Does this look right?

Funky waveform

* Cross-posted to audiominds

After mixing down my song, I dumped it into Audacity. I kinda expected the top and bottoms (positive & negative?) of the display to look about the same. Clearly they are not. Is this abnormal?



I do have a sort of “pulsing” effect happening in the final mix that is NOT intentional, but I have yet to sort that out.

I believe it is called DC offset? Does audacity have a DC offset removal tool? I know when I used to use wavlab that was an option.
J

Looks like you’ve got a bunch of compression going on (giving you the pumping/pulsing) and it’s possible you may have something introducing some DC offset on one or more of your tracks.

dc offset ??
what is it ?

Quote (fleow @ Sep. 22 2005,13:55)
dc offset ??
what is it ?

The change in input voltage required to produce a zero output voltage when no signal is applied to an amplifier.


Can be introduced in the analog world by poorly designed pre-amp or amplifier circuits. Can be introduced in the digital world by lousy converters and/or poorly designed soundcard drivers. Yep. This is another place where driver software can muck things up. Include poorly written plugins in there too... (especially dynamics processors)

An audio signal is a varying AC waveform which should always cross zero at the same point for the entire waveform as the signal swings from positive to negative and back. Anything that cause a shift in "zero" is DC offset.

I think...

TG

n-Track’s EQ has a DC removal setting.

<!–QuoteBegin>

Quote
n-Track’s EQ has a DC removal setting.

How? Do you mean using High Pass?

Yes, it’s a preset.

DUH!!! I was thinking you meant the EQ that’s on each track by default. It’s actually in the big 20 band n-TRrack Parameteric EQ plug-in. Gotcha.

My bad! :)

Wouldn’t using that plug-in be masking the problem, i.e., you’re not supposed to be get waveforms like that when recording.

But an even larger problem is that you mixed your song way too “hot”. You should save the compression/limiting for the final mastering process.

I wouldn’t say masking the problem since it will be fixed in the mixdown, but it won’t fix the underlying cause, what ever that is. What ever is causing it needs to be isolated for sure.

I’ve seen plug-ins add DC offset to the resulting wave after destructive edits in a wave editor. Something I do semi-regularly will cause it and I have to undo, make a change, and redo to avoid it. Seems like it was related to normalizing or one of the many mastering plug-ins like endorphin…it might have been endorphin used inside Audition instead of in the master insert in n-Tracks…might not have been. That’s my first thought.

I dunno soul, it’s hard to tell if it’s too hot from the way it looks. Sometimes the style requires slamming it even more than that.

Quote (TomS @ Sep. 23 2005,16:15)
I dunno soul, it’s hard to tell if it’s too hot from the way it looks. Sometimes the style requires slamming it even more than that.

You’re kidding - right? You would very rarely want a waveform that has been limited like that when recording a track. This track has been either been severly limited or it’s severly clipped.

I would agree… reduce the input gain a bit. If there’s DC to remove after recording, so be it, but at least you’ll have the correct waveform. Once it’s been chopped you can’t get it back!

DSP

Thats the final mixdown. What your seeing is the sum of 20+ tracks. The only thing running on the master channel was Classic Series Master/Limiter. Rest assured that none of the input tracks are being limited.

I’m not sure what my problem was there, but the DC Offset thing seems to have corrected itself. That might be because I added some premastering compression before the limiter on the master channel.

It’s still a tad too “hot” … but I’ll fix that tonight.

Quote (phoo @ Sep. 23 2005,13:28)
I’ve seen plug-ins add DC offset to the resulting wave after destructive edits in a wave editor… Seems like it was related to normalizing or one of the many mastering plug-ins like endorphin…it might have been endorphin used inside Audition instead of in the master insert in n-Tracks…might not have been. That’s my first thought.

I’ve heard this before about Endorphin, I think it was Paul_R who told me. Where in the chain it was inserted I don’t know, though…
Either way Endorphin can give weird results if you don’t watch your settings. Attack & release especially (aren’t those the two faders on the lower left ? Going by memory here…) can do weird things to your material and you won’t need a wave editor to notice.
Quote (Mr Soul @ Sep. 23 2005,16:33)
Quote (TomS @ Sep. 23 2005,16:15)
I dunno soul, it's hard to tell if it's too hot from the way it looks. Sometimes the style requires slamming it even more than that.

You're kidding - right? You would very rarely want a waveform that has been limited like that when recording a track. This track has been either been severly limited or it's severly clipped.

Not kidding at all. Sometimes the song calls for it. Additionally, I don't see the time line on it, and if we are looking at 5 minutes worth, it could easly have a lot of dynamic range and look all squished. And it would not be clipped if the limiter kept it at or under zero. Pictures help but how can one judge based only on the picture?

You’re a wild & crazy guy Tom :laugh:

My bad - I didn’t see it was a final mix.