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'gurgling sound' on mp3 at song fade-out ?

post #1 of 5
Thread Starter 
this is strange, I'm only hearing this very recently (on almost all my old mp3 files).

as the song fades out, at the end, I hear a gurgling kind of noise. bubbling with some echo or bandpass filtering. hard to explain..

I'm sure its the encoding and not the rest of my system; in fact it may be the fact that I'm listening more and more carefully and on better equipment. but I'm just noticing this, now.

on flac files from the same cd source - I don't hear this problem. so it is in the mp3 encoding.

I've used lame but I mostly did the encoding with a quite expensive mp3 encoder (fraunhofer CLI encoder from 1998) I used to swear by that encoder and at 128k it did a much better job than any freeware version.

but now I'm not sure I can listen to those files anymore. that noise is heard anytime the volume drops fairly low and the average level is much lower than the rest of the song (ie, at start or end of songs). I use CBR on that fraun encoder, fwiw.

anyone else notice this? perhaps its well-known but I've just recently started to hear this. and its not limited to 128k; I have some 256k files that also have the gurgling effect on quiet passages.

I guess its no more mp3 for 'home listening'. on portables and in the car, its no problem; but for my 'good' home system its very noticeable.

(home system config: AMB y2 dac to AMB beta-22 3ch amp into hd-650 phones.)
post #2 of 5
What's the decoder you're using & have you tried mapping the waveout?
post #3 of 5
Thread Starter 
Quote:
Originally Posted by anetode View Post
What's the decoder you're using & have you tried mapping the waveout?
decoder doesn't seem to matter, I don't think. currently its the logitech squeezebox duet (spdif out) to my y2 dac. at least there's no worry about pc 'bit perfect' stuff there and I have volume control disabled on the logitech.

and by your 'mapping' question, I assume you assumed I was running windows?
post #4 of 5
Pardon the assumption

The decoder seems to be the most likely culprit, since you used CBR when encoding so the quiet passages weren't encoded in a lowered bitrate. Just for kicks I downloaded Fraunhoffer's codec & did some test track comparisons between that and lame. I can't tell the difference at 256 and I was unable to replicate the gurgling.
post #5 of 5
Thread Starter 
its possible the current fraun engine has improved in the last 10 or so years

I'll try to cut the last 5 seconds or so of a song to a file, for demo.

its like there is a squelch or thresholding thing going on; or even a 'gating' of the sound, trying to quantize to some very coarse average levels.

in all these years, I never noticed this before - that's what has me stunned. these files used to be just fine and now I'm hearing all these 'noises' in the encodes.
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