Bugzilla – Bug 7947
Noise when Inverted polarity selected
Last modified: 2010-05-07 11:11:32 UTC
I'm having this problem with SC 7.0.1 - 19008, Firmware 37. I was also having the problem with the official 7.0 release. When "Polarity Inversion" is set to "Inverted polarity" under the player Audio settings, I get loud noise (crackling) at certain times playing certain tracks. This is 100% reproducible; when I have Inverted polarity selected, it happens 100% of the time when I get to certain points in certain tracks; when Normal polarity is selected it never happens.
David, have you tired reprogramming the Xilinx? You can do this by restarting the Transporter by holding the power button on the remote until the Transporter reboots and then holding the 1 button on the remote. The Transporter will display Programming Xilinx if you did it right. If this does not solve the problem would you attach one of the files that exhibit the problem to this bug? I was also curious how your Transporter is hooked up and what other equipment is connected to it.
Created attachment 3285 [details] test track Problem happens around 2:08 in with Inverted polarity engaged.
Yes, I've tried reprogramming the Xilinx. I've attached a track that exhibits the problem; the problem will happen about 2:08 in. The Transporter is connected via the balanced outs to a Jeff Rowland Concentra II, which is connected to ProAc D25s. FWIW, I am not alone in having this problem: http://forums.slimdevices.com/showpost.php?p=294596&postcount=12
Thanks for the file David. I hear it as well at about 2:14 into the track with inverted polarity. With normal polarity it plays fine. The flac seems fine and metaflac reports: sample_rate: 44100 Hz channels: 2 bits-per-sample: 16 total samples: 28412160 reference libFLAC 1.1.4 20070213 Sean, would this one be for you?
Confirmed bug is present in V.43 with this test track. Currently we are doing this inversion using a multiply, when gain is applied. I think it's probably doing the wrong thing when the input signal clips. Probably not too hard to fix, but will require rearranging some things and may have a small impact on CPU usage too. As such I am retargeting for 7.2. Alternate solution may be to do the inversion in the DAC instead.
Deferring to next release.
So, seeing as how Sean, ya know, doesn't work there anymore, any update on this bug? (I'd have thought that when someone leaves the company, any bugs that were assigned to him would get reassigned.)
7.4.x milestone is in the past
All new Squeezebox products are likely to be based on the SqueezePlay platform. We do not plan to implement any further enhancements to the ip3k firmware or which are targeted specifically at ip3k-based products.