Something strange (and worrying) in the Winamp 2 plugin.

Brief description of problem:
Very sharp stabs of metallic-sounding noise. It sounds very much like a warped sibliant. At normal to high listening levels using headphones it is loud and unpleasant enough to make me fear for my hearing. Winamp's built-in visualization reacts to the noise, causing a couple of the bars to the right of the spectrum analyzer to jump at least two thirds of the way up.

When it occurs:
The problem only occurs when using the Winamp progression slider immediately after the track begins to play. At first I thought it was random, but I have since learned to provoke it on at least two different files. It seems to be directly related to 1) how "far" you seek" and 2) the program material. It always occurs on the same exact spot, after seeking to approximately the same spot.

Example:
On David Bowie's track "Sunday", first off the album "Heathen": if I grab the slider within the first five seconds of playback, and seek to at least 0:45, the problem will invariably occur at 0:58. Same exact spot; always the "L" in the line that goes "Look for the...". Seeking further into the song, and then seeking back to about 0:45-0:55 will produce the same results.

The other track is completely different material, Schubert's "Death and the Maiden", a Naxos recording from 1992. The problem does not occur at the same time, but can be provoked in a similar fashion.

Details:
I use Winamp 2.81, with in_mpc versions 0.96 and 0.97f. They behave identically. I use Clip Protect and ReplayGain in title mode, with Dithering enabled. No EQ, and no DSP plugins (although I've verified that the problem persists with DSP plugins running). The tracks in question were encoded using 1.14 with --xtreme and --xlevel. I've had the problem occur on files produced with earlier encoders as well, but haven't been able to verify them yet.

/ Uosdwis

That was supposedly fixed since version 0.96, could you email me a file where this occurs in 0.97f to cse@sci.fi.

I can only comfirm it happened to me too. plugin 0.97f
I'm afraid I can't give any useful info for debugging
it looked random to me, and happend only a couple of times so I didn't care.
I actually thought it was my hardware playing tricks or something. It felt like my laptop drive interfering with emulated "soundcard"... I don't know...

P.S. Heh, I don't care anyway. When foobar gets buttons and becomes stable I'll probably switch to it from winamp.

I sent Case the file mentioned in my first post. Here's his reply:



I later found another track where the error is easy to reproduce - another Schubert, actually. This time the problem is really awful, much more obvious and much worse than on the Bowie track, adding of a chirping kind of noise. Plugin used is 0.97f. This is what I was talking about when I said I fear for my hearing. One burst like this at high level and my ear seriously hurts.

Case: I can send you the track, if you want. But it's 11 MB on my drive, so it'll be at least 15 in your inbox.

Is this problem somehow SV7-related (meaning it will be gone in SV8)? And what's the solution for now?

/ Uosdwis

Edit: Oh yeah, is this a Winamp problem or does it happen with any realtime decoder like Foobar etc?

Try 0.97g first, I allow fast seeking much later in the file now.


It started at some point after 1.0 encoder, I don't really know why. It's decoding issue when using tricks to seek faster. I never got any guesses from Klemm why this happens.


It should happen with all decoders that are based on Winamp plugin sources, so foobar should be affected too.

I spent a while with 0.97g trying to reproduce the error on the files I mentioned. I had no luck. It appears to be completely gone. Good work, Case!

I urge everyone to upgrade. Although you may not have as sensitive hearing as I do (I suffer from an old hearing damage that has lowered my tolerance), at its nastiest and under unfortunate circumstances, the error could potentially do some damage to your hearing - or even your equipment. Unlikely, I admit, but why take the chance?

/ Uosdwis