FS#12835 - massiv random noise while playback mp3s with a clip+

Attached to Project: Rockbox
Opened by Wolfgang Dilg (rasferret) - Wednesday, 27 February 2013, 13:23 GMT
Task Type Bugs
Category Codecs
Status Unconfirmed
Assigned To No-one
Operating System Sansa AMSv2
Severity Low
Priority Normal
Reported Version Release 3.12
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No


When listing to a mp3 for some time there starts a massive random noise in the background. It will continue for some time when pausing or stopping playback and will also continue when starting another track.
I've noticed this when listening to a random list of mp3s of various sources and using speedup with 225% or 250%.

At the moment I'm using ee758c5 with my clip+.
This task depends upon

Comment by Michael Sevakis (MikeS) - Friday, 01 March 2013, 13:49 GMT
Do you mean that when playback is stopped or paused, it continues for a few seconds afterwords? Does it need to be MP3 and does it need timestretch to be active?
Comment by Wolfgang Dilg (rasferret) - Sunday, 03 March 2013, 18:42 GMT
I've investigated the problem a bit further. It starts sometime during playback and continues until shutdown, regardless of stopping or pausing the track. If it's happening only with mp3 and only with timestrech, I can't say at the moment.
Comment by Wolfgang Dilg (rasferret) - Monday, 04 March 2013, 07:01 GMT
The is not dependent on the codec. I've noticed the same behaviour with opus. The noise is not so random as i thought before. During playback it is pulsing with a speed that is dependent on the timestrech ratio. When playback stops or is paused the noise gets uniform.
Comment by Wolfgang Dilg (rasferret) - Monday, 04 March 2013, 11:37 GMT
It looks like I can't reproduce the problem with version ee758c5-130219 and default configuration with or without timestrech.
Comment by Michael Sevakis (MikeS) - Monday, 04 March 2013, 13:03 GMT
Having it continue after stop or pause makes me suspect that it's NOT in the codec but somewhere later in the PCM stream.

You mean it happens when not using the default configuration? If so, which audio effect or other setting making it happen?

Try to record it, also while paused and such. There should be no further sound 3 seconds after any sound has completed (playback, voice, keyclick) since playback does continue playing (what should be) silence for 3 seconds after the last sounds.
Comment by Wolfgang Dilg (rasferret) - Monday, 04 March 2013, 20:42 GMT
On my way back home form work I've reproduced the issue with version ee758c5-130219. Maybe I can record some of the noise. I've attached my config.cfg
Comment by Wolfgang Dilg (rasferret) - Wednesday, 20 March 2013, 21:52 GMT
Meanwhile I suspect some static discharges that were induced by the headphone cables when takeing of my jacket that may caused this issue. I can't reproduce this any more because my clip+ died earlier this week.
Comment by Wolfgang Dilg (rasferret) - Tuesday, 09 April 2013, 18:14 GMT
I've reproduced the issue with my new clip zip. This time I've managed to record the noise. Both files start with screen off and after about five seconds the screen gets turned on. The noise is independet of the volume (max or min).
Comment by Michael Sevakis (MikeS) - Tuesday, 09 April 2013, 18:47 GMT
I downloaded two that clips that were both silent. ??
Comment by Wolfgang Dilg (rasferret) - Tuesday, 09 April 2013, 20:46 GMT
Something went wrong with the recording level. :-(
I'll try to do another recording with proper settings when it happens again. But have to imagine the low noise and clicking in the first file at a much higher level.