FS#12417 - Audio crackling problem on Fuze v2

Attached to Project: Rockbox
Opened by Tucker Cane (problem_gash) - Wednesday, 30 November 2011, 04:34 GMT
Task Type Bugs
Category Music playback
Status Unconfirmed
Assigned To No-one
Operating System Sansa AMSv2
Severity Low
Priority Normal
Reported Version Release 3.9
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No


I have RockBox version 3.9 on my Sansa Fuze v2 and so far I love it, but I have one problem. On a few tracks in my library, when I play them, the first few minutes of the song will be strangely distorted. Most of them are songs where the music starts off in just one of the speakers before moving into the other one. There will be bursts of loud, crackly noise in the other speaker during these first few seconds (that seem to be in time with the music) and then it will fix itself and the rest of the song will play perfectly. When I boot the default Sandisk firmware the songs play perfect like they should, it is only in RockBox that this glitch happens. I've messed with the settings a bit and even reset them completely, but nothing has worked thus far.

Attached is one of the songs that this happens with, from about 2 seconds in to about 7 seconds in. Any help would be greatly appreciated. I really want to enjoy my music without that crap in it.
This task depends upon

Comment by Tucker Cane (problem_gash) - Wednesday, 30 November 2011, 04:45 GMT
It doesn't look like the file actually attached itself, but the song is "A Spanish Piece" by Pink Floyd if you want to take a look at it.
Comment by Ralf Karschnick (rok) - Friday, 17 February 2012, 14:58 GMT
I could reproduce this with my Sansa Fuze v2 with RockBock 3.10 installed. Pleas note, that this is a".wma file. The crackly noise did not reappear with my device after converting the file to mp3 and wav (usind CDeX)
Comment by Michael Sevakis (MikeS) - Saturday, 18 February 2012, 03:37 GMT
It sounds like a problem with the stereo decorrelation (at first guess). What pops up in the opposite channel from the one with audio is related to the signal and has the pitch of the the music.
Comment by Michael Sevakis (MikeS) - Saturday, 18 February 2012, 04:57 GMT
I checked on X5 (Coldfire) and the problem appears there too. VLC decodes it normally.
Comment by Ralf Karschnick (rok) - Monday, 20 February 2012, 08:14 GMT
In my humble Opition it is a problem with (Rockbox-) wma decoding. I do not know much about that stuff but it seems to work on non-Roxbox Players (Windows Media Player also worked well) and it does not seem to be fuze-spezific
Comment by MichaelGiacomelli (saratoga) - Monday, 30 July 2012, 04:49 GMT
Just took a quick look at the file, it does't even use mid/side stereo, just separate channels so its not a decorrelation problem. The static is also (nearly) spectrally white, and has no obvious correlation with whats happening in the other channel. It also last for exactly one MDCT block each time.

I guess i need to find time to go through the decoder process side by side with ffmpeg and figure out where the decoder state diverges from the correct values.