Hi @Corry P - Any update on this?

If it has been “requested many times” why can’t the engineers properly fix it? This thread is over 2 years old and it’s unfortunate that we have either…

A. Leave eArc on and get great Atmos, but SOFT LPCM.

B. Disable eArc because we don’t want to deal with the muddy/soft LPCM sound format when dealing with non-Atmos content. 

Other soundbars appear to handle LPCM just fine…all we’re asking for is that LPCM and Dolby Digital sound relatively similar volume wise. There’s no reason that uncompressed LPCM should sound softer that Dolby Digital. 

Sorry if this is a stupid question but why would you use lpcm when you can use Atmos? 

Hi @bignicknicknick 

If any change is ever implemented, there’s a very good chance that you will know before I do. If I do find out before you do, there’s a very good chance I would not be free to share it the information with you anyway.

So, no, I don’t have any further information to share, I’m afraid.

Hi @Naekyr 

@bignicknicknick’s Apple TV will apparently only output Atmos or Dolby Digital, not both, or only LPCM, depending on the setting.

Let me start by saying, I was always in the camp of "sonos is doing something goofy with lpcm. But after I have messed around with different sources and titles, a lot of the issue comes down to how the movie was filmed (mainly what era) and what service is pumping it out. I think something could be down with a boost option for some poorly recorded movies and junk service providers, but ultimately I think a lot of the blame falls on the studios and the streaming providers.

Anyone wants to see what I am talking about....go to Paramount+, open Arrival and watch about five minutes worth from about the 32 minute mark. This will be in Multichannel PCM. This has far more punch than anything else I have listened to in multi channel PCM. Is it just Paramount? Or is it how the studio filmed this? Or a combination of both? But this five minute test alone will show you there is far more than just Sonos going on here. I can also tell you this, the original Jurrasic Park when it was on Max, would blow the windows out on the TRex growl and that was LPCM. It now isn't on Max and can only be watched on Spectrum. Same exact scene is coming through in LPCM like Max....and the entire thing has maybe half the punch it used to have when it was presented on Max. I haven't dealt with BluRay in forever since they shoved us all to streaming, but I'd love to hear what people get when they put in old BluRay disc's of movies such as Days of Thunder. Currently that's only available on Paramount+ and you have to crank the hell out of your system to even hear it. I use to own that  movie on disc and I know om bluray it had a massive soundstage...now on streaming it is awful.

Hi @Missionsparta 

One thing I can guarantee is that your streaming services are not providing you with LPCM - something in your playback chain must be decoding to it prior to your Sonos equipment receiving it, as LPCM is completely uncompressed and it would take too much server bandwidth to supply everyone with uncompressed audio (not to mention that storing thousands of movies with LPCM would take a lot of unnecessary space).

The only place you’re ever likely to receive a movie with LPCM in the original stream is from BluRay, and even then, I don’t think it likely. LPCM is a fall-back position - BluRay players can extract LPCM from a compressed (but lossless) format knowing that any TV or AV Receiver connected with HDMI will be able to play it (eARC is needed to then pass it to an external audio device like Arc because different wires are used for audio with HDMI-ARC as compared to HDMI). If LPCM is not sent, the TV must know how to decode the given compressed stream, or at least be able to pass it on to the audio device unaltered - neither of which is guaranteed. While it is mandatory that BluRay players support LPCM soundtracks, I don’t think you’ll find many movies with LPCM actually on the disk - they take up too much space best kept for 4K video.

You are largely correct in your findings, however. A UHD disk will often have multiple high quality soundtracks, as well as lesser 5.1 ones. How these are mixed is not only down to the original sound engineer who worked with the director, but also the BluRay authoring engineers. Which of these is used for streaming is up to the streaming service’s engineers and they may well adjust things themselves - I don’t know for sure.  The result of this is exactly what you found - the same movie on different services could easily be at differing volumes, even with the same audio format chosen.

One more point about LPCM is that it is what all audio players will use internally - it’s literally the only thing that the microchip responsible for converting digital audio into an analogue signal for amplification understands. Regardless of what format you are listening to, or what source it came from, it was converted to LPCM (or PCM for stereo) before you heard it so the source is always paramount when it comes to how loud it sounds - there’s nothing inherently quiet about LPCM, though if you are receiving it, it is often from a high-dynamic-range source and therefore not as loud as Dolby Digital or stereo PCM.

I got typing faster than my brain was working. I meant PCM and Miltichannel PCM, not loseless. Sorry about that. I feel like going and borrowing a Bluray player and getting some disc's to test this. As far as streaming goes, it is amazing what happens to the same movie with multichannel PCM when it is moved from one service to another. I'm sure older movies on bluray also suffer from studio limitations at the time of filiming.

Hi @Missionsparta 

Multichannel PCM and LPCM are the same thing, as far as I am aware (and both are lossless); I can find references to McLPCM in my internal documentation. The terms are largely interchangeable.

The worst part of it all is that engineers who have never even met the director often remix soundtracks for DVDs and BluRays. Although it was video that was affected, this was illustrated by The Matrix movies - on DVD and VHS, the colour grading (green for in the Matrix, blue for the Real World) was exaggerated beyond the level the Wachowski’s ever wanted - it was only fixed with the UHD release. I sure the same happens with audio, only probably more so.

Im able to get titles to play in Multichannel PCM over streaming services. So not saying there isn't loseless multichannel PCM, but im getting some form of compressed version. But yeah, I think the different studios, different services, different manufacturing, etc all play major effect in what we are getting. I know it's just streaming, but listening to titles be shuffled from one service to anther and getting completely different results tell you that the human element 100% comes into play and I'm sure the same can happen with blurays.

I either can do the following…

- eARC On - True Dolby Atmos and LPCM. True Dolby Atmos sounds great but LPCM is very soft and muddy. 
 

- eARC Off - Dolby Atmos and Dolby Digital. Dolby Atmos sounds good, but it’s not True Dolby Atmos…and Dolby Digital sounds great and loud. 
 

For some reason, LPCM on the Arc (which is uncompressed) sounds soft and somewhat muddy compared to Dolby Digital. Not to mention the volume needs to be adjusted a lot more with LPCM between content. 
 

A non Sonos soundbar doesn’t have this soft/muddy sound when playing LPCM.

Hi @bignicknicknick 

Your Arc will basically be playing what it is told to play - if LPCM sounds different to other formats (soft and muddy), it’s because your Apple TV (or TV) is delivering it that way. Different hardware is decoding whatever came before LPCM (it’s unlikely that the source media contained a LPCM track), and that must be the reason for things sounding differently.

If volume is the only difference, however, I can only suggest altering the volume with the controls.

I hope this helps.

This thread is 2 years old and people are having issues with their ARC and many different devices while playing LPCM. 

It can’t be the Apple TV because other sound bars don’t sound low/muddy when paying LPCM. 

Very frustrating as we’re 2 years into a thread with various people saying the same thing and nothing being done about it.

If you are using Apple TV,  like I said earlier, go to Paramount+ and play Arrival. Go to the 30 minute mark amd listen for five minutes or so. You will be getting 5.1 PCM (you can't get LPCM through streaming). It's rocking well on my system as far as punch and volume. Granted, this is one of the few examples I can find of this, which points back to provider and the studios recording.

Hi @bignicknicknick 

Well, I suppose it depends upon what you mean by “low/muddy”. If someone calls in saying their Sonos Arc sounds quieter when playing LPCM, the understandable response will likely be to turn up the volume - movies are mixed at differing volumes. We’re not going to record this as a report of a bug, because it isn’t one. With compressed formats, we need to decompress them prior to playback and I have been told that as a part of that process we increase the gain - something that doesn’t happen with LPCM as it does not need decoding (I think I mentioned this earlier in this thread). This, however, only addresses LPCM often being quieter than other formats, and not it being “muddy”, so I again encourage you to get in touch if “muddy” doesn’t just mean quiet - in fact, I wouldn’t even mention the volume except as a side-note. “Degraded audio quality” would be the phrase I would use.

Also, as mentioned previously by myself and others, LPCM generally isn’t something you’ll find - no streaming service will supply it, and I would have to see visual proof of it being on a Blu-Ray before I was inclined to believe any such report, so we necessarily come to the fact that any LPCM stream you see reported in the Sonos app has come from either a) the live audio of a games console outputting LPCM specifically while playing a game or b) the result of a device further up the media playback chain decoding the actually-supplied, compressed audio stream in whatever format into LPCM before the Arc ever receives it, in which case it’s not really for us to do anything about it - anything we do do will adversely affect people who don’t have the same equipment as you.

I can’t comment on soundbars from other manufacturers, but if you’ve done a side-by-side comparison with LPCM and other formats and found Arc to definitely be inferior with LPCM specifically, then I would ask that you contact our technical support team and tell them as much, as I’m sure our engineers would like to see/hear some video proof and diagnostics. If you are going by what other people report, remember that you are on the internet and things should be taken with a few grains of salt - but that just means that it’s them that should be getting in touch rather than you. If true, we’d love to know. 

Personally, I watch a fair bit of content, and I find myself adjusting the volume for nearly every piece - with YouTube videos, I’ll be at anything from 10 to 16 volume (I put this down to the inexperience that YouTubers have with audio engineering, as compared to professionals working in a TV studio, for example). With TV programs (mostly Dolby Digital or AAC stereo), 12 is common. With movies, however, it can vary from 12 to 30. I usually only need to go as high as 30 if the source format is Dolby TrueHD, but it is not in any way every TrueHD movie that needs to be that high - just the occasional, random one. 18 is more common, but then I often want movies to be a bit louder anyway. Full disclosure - I have an Amp, which does not support LPCM or Atmos, and my nVidia Shield transcodes unsupported formats on-the-fly (but without altering the volume).

I hope this helps.

Hello Corry,

I understand that you might be getting tired of this thread, but it also makes clear that many users are really struggling with this issue. You mention that LPCM is generally not used by streaming services or found on Blu-rays. While it's true that it's rare, there are Blu-rays with an LPCM track. You'll mostly find these on music Blu-rays. Attached is a link to a sample file that I've made from a Justin Timberlake Blu-ray which has 3 audio tracks:

1. Dolby Digital with a bitrate of 0.6 Mbps
2. PCM 2.0 with a bitrate of 2.3 Mbps
3. PCM 5.1 with a bitrate of 6.9 Mbps

To clarify, this is a 1:1 sample of a Blu-ray without modifying the video or audio.

I play this file with a media player with bitstream passthrough. So there's no conversion taking place to LPCM. The audio is as it is, and the Sonos Arc plays it as it is.

You mention that you don't own a Sonos Arc yourself, but I assume you can find one or know someone who has one. If you've listened to this sample and don't hear that the LPCM track(s) sound significantly worse than a Dolby Digital track with a fraction of the bitrate, then I don't know what else to say.

I don't know if I'm allowed to share this link here. If not, you can remove it, but please forward it to one of your engineers first. It can't be that everyone in this thread is imagining this.

Here's the link to the file (3.5 GB)"

https://drive.google.com/drive/folders/1y7fglFGFXvf7obTTe1W5PCqHDBYfwF7S?usp=sharing

I hope this helps!

It seems the sample isn’t quite right. I’ll try to upload a new one once I get the chance. Cutting just a piece out of large MKV isn’t as easy as it sounds. Apologies. 

I uploaded a new Sample at the same link 

Moderator edit - link removed to avoid copyright issues

I hope you'll take the time to listen to it or forward it to your enginering team. 

To clarify, my setup is Arc, Era 300 as surrounds and Sub (gen 2).

Hi @Whistler 

I confess I didn’t really think of music BluRays - thanks for setting me straight!

I’ll see if I can get someone with an Arc to give that file a listen - thank you for the effort you obviously put in to do that.

Hi Corry, 

No problem!  Needless to say you need to play this on a device that does bitstream Passthrough and not for instance a Apple TV 4K that converts everything to LPCM by default to hear the difference between the tracks.

Hi @Whistler 

I passed the link to a colleague and asked him to read these last few posts on this thread for context.

He played the file with Kodi on a nVidia Shield to his Arc, but was unable to discern any difference between the Dolby Digital and LPCM tracks besides the volume.

He did notice, however, that the two tracks were not identical. The LPCM track appears to have had a filter of some kind applied to it:

As we were unsure as to why he couldn’t hear a difference, he extracted just these centre channel tracks to FLAC and sent them to me - I couldn’t hear a difference either.

So, although we were both unable to discern any audible differences, there does appear to be a difference in how the two tracks were mastered. We have to assume therefore, that either there is no significant difference, or there is, but only when using the equipment that you are using and it’s due to the difference in mastering - with Passthrough/Bitstream, this should not be happening, however, though it’s not unknown for “Passthrough” to be an inaccurate description of what’s happening when it comes to some TVs.

He also tested with both Night Mode and Speech Enhancement disabled and enabled, but still no difference was perceivable.

So, long story short, we cannot confirm your findings. At this point, as far as we are concerned, everything appears to be working as intended and we don't consider this to be an issue.

All we can suggest is that if things sound worse when listening to LPCM, don’t use LPCM - I don’t mean to be flippant, but I’m not sure what else to say at this point.

I have removed your links to the file to avoid copyright issues.

I hope this helps.

Hi @Whistler 

I passed the link to a colleague and asked him to read these last few posts on this thread for context.

He played the file with Kodi on a nVidia Shield to his Arc, but was unable to discern any difference between the Dolby Digital and LPCM tracks besides the volume.

He did notice, however, that the two tracks were not identical. The LPCM track appears to have had a filter of some kind applied to it:

As we were unsure as to why he couldn’t hear a difference, he extracted just these centre channel tracks to FLAC and sent them to me - I couldn’t hear a difference either.

So, although we were both unable to discern any audible differences, there does appear to be a difference in how the two tracks were mastered. We have to assume therefore, that either there is no significant difference, or there is, but only when using the equipment that you are using and it’s due to the difference in mastering - with Passthrough/Bitstream, this should not be happening, however, though it’s not unknown for “Passthrough” to be an inaccurate description of what’s happening when it comes to some TVs.

He also tested with both Night Mode and Speech Enhancement disabled and enabled, but still no difference was perceivable.

So, long story short, we cannot confirm your findings. At this point, as far as we are concerned, everything appears to be working as intended and we don't consider this to be an issue.

All we can suggest is that if things sound worse when listening to LPCM, don’t use LPCM - I don’t mean to be flippant, but I’m not sure what else to say at this point.

I have removed your links to the file to avoid copyright issues.

I hope this helps.

Hi Corry,

Thank you for putting in the effort you did. I would not use LPCM if I didn't have to.  It is just that normally the Apple TV 4K is my “go-to” device for playing my own RIPS. It's kind of ironic that this is because it converts everything to LPCM so I don’t have to worry about playing DTS-HD MA which Sonos does not support. I guess I can only hope that Sonos will someday support all major (lossless / spatial) formats and Apple allowing Passthrough (again). But not seeing either happening anytime soon. Never the less, thanks again for investigating. I'll try to live with it ;)

Hi @Whistler

You are very welcome!

Like my colleague, I have a nVidia Shield Pro, and when I play a file with DTS-HD, Plex will automatically extract (not transcode) the DTS core from that and pass it along to my TV/Amp. This would also work with an Arc, and while DTS isn’t DTS-HD, it’s a lot better than Dolby Digital. The Shield has several output format options (but will only transcode to Dolby Digital) - it might be worth a look. Mind you, Plex may behave the same way on Apple TV - I don’t know. I do know another program similar to Plex called Emby does not extract the DTS core, so perhaps it depends on the software you are using rather than the Apple TV itself?

After reading your earlier post, I had assumed you were using the Zidoo - have you tried it?

Currently I am using Apple TV 4K + Infuse. Which converts everything to LPCM which should be identical to the original source. I really would like the best possible quality I can get and this solution should in theory be a “one-that-does-it-all” solution. I used the Zidoo because I also want the best Atmos experience with Dolby TrueHD + Atmos, which the Apple TV 4K cannot do. (So much for that one-that-does-it-all solution right lol).  I have also tried the Nvidea Shield but did not really like it. I am more of a Apple eco-system guy. Thanks for your input, and maybe I have to reevaluate my setup in the near future ;)

i have same issue, 

Multichannel PCM 5.1 is sounding too bad in my Sonos arc.  I have to set volume to 80 to get decent sound.  where native Dolby atmos sound very good.  

Hello, 

since the update to v16.0 i am facing an issue with lpcm. It is so quiet, that even if i crankup the volume to max i can't hear a thing. Before the Update i never had any issues wuth my Sonos Playbar. When switching to dolby on my ps5 i am facing issues with the loudness on hulu and sky q. I hope you can help me with my issue? 

Best Regards 

Finn