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Artifacts at the beginning of the file
xnor
post Feb 9 2012, 14:53
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Hello,

encoding the file linked below results in an artifact in the beginning of the mp3 (sounds like a click) using
$ lame --preset insane --noreplaygain B.wav
LAME 3.99.4 64bits (http://lame.sf.net)
...

B.wav
A.wav (mp3 converted to wav, edit: using lame --decode, which seems to be the cause of the problem)

Here's an overlay of the mp3 (red) and original wav (blue):


Any ideas why this is happening?

This post has been edited by xnor: Feb 9 2012, 18:22


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probedb
post Feb 9 2012, 15:51
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Almost sounds like it's encoding the header as audio?
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xnor
post Feb 9 2012, 16:09
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The artifact is not present in the mp3 itself. I traced the problem down to lame --decode. Decoding (mp3 -> wav) the file with fb2k doesn't result in that artifact in the beginning.

This post has been edited by xnor: Feb 9 2012, 16:23


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adamlau
post Feb 9 2012, 18:11
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You are a true audiophile, xnor! Hardcore, I have to be more like you. I'll check out the LAME bug tracker and build 3.99 through 3.99.3 later (I really need some sleep first), run a series of encodes/decodes, see if this issue is a regression, or a new bug.


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john33
post Feb 9 2012, 18:15
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It would seem this is a regression as I just decoded the mp3 with 3.98.4 and all was well. I'll check back and see where this may have occurred.


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xnor
post Feb 9 2012, 18:20
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@adamlau: Nope, being a software developer myself I just like seeing bugs fixed. wink.gif

@john33: Thanks for taking a look at this.

This post has been edited by xnor: Feb 9 2012, 18:20


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john33
post Feb 9 2012, 19:26
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Hopefully, Robert will pick up on this. There was quite a lot going on in the switch from mpglib to hiplib at this time making it a little difficult to track through but Robert, perhaps, could put his finger on this quite quickly. wink.gif

EDIT: I have emailed Robert to draw his attention to this. smile.gif

This post has been edited by john33: Feb 9 2012, 20:00


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robert
post Feb 11 2012, 12:08
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Thanks xnor, for finding this issue. It crept in early in 3.99 development. This will be fixed in official 3.99.5 soon.
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xnor
post Feb 28 2012, 12:09
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Thanks, that's good news.


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