Using Playbar as Optical Line-In for Music - Compression??

  • 4 April 2018
  • 5 replies

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My objective is to achieve uncompressed music distribution from a CD player to 6 Sonos speakers, using an optical line-in. My CD player is connected via Toslink to my Playbar. My Playbar is grouped with my 6 Sonos P1's and P3's and I can hear music from each of those 6 speakers.

Question 1: Is the Playbar is streaming uncompressed WAV files to the 6 speakers, or is it using the SBC codec to compress?

Question 2: Within the app there is the option to select 'compressed' or 'uncompressed'. I would expect selecting 'uncompressed' to delay the sound approximately 2 seconds (as is the case using an analogue line-in to a Sonos connect). But this doesn't happen. The sound is either not delayed two seconds, or is equally delayed on 'uncompressed' or 'compressed' settings. Changing from 'c' to 'uc' makes no difference.

Question 3: When pausing the source music on the CD player sound on all Sonos speakers stops immediately. When I unpause the CD player it takes about 2 seconds for sound to reach the Sonos speakers.

My observations in 2 and 3 make me suspect that the 6 Sonos speakers are receiving SBC compressed sound from the Playbar. Please confirm.

[For the avoidance of doubt, although my configuration involves a Playbar, there is no TV and no surround speaker setup]

Grateful for any help received, cheers.

5 replies

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My mistake; the 2 second delay was introduced by one of my devices external to the Sonos environment. There is no 2 second delay, and Sonos has confirmed that the Playbar will distribute digitised audio it receives to other Sonos speakers without compressing it. Therefore, if anyone else wants to use Sonos to listen to uncompressed digital music from an external source then this is a way of doing so.
Or, rip your CDs in lossless FLAC format and sell the CD player and Playbar. (FLAC is compressed but this has no impact quality.)
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Hi John. Yep, done that. But I have friends who want to play their CDs from time to time and it's nice to be able to accommodate them. Having looked into this a bit further and measured bit rates I'm still not sure Playbar is distributing uncompressed. If you are interested I have opened the question of bit rates as a separate question called Playbar compression SBC FLAC. Thanks for replying. Mike.
Hi Mike. Yes I'll see what crops up on that front, thanks. Picking up one further point from your original post. The option in the Sonos app for 'compressed' or 'uncompressed' applies only to line-in, and for these purposes I don't believe the Playbar optical is regarded as a line-in. Therefore I would not expect this setting to have any impact in your scenario. Not 100% sure on that, but close to it.
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It seems Playbar does compress. Sonos now say:

"….the PLAYBAR compresses the audio to SBC and its bitrate is dynamic based on the number of components as well as the quality of the connection between said components. This would be equivalent to the Line-In compressed function…….[of Connect]"

So the idea of using Playbar as an uncompressed digital line-in is dead in the water. However, using the Playbar in this way might still be beneficial to some users:

The Playbar differs from the Connect in compressed mode in that the Playbar has no or at least a much smaller buffer. So anyone else who wants to inject music from external sources such as streaming music to an airport express such as:

Ipad Apple Music > Airplay > Airport Express > Toslink > Sonos Playbar

....will find that this setup has about 2 seconds less 'control latency' than a similar setup where instead AE is copper wired to a Connect in compressed mode. For example in the Connect setup changes to volume, or invoking pause, on the Ipad take 2 seconds to have audible effect, whereas in the Playbar setup they are 'instant'.