Audio Delay for HDMI Connected Dolby Sources
I recently purchased a C9 OLED (firmware 03.60.04) and SL8YG soundbar (firmware main 5484640-157053), and have been experiencing large audio delays of up to two seconds when playing Dolby content from an external HDMI device through the HDMI ARC port between the TV and soundbar.
As the C9 supports HDMI 2.1, I have all of my HDMI sources connected directly to the TV. This allows me to take advantage of VRR, ALLM, etc. Whilst I understand that the SL8YG does not currently support eARC (I am hoping this will be released in a future firmware update), it does support DD+ over ARC. This allows the TV to passthrough Dolby Atmos content using DD+ rather than Dolby TrueHD over ARC to the soundbar.
The problem, however, is that only PCM and DTS are passed through the TV without introducing any audio delay. As soon as the source switches to Dolby related content (Dolby Atmos, Dolby Digital, etc.) there is a significant delay in the audio being transmitted to the soundbar. I have bought certified premium HDMI cables, which have made no difference. I have also tried every possible configuration in the TV setting menu (AV Sync Adjustment, Bypass, etc.), all of which have made no difference.
The reason why I know the TV is at fault is because all internal apps on the TV (e.g. Netflix) do not experience this issue with Dolby content. My 4K Bluray player (Sony UBP-X700) does not experience this issue either when it is connected to the HDMI in on my SL8YG - the audio and video are in perfect sync. It is only external devices that are connected through HDMI directly to the TV and have to pass audio over HDMI ARC that experience this issue. FYI, I have verified that Optical also experiences this problem.
A great test is to plug an Xbox One X into HDMI 1 on the C9 and an SL8YG (HDMI ARC) into HDMI 2 (ARC) on the C9. From the Xbox audio out settings, you can manually set PCM which works perfectly (no delay), DTS which works perfectly (no delay), but Dolby Digital or Dolby Atmos will experience significant audio delays. Further, if you leave the Xbox set to Dolby Atmos and then override the C9 'Sound Out' to be PCM rather than Passthrough, the delay is improved (as a rough guide, passthrough of Dolby encoded content would be around 1s whereas decoded to PCM would drop this to around 300ms). This highlights that there is a problem with the way that the C9 is processing Dolby content from external HDMI connected sources, which causes the audio to lag the video - something that cannot be manually fixed by any available adjustment, not that this would be a viable solution if you wish to use other advertised features of the TV such as ALLM.
I have reached out to LG support a number of times but have been unable to advance this discussion to the appropriate engineering team. Can you please pass this information on to the relevant engineers and advise on when we can expect this functionality to be fixed?

0:00 - 1:00 - LG C9 Audio Settings and Firmware Version
1:01 - 1:20 - Issue with LG C9 not being able to receive 5.1 or 7.1 uncompressed (this should work regardless of whether ARC is being used or not, as the TV can convert 7.1 uncompressed to bitstream output for ARC)
1:21 - 1:40 - Stereo Uncompressed (perfect, no noticeable audio lag)
1:41 - 2:08 - DTS Digital Surround (very good, no noticeable audio lag)
2:09 - 2:40 - Dolby Digital (poor, up to half a second audio lag)
2:41 - 3:15 - Dolby Atmos (very poor, up to a second or more of audio lag)
3:16 - 3:48 - Stereo Uncompressed (perfect, no noticeable audio lag)
As the C9 supports HDMI 2.1, I have all of my HDMI sources connected directly to the TV. This allows me to take advantage of VRR, ALLM, etc. Whilst I understand that the SL8YG does not currently support eARC (I am hoping this will be released in a future firmware update), it does support DD+ over ARC. This allows the TV to passthrough Dolby Atmos content using DD+ rather than Dolby TrueHD over ARC to the soundbar.
The problem, however, is that only PCM and DTS are passed through the TV without introducing any audio delay. As soon as the source switches to Dolby related content (Dolby Atmos, Dolby Digital, etc.) there is a significant delay in the audio being transmitted to the soundbar. I have bought certified premium HDMI cables, which have made no difference. I have also tried every possible configuration in the TV setting menu (AV Sync Adjustment, Bypass, etc.), all of which have made no difference.
The reason why I know the TV is at fault is because all internal apps on the TV (e.g. Netflix) do not experience this issue with Dolby content. My 4K Bluray player (Sony UBP-X700) does not experience this issue either when it is connected to the HDMI in on my SL8YG - the audio and video are in perfect sync. It is only external devices that are connected through HDMI directly to the TV and have to pass audio over HDMI ARC that experience this issue. FYI, I have verified that Optical also experiences this problem.
A great test is to plug an Xbox One X into HDMI 1 on the C9 and an SL8YG (HDMI ARC) into HDMI 2 (ARC) on the C9. From the Xbox audio out settings, you can manually set PCM which works perfectly (no delay), DTS which works perfectly (no delay), but Dolby Digital or Dolby Atmos will experience significant audio delays. Further, if you leave the Xbox set to Dolby Atmos and then override the C9 'Sound Out' to be PCM rather than Passthrough, the delay is improved (as a rough guide, passthrough of Dolby encoded content would be around 1s whereas decoded to PCM would drop this to around 300ms). This highlights that there is a problem with the way that the C9 is processing Dolby content from external HDMI connected sources, which causes the audio to lag the video - something that cannot be manually fixed by any available adjustment, not that this would be a viable solution if you wish to use other advertised features of the TV such as ALLM.
I have reached out to LG support a number of times but have been unable to advance this discussion to the appropriate engineering team. Can you please pass this information on to the relevant engineers and advise on when we can expect this functionality to be fixed?

0:00 - 1:00 - LG C9 Audio Settings and Firmware Version
1:01 - 1:20 - Issue with LG C9 not being able to receive 5.1 or 7.1 uncompressed (this should work regardless of whether ARC is being used or not, as the TV can convert 7.1 uncompressed to bitstream output for ARC)
1:21 - 1:40 - Stereo Uncompressed (perfect, no noticeable audio lag)
1:41 - 2:08 - DTS Digital Surround (very good, no noticeable audio lag)
2:09 - 2:40 - Dolby Digital (poor, up to half a second audio lag)
2:41 - 3:15 - Dolby Atmos (very poor, up to a second or more of audio lag)
3:16 - 3:48 - Stereo Uncompressed (perfect, no noticeable audio lag)
Answers
A new firmware came out 2 days ago to download onto a usb stick. I haven’t tried it yet, but hopefully it addresses this issue.
C9 firmware revision 03.60.04 change log below:
1. Improvement
1) Amazon Alexa service ready. Need to download "Amazon Alexa" app from LG Contents Store. (USA, Canada, Mexico, France, Germany, Spain, United Kingdom, Austria, Ireland, Italy, Australia, India, New Zealand, Japan) (This Service will be available soon)
2) Improving Youtube voice service
3) Adding sound bar to Home dashboard
4) Fixed minor bugs.
I'm having the same issue. Atmos or Dolby digital has a solid 1-2 second delay , but DTS has no delay.
Would love to get Dolby Digital/Atmos/True HD working for hdmi sources via ARC/EARC... Internal apps work just fine with no delay.
I'd be interested to know whether anyone with an eARC capable soundbar or AV receiver experiences this issue as well.
Can you try the setup below and advise if the problem continues?
Xbox One X(MS Xbox) -- <HDMI>-- SL8YG(LG Sound Bar) -- <HDMI>--- C9(LG TV)
I own the Samsung HW-Q70R, and when I do
Xbox One X(MS Xbox) -- <HDMI>-- Samsung HW-Q70R, -- <HDMI>--- C9(LG TV)
I get NO Dolby audio delay. The issue only applies when I plug the xbox into the TV (Which I need for VRR support etc.) and use either ARC or EARC
I have exact same issue with my new LG 55C9PHA OLED I recently bought.
And I have a Nvidia Shield connected to HDMI3 on TV.
With the Nvidia I have no delay issues with Dolby Atmos. I use my Nvidia with Plex
But with Xbox One X set on bitstream and Dolby Atmos (with the Xbox app) I have a good second or so delay, the sound is behind with picture.
This is with games or with my cable box connect on Xbox, Plex on Xbox and Netflix app on Xbox.
If I change the sound settings on Xbox to DTS I have no delays with sound and even with Dolby Digital there is almost no delay.
If I use the Netflix app from the TV LG store I also have no delays with Dolby Vision/Atmos content.
And finally if I use my Onkyo as central hub with all my devices like Xbox, Shield, etc. connected to my receiver and the HDMI output to my LG HDMI 2 I have no delays in any sound with Dolby Atmos or anything else.
But I just wanted to use the eARC for the VRR and Auto Low Lantency mode and the Dolby Vision support.
So I really hope there will be a fix with firmware or anything soon so I can truly enjoy this great TV!
Regards,
Rogier
"My 4K Bluray player (Sony UBP-X700) does not experience this issue either when it is connected to the HDMI in on my SL8YG - the audio and video are in perfect sync. It is only external devices that are connected through HDMI directly to the TV and have to pass audio over HDMI ARC that experience this issue. FYI, I have verified that Optical also experiences this problem."
Thanks Jamal. If you could please provide us with updates as you receive them it would be greatly appreciated.
I've got the C9 and a Samsung Q90R soundbar, both of which support eARC. When i have my xbox one x plugged into HDMI1 on my C9, and the Q90R plugged into HDMI2 (ARC), with eARC and pass-through enabled, i get a significant audio delay when using dolby surround and dolby atmos settings.
When i set it to PCM or DTS, the audio delay goes away.
Plugging the xbox one x directly into the Q90R soundbar, and then the soundbar into the C9, the audio delay also goes away.
This is far from ideal, as i lose all the HDMI 2.1 features that are the C9's main selling points, such as VRR.
As i bought this TV to take advantage of eARC and VRR, i may be forced to return this TV if this issue doesn't get resolved.
I have a brand new C9 and I am suffering from the same issue. Dolby from Xbox or PS4 through HDMI-ARC suffers from a delay.
Sony STR-DH770 in a 5.1 speaker configuration, connected to the LG C9 HDMI-2 port for ARC.
On the LG, under Settings for HDMI-2, Sound Out is set to HDMI ARC, Digital Sound Out is set to PASS-THROUGH, eARC is OFF, HDMI Input Audio Format is set to PCM. Ultra HD DEEP color is enabled and the equivalent setting on the Sony AVR is enabled as well.
PS4 connected to Sony AVR has no problem outputting LPCM 5.1, or Dolby or DTS audio.
AppleTV 4K connected to LG HDMI-1, Dolby Vision and Dolby Atmos are both detected and enabled. HDMI-1 settings are same as above, except HDMI Input Audio Format is set to BITSTREAM,
The AppleTV can only output LPCM 2.0, Dolby Digital, and Dolby Atmos. There is considerable audio lag when sending any Dolby audio, resulting in audio coming after the video. If I connect the AppleTV to the Sony AVR, I have no issues with any audio format. However, my AVR cannot pass a Dolby Vision or Dolby Atmos signal to the LG; only HDR10 and regular Dolby Digital and LPCM 5.1, and the LG has a difficult time negotiating CEC when all my devices are connected to the AVR. For example, if everything is off, and I turn on my PS4, it will turn on the AVR, the TV, and the AppleTV, but the LG will endlessly cycle between the PS4 and the AppleTV (which the LG has detected that both are sharing HDMI-2 via the Sony AVR.
Xbox One S connected to the LG HDMI-3 and has similar audio lag issues as the AppleTV when sending a Dolby-anything signal. If I change the Xbox sound output to DTS or LPCM 2.0, there is no audio lag. I should note that the LG cannot sense that the Xbox is sharing the HDMI-2 port if I connect it to the AVR (which my Sony X700D could not detect either so that is a separate issue with Microsoft), but I lose out on Dolby Atmos, Dolby Vision, and 120hz refresh.
If I route all my source components to the Sony AVR, I get perfect 5.1 LPCM, DTS, and DD audio. However, I miss out on the C9s biggest features (ALLM, 120hz refresh, Dolby Vision, and Dolby Atmos). I could forego all those features and route everything through the AVR, however the C9 also has trouble negotiating which is the intended active source I’ve selected through the AVR, whereas my Sony X700D did not have this issue (which is a separate problem, but one which I hoped I could get around by using Dolby pass-through on the TV.)
Thank you for your attention.
I am concerned that no traction is being made on providing a fix in a future firmware update, which restricts the TV from performing as advertised. I understand there are other issues to address (such as the limited LPCM passthrough via eARC, etc.), however, this is a fundamental flaw that LG need to immediately action if they wish to stop customers from returning their OLED back to the stores and swapping to a competing TV.
Same as everyone else, although I went out and bought the LG SL10YG. Exactly the same issue with the C9.
I have tried Xbox One X and Apple TV 4K. Both fine straight into SL10YG, huge delay connected to the TV.
I am on 3.60.19 firmware (just released a few days ago for HomeKit/Airplay support). Obviously no better or I wouldn’t be here posting.
Seems common enough that this should be easily reproduced. Can we at least get an update on if the engineering team can replicate the issue?
If it’s not fixed soon I’ll just buy Sony oled.
All my devices suffer audio lag when using eARC. My nice soundbar has been rendered useless.
I will be returning this and claiming on false advertising if this issue is not sorted
Can you please request an urgent response from the engineering team regarding a timeline for this to be fixed?
If the engineering team cannot provide you with an immediate response, can you please private message me with either one of the engineer's email address or your supervisor's email address so that I can escalate this issue accordingly?
thanks
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