Sonos - Arc and Amp - Easy Way to Optionally Choose to Play through Both or Just Arc

I’m afraid the laws of physics prevent syncing grouped rooms with the TV source.   The low latency, one way, 5 GHz connection between the TV source and surrounds/Sub allow for them to be in sync with the TV video, but the signal has trouble passing through walls or floors.  The more penetrating 2.4 GHz signal used for grouping can pass through walls and floors, but it is not low latency, and thus needs a larger buffer. The larger buffer is what adds the 75ms delay. 

Sending ‘demanding’ PCM stereo (uncompressed) TV audio across a wired/wireless LAN to play on ‘grouped’ rooms is always going to need a certain sized buffer - Sonos uses ~75ms by default which works for most (not all) users & their home networks… To keep things in A/V sync, you need the ability to buffer/delay the video on screen to be aligned with the grouped playing speakers - there are some TV’s/devices already that can help achieve these things. Apple-TV and some LG & Sony TV’s have lip-sync features, but really it needs the A/V industry to come up with a firm solution.

That said ‘bonded’ Sonos players over a 5Ghz ad-hoc network seems to be able to achieve lip-sync with two surrounds and up-to two Subs for the majority of users, but more than that amount of players may perhaps prove difficult.

Anyhow, lip-sync is really only necessary if all the ‘grouped’ Sonos players are in the same physical room - if they are placed elsewhere in the Home, then the delay often does not become an issue… and for me a current Sonos HT setup with surrounds and Subs is plenty for most folks viewing locations in a majority of Homes in any event. So I’m not sure the A/V industry would want to invest in having more than say a 7.2.setup in a room.

If this does ever happen, I suspect it may be years, rather than months, before we see it.

Thank you again for the insights.

From the audio side, I understand (from other online comments from users) that Sonos sync works by distributing the audio asychronously, then coordinating buffered playout via a shared clock. I also read that the Sonos systems are always self-correcting for synchronization to keep things aligned within 1-2ms alignment (not really discernible to the human ear). It seems like Sonos grouped systems should be able to coordinate these elements to play back TV audio signals as well.  Sonos Engineering -- please take up the challenge (if you have not done so as yet)!

Thanks,

As I said, it can’t be done.  Part of the sync process is that a buffer is built up, so that any missed/corrupted packets can be requested again, or any intermittent wireless interference can be overcome by the time the buffer runs out.  Using the low latency direct 5 GHz connection for surrounds and Sub, that buffer can be small, small enough to not affect lip-sync with the video.  That small buffer can’t be used for grouping, because dropouts would occur due to the harsher conditions of going room to room and floor to floor, so the buffer has to be larger, and the signal has to be 2.4 GHz instead of 5 GHz.

So until the industry standardizes on a method to delay the video 75 ms in order to get all units to sync up, there’s nothing Sonos can do.  Physics wins every time.

Typically in the source device video processing lags behind audio. Some TV’s and source devices allow audio delay adjustment. You may be able to work with all of these adjustments and the SONOS adjustment to arrive at a reasonable compromise. In some cases you can skew the soundbar and source adjustments to deal with the 75ms Group latency without seriously compromising lip sync. Of course your mileage will vary.

A big annoyance in the US is that lip sync may vary from one TV program to the next. Typically the music channels are more consistent. From discussions I’ve read here in the Community, it seems that this is not a big issue in Europe.

Thanks again all. It is also an annoyance in Canada too. And taking advantage of the video delay relative to the audio (due to TV video processing), I am pretty hopeful that Sonos Engineering can look into this sync issue in the Sonos groups to avoid the resultant echoing that so many users describe in their groups when playing TV audio. That may take a bigger effort - but hopefully just some fancy firmware/software updates on our end and maybe a new Sonos “box” we buy that takes the video and audio signals together, holds them up appropriately and gets the audio aligning across the speaker groups and feeds the video at just the right time to the TV to keep lip sync right. With feedback and audio alignment self correcting ongoing and auto-adjusting for poor sound/video alignment program by program. (Hopefully without having to have yet another box with a camera and microphone that “watches” and “listens” and sends feedback to the first box.) We’re counting on you Sonos Engineering.

You’re still missing the whole ‘physics’ thing that @jgatie is discussing. There’s a strong doubt here that any amount of Sonos engineering can overcome the natural laws of physics. No matter how hard they try. 

On the contrary, with Physics and Engineering, I believe that this is all very do-able. The first part - defining the problem - is already done. The need is identified. The challenge is on!

Sigh.

It’s clearly an issue of Sonos not being motivated enough to rewrite the entire underlying network design of their software. Anything can be done in software!