Line-In compression

  • 2 October 2013
  • 8 replies
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Hi - it is a while since I looked at this and I have a few queries.

I presume that it is digital stream compression not audio compression/limiting as used by radio stations, that wouldn't make sense?

I see that there is now an "automatic" option. Does any one know exactly what that means?

Do we know if it is lossless (as per FLAC which achieves quite good compression wrt WAV)? Or is it lossy (as per MP3)?

I am asking because I have been using line in from my Hi-Fi and recently it has started to break up. I found that it was set to automatic. Changing it to compressed removes the problem - I have not tried using uncompressed yet.

8 replies

Hi - it is a while since I looked at this and I have a few queries.

I presume that it is digital stream compression not audio compression/limiting as used by radio stations, that wouldn't make sense?

I see that there is now an "automatic" option. Does any one know exactly what that means?

Do we know if it is lossless (as per FLAC which achieves quite good compression wrt WAV)? Or is it lossy (as per MP3)?

I am asking because I have been using line in from my Hi-Fi and recently it has started to break up. I found that it was set to automatic. Changing it to compressed removes the problem - I have not tried using uncompressed yet.


The line-in takes an analog signal and digitizes it for streaming. The Uncompressed setting is lossless, the Compressed setting is lossy. The Auto setting attempts to analyze your wireless signal and use the most optimum setting (Uncompressed for a strong wireless signal, Compressed for poorer wireless). If your stream is breaking up, Compressed is the correct setting. You can attempt to beef up your wireless signal by placing a Bridge midway between the Sonos device with the line-in and the next closest device.
Do we know if it is lossless (as per FLAC which achieves quite good compression wrt WAV)? Or is it lossy (as per MP3)?

I am asking because I have been using line in from my Hi-Fi and recently it has started to break up. I found that it was set to automatic. Changing it to compressed removes the problem - I have not tried using uncompressed yet.

I believe the Uncompressed option is stereo PCM, i.e. effectively WAV.

Changing the setting to Compressed may resolve your problems, but at the expense of quality and a slight delay.

There is however a halfway option which you might like to try. Leave the compression setting on Uncompressed but set the Line-In source to AirPlay Device. This will increase the amount of buffering in the network and may help it ride out the glitches you've been experiencing.

After selecting AirPlay Device you can go back and change the Line-In name and source level to suit.
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Roughly what I thought, though I am surprised they didn't offer a lossless compression (as standard) to reduce traffic but not quality. Any idea what algorithm they use? Whatever it is it must be pretty good as I can't really tell.

I don't think automatic works very well though as it doesn't seem to learn after it starts to break up.
@ratty, you freakin' rock!!! I have struggled with droputs while listening to my phono line in for several years. After many, many hours troubleshooting on the phone with Sonos techs, replacing my bridge with the new more expensive one (name escapes me at the moment), etc. it still was not resolved. I has resigned myself to the fact that I would have to listen to phono compressed (which of course the Sonos tech assured me there was no degradation in sound quality, though I could tell there was).

Then, tonight I chose to search this topic again and low and behold found this thread. Tried ratty's solution above and it worked! I am now listening to Uncompressed phono line in and it sounds phenomenal! No dropouts (knock wood).

Thank you very much!!! The power of social at work.

Sonos, I recommend you update your knowledge base with the above solution as I have seen many threads over time from users who were frustrated with the dropouts on their phono line in...
I'm in the same boat as Chris & Amy, I've been searching for a resolution to this problem for about a year, never found this thread before. Ratty's solution is working as far as I can tell, though it's only been a few minutes, the change was pretty dramatic. Side note: I had to stop the Line-In source and start it again. Would agree that this deserves a permanent home where it can be found easier by support and customers!

Thanks Ratty!
Sorry, go too excited and forgot to check the delay vs video. So if you're like me and wanted this to resolve line in from your TV/Home Theatre on your stereo paired Sonos, there will probably be too much of a delay from the Video. The delay is much less than if compression is turned on, but still enough to drive you mad. Connecting via cable seems to do the trick.

Thanks anyway, Ratty. seems that this would be a fine workaround for any line-in source that doesn't have video matched to it.
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I had similar problems with monitoring my Apple TV audio through my Play 5 and Play 1 stereo pair. My Apple TV is connected to my Vizio TV via HDMI (ARC). My TV's speakers are turned off and the audio line out from the TV is connected to the line input of the Play 5 speaker that sits under my media center and TV.

This setup has worked flawlessly as long as I'm just using the Play 5 speaker alone. However, whenever I would use room grouping to loop in my Play 1s together with the Play 5 audio, I experienced all manner of audio dropouts on the Play 1s (the Play 5 never stuttered a bit)

I stumbled on the following solution and now have flawless playback on all Room groupings of my Sonos speakers when listening to audio from my Apple TV:

1) I connected my Play 5 directly to my router (wired vs wireless - I found wired to be better)

2) I set my Sonos compression to "Automatic" - it had been on "Uncompressed" when I was experiencing the audio dropouts.

The above two tweaks have resolved my issues and the video and audio are in sync.

Note: This method does not require you to enable the "Airplay Device" option which displays lip sync delay.
[quote=ratty]Do we know if it is lossless (as per FLAC which achieves quite good compression wrt WAV)? Or is it lossy (as per MP3)?

I am asking because I have been using line in from my Hi-Fi and recently it has started to break up. I found that it was set to automatic. Changing it to compressed removes the problem - I have not tried using uncompressed yet.

I believe the Uncompressed option is stereo PCM, i.e. effectively WAV.

Changing the setting to Compressed may resolve your problems, but at the expense of quality and a slight delay.

There is however a halfway option which you might like to try. Leave the compression setting on Uncompressed but set the Line-In source to AirPlay Device. This will increase the amount of buffering in the network and may help it ride out the glitches you've been experiencing.

After selecting AirPlay Device you can go back and change the Line-In name and source level to suit.
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Can't believe 5 years on and this is the only fix for drop outs when using the connect. Thanks for posting all those years ago. Worked great!

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