FS#8106 - Clipping/clicking with Crossfeed+Dithering
Attached to Project:
Rockbox
Opened by Philip Barton (audiophyl) - Wednesday, 07 November 2007, 07:36 GMT
Last edited by Thom Johansen (preglow) - Tuesday, 04 December 2007, 17:00 GMT
Opened by Philip Barton (audiophyl) - Wednesday, 07 November 2007, 07:36 GMT
Last edited by Thom Johansen (preglow) - Tuesday, 04 December 2007, 17:00 GMT
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DetailsOn my X5, the newest builds (post-metadata-on-buffer) will click/clip the audio if Crossfeed and Dithering are both enabled. This is only audible if the audio is mastered *loud* (metal: yes, NPR.org podcasts: no).
If Crossfeed or Dithering are disabled/enabled exclusively, the problem does not exist. For testing purposes (build 15510): 1) all settings were reset to default 2) Crossfeed was enabled 3) Dithering was enabled |
This task depends upon
Closed by Thom Johansen (preglow)
Tuesday, 04 December 2007, 17:00 GMT
Reason for closing: Fixed
Additional comments about closing: Should be fixed now, please open a new bug report if it isn't.
Tuesday, 04 December 2007, 17:00 GMT
Reason for closing: Fixed
Additional comments about closing: Should be fixed now, please open a new bug report if it isn't.
Platform: H320
Once again, the problem only surfaces when Crossfeed and Dithering are both enabled. If I am just using Crossfeed or just using Dithering, there is no clicking/clipping.
What is the worst-case scenario for output volume with Crossfeed + Dithering? 0dbFS? Even -0.1 dbFS can clip...
-Philip
-Philip
I'm too lazy to make a shorter clip (sorry!), so I've just uploaded a song:
http://people.cs.und.edu/~pbarton/problem_file.mp3
I only have the X5 to test this on. Once again, this occurs even after a full settings reset and only with Crossfeed and Dithering *both* enabled. The clipping/clicking is audible at any volume level.
I hope this helps in tracking down the cause!
-Philip
Zooming in on the wave-form should reveal that 0dBFS is neither hit nor sustained with enough frequency to cause the amount of clipping/clicking audible during playback. Still, any clipping visible in the file is not audible *until* Crossfeed & Dithering are enabled simultaneously. That tells me the audio is being altered in manner which is cause for (some, possibly small) concern.
I'm presently listening to the second newest Dream Theater album, and am hearing more of the same. The audio is normalized to 98% and the clipping is still audible. I'd have uploaded one of these songs instead, but they tend to be very long.
-Philip
I can live without Dithering, but shrugging off the potential problems doesn't seem like a long-term solution. I really wish I understood digital audio enough to sort this out on my own, but alas I am a lowly CS undergrad with not much useful experience in programming. :)
Also, the problem does go away if Crossfeed's direct gain is lowered to the lowest possible setting of -6.0dB (-4.0dB for Dream Theater). It still sounds like there is something odd happening with the audio at peaks which doesn't happen without Crossfeed + Dithering, though.
Wish I could be of more help.
-Philip
This is all quite besides the point, though, as when I enable dithering I get nasty overflow clicks, which I assume are what you're talking about. I'll check this out.