly settings wise and you're outputting the sound out from the eARC port of the new tv (or splitter if you want to go that route), lip sync should work no problem. It is a mandatory standard now for all of these new hdmi devices to mandate lip sync support. There is only going to be one eArc out port on a television so to say that all the input devices would have to support it as well may not be true as their ports aren't labeled eARC or anything. The TV handles all of the content from the input device such as an Xbox and negotiates with the sound bar on what to play when, based on delays. I don't believe the Xbox has to do anything on its part. 

     

    I can completely understand your frustrations. And yes, it is common unfortunately for the TV side of things to cause these delays and there's not much Sonos can do about it other than to say eARC in theory resolves it due to mandated lip sync support for all devices that have eARC support.

    Regarding the PCM stereo output, most mid range and up tvs these days will be able to output PCM above stereo, but not all still, which is a bummer and what you are facing. The good thing is that the Arc will still simulate the PCM output to surround/Atmos and receivers or Soundbar generally do a pretty fine job of "simulating" this functionality. I know it is not what you paid for and I'd be upset too. It's just that the TV you have is not the recommended/ideal type of device to use with the ARC. Of course it'll work and all, but full features aren't guaranteed and I do agree that since release of the ARC, Sonos should include a disclaimer that tvs without eARC support could have lip sync issues since this is sadly common! The TV manufacturers guilty of this problem should have this down pat by now because not all of them do this.

     

    Sorry I couldn't give you better news. Unless your tv gets some type of software update to have a setting to assist further in solving or actually solve this delay issue, you can't do much. 😞

     

     

    Ken_Griffiths
    Ken_Griffiths
    January 20, 2021

    I also think LG acknowledged the issue with some of their TV’s and introduced lip-sync features in their TV settings, as briefly outlined here:

    https://www.lg.com/ca_en/support/product-help/CT20098005-1412236386115

    It seems most TV manufacturers (including LG) have improved things with faster processors in their TV sets, one such example is the LG C9’s a9 (gen2) processor and the fact the manufacturers have begun to introduce the helpful audio pass-through on their HDMI/eARC ports too.

    At the end of the day, products like the Sonos Arc, can only ever output its audio once it has been received - so this lip-sync delay is most likely down down to the connected device.

    If TV’s are not upto the mark, it makes some sense to go with an HDFury Arcana type device, if not willing to upgrade the TV ...and there are, of course, some much cheaper ‘audio splitter’ options too, if you’re not bothered listening to any form of uncompressed audio. 

    Bulletbling
    Lyricist III
    January 20, 2021

    I also think LG acknowledged the issue with some of their TV’s and introduced lip-sync features in their TV settings, as briefly outlined here:

    https://www.lg.com/ca_en/support/product-help/CT20098005-1412236386115

    It seems most TV manufacturers (including LG) have improved things with faster processors in their TV sets, some such example is the LG C9’s a9 (gen2) processor and the fact the manufacturers have begun to introduce the helpful audio pass-through on their HDMI/eARC ports too.

    At the end of the day, products like the Sonos Arc, can only ever output its audio once it has been received - so this lip-sync delay is most likely down down to the connected device.

    If TV’s are not upto the mark, it makes some sense to go with an HDFury Arcana type device, if not willing to upgrade the TV ...and there are, of course, some much cheaper ‘audio splitter’ options too, if you’re not bothered listening to any form of uncompressed audio. 

    Exactly correct. Not much Sonos can really do other than to have you turn off any "effects" that are on in the app to reduce processing. It's all up to the tv since video should inherently take longer to process than audio, yet some manufacturers just can't get the sync right or don't have the options to correct it 100%. 

    Austiopath
    Contributor I
    January 20, 2021

    Can anyone confirm that all my problems will go away if I get an eARC compatible TV? That is: no sync issues EVEN on my externally connected Atmos-compatible devices, even if those external devices are not HDMI 2.1 compatible. It’s still unclear to me if for eARC lip sync to work perfectly, does just the TV and the Sonos need eARC? Or does the TV, the Sonos, AND the source device need to be eARC/2.1 compatible. 

    Again, the sync for Atmos on my TV’s internal apps works just fine, so it’s all about these external devices. But I just am NOT seeing universal confirmation that eARC TVs don’t have sync issues with the Sonos Arc in certain circumstances. Some people still seem to be having issues?

    Bulletbling
    Lyricist III
    January 20, 2021

    Can anyone confirm that all my problems will go away if I get an eARC compatible TV? That is: no sync issues EVEN on my externally connected Atmos-compatible devices, even if those external devices are not HDMI 2.1 compatible. It’s still unclear to me if for eARC lip sync to work perfectly, does just the TV and the Sonos need eARC? Or does the TV, the Sonos, AND the source device need to be eARC/2.1 compatible. 

    Again, the sync for Atmos on my TV’s internal apps works just fine, so it’s all about these external devices. But I just am NOT seeing universal confirmation that eARC TVs don’t have sync issues with the Sonos Arc in certain circumstances. Some people still seem to be having issues?

    This is tricky since in theory, eARC is mandated for lip sync. Whether that plays out perfectly amongst the rollout of it and software each manufacturer uses remains to be seen. I cannot help with this part as I'm not familiar with the percent success rate of the eARC "perfect" auto lip sync amongst all devices. Let's see if someone else has done testing with several eARC devices to reply here...

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