• Status Closed
  • Percent Complete
  • Task Type Bugs
  • Category Drivers
  • Assigned To No-one
  • Operating System iPod 3G
  • Severity Low
  • Priority Very Low
  • Reported Version Release 3.8
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by yzflcyq - 2011-03-27
Last edited by saratoga - 2012-06-26

FS#12030 - Rockbox have the channel "left-side-right" when playing back

I’m using iPod Classic 3rd, 160G and my Rockbox is r29613 compiled by myself.
When I try to play music with it, I found that the sound come from the left of the headphone is actually the right channel, and likely the sound come from the right headphone is actually the left channel.
How could it happend?
I’ve tested some wav, ape, mp3, wv files and all of them appear the problem above.

Edit: Changed category to drivers.

Closed by  saratoga
2012-06-26 03:03
Reason for closing:  Fixed
Additional comments about closing:   Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407

Likely fixed in  FS#12519 .

MikeS commented on 2011-05-17 22:13

Depending on the audio codec setup, the i2s setup and whether or not it was addressed in the driver, channel swapping can happen. Sometimes one has to fight hard with the hardware to avoid or minimize it and seems to be more likely with the codecs in master mode and SoC in slave mode combined with not sending (or not being able to send) samples as single 32-bit words (L16+R16).

I'm not talking as an expert on the Classic 3G or saying this is definitively the reason, just experience I've had with others.

I tested OndaVX747 and it has the same problem.

Hi, I've got the iPod nano 2nd generation with 3.9 and can confirm this. Playing a file often starts with channels reversed. Unfortunately this is a show stopper since I need to know right from the start what channel the sound is coming from (I'm a musician and wanted to use RockBox on stage.)

MikeS commented on 2011-10-14 20:12

I'll stand by my earlier assessment that someone needs to fix the PCM drivers on whatever players have the problems to use packed samples (PP502x, Coldfire) or, if not possible, to somehow avoid any swapping issues (Gigabeat F/S). Nothing in the DSP path is at fault given that players that have PCM drivers crafted to avoid swapping (i.MX31) don't have the problem or at least they minimize the liklihood if that hardware if very stubborn (s3c2440).

Sometimes it takes a number of hours of messing around to find the right thing to do. Codec as master tends to produce the bug because the i2s interfaces sort of suck at knowing which channel is which in a FIFO.

I have no idea what it means that you're saying. Please excuse me asking: Can I do something about it? Or does this mean it should happen when I use the iPod OS as well?


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