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Q about an entire songs waveform - please help!
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| alanzo |
Say I'm working with a mono wave file of an entire song (I'm using mono to keep it simple)
when I open it up in a wave editor such as Soundforge.. what does it mean when there is to much UNDER the Inf.?
In other words... the wave data from below inf. is louder then the data above inf. what does this mean and how can I fix it?
please help! |
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| hey cheggy |
Got the same problem with one of my tracks. Reason has added these spikes to my kick loop that go way up but only on the left channel and only up the screen.
I've had problems with audio being stronger on one side before as well. Its not a panning issue is it? Or does it have something to do with negative phasing?
Thy? Where is your book of knowledge on this one. |
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| Red Room |
What you guy's are talking about is called DC offset. You can fix this with most audio editing software. Steinbergs Wavelab or Cooledit pro can fix it for sure. Here's a quote from Wavelab's help topics:
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Eliminate DC Offset
This function removes a problem that most often appears due to mismatches between various types of recording equipment.
It is recommended that this function is applied to complete files, since the problem is normally present throughout the entire recording.
A DC offset is when there is too large a DC (direct current) component in the signal. If the DC offset is really bad, it can be visible as the signal not being visually centered around the "zero level axis". However, the DC offset can be significant without actually being seen.
A DC offset is problematic for two reasons:
It affects where the zero crossings appear, which in turn affects the smoothness of splices between audio files.
Certain processing options do not give optimal results when performed on files with a DC offset.
Checking for and eliminating DC Offset
1. Select the wave you want to check and possibly fix.
2. Select "Eliminate DC Offset" from the Process menu.
A dialog appears stating the amount of DC offset.
3. Click OK or Cancel.
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I hope you're problem is solved now... |
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| alanzo |
well the problem was that the lead was to loud and over compressed which caused the DC offset.. So I fixed that and the two halfs of the channel seemed to be equal..
BUT.. now I know what DC offset is and can apply it to future productions if need be :) thanks! |
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| alanzo |
| I found what causes the DC offset.. a distortion FX did it.. it moves the wave of my lead up a bit.. best way to fix it from what I see is to move the DC offset by +/- 1,000 until it's about in the middle.. and then compress for loudness maximization.. is there a way to avoid getting a DC offset when using a distortion FX? |
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| Dj Thy |
Depends.
You got two kinds of distortion, if you look at it theoretically.
Distortion is nothing more than adding harmonics (higher frequencies that have a relationship with the fundamental frequencies. For example, 300, 450, 600 are all harmonics of 150 Hz).
Now you gotta make a difference between odd and even harmonics.
Let's take a simple 1000 Hz example. 2000 Hz, 4000 Hz, 6000 Hz are even harmonics, 3000 Hz, 5000 Hz, 7000 Hz, etc... are odd harmonics.
Take a simple sine wave. The sine wave doesn't have any harmonics, only the fundamental frequency. So, a 1000 Hz sine wave only has 1000 Hz, nothing else. I think you all know how a sine waveform looks (~).
Take a 1000 Hz square wave. Square waves are the extremes. It's the fundamental frequency of 1000 Hz + only odd harmonics (for a perfect square wave, which doesn't exist, the odd harmonics would extend infinitely. As it's impossible to make something like this with the actual technology, the harmonics decrease in amplitude the further you look). Likewise, you all know how the waveform of a squarewave looks (a perfect squarewave would have infinitely steep flanks, and absolutely flat tops and bottoms).
Do you hear the difference between the sine and squarewave? Right, the squarewave sounds very harsh.
That brings us to the first conclusion, adding odd harmonics makes the sound more harsh. Looking at the waveform, it either means making the flanks steeper, or flattening the curves. The more you do this, the more odd harmonics you add, the harsher it sounds, with the extreme case being the square wave. Think digital distortion here...
Now, when you add even harmonics, it sounds much more pleasant (think analog tape/tube distortion here : the so called "warmth" of tubes).
So second conclusion, adding even harmonics : more pleasant sounding than odd harmonics. BUT... How would you translate this in the waverform??? Well, that's basically the symetry of the waveform that changes, and mostly the symetry compared to the X-axis (so in short, if you take that 1000 Hz sine wave, and "transpose" it higher or lower compared to the x-axis, it would mean you add even harmonics). So with a lot of even harmonics, you would eventually get the same figure as with DC offset, taken as a snapshot.
The difference would be that DC offset would be throughout the waveform, as "normal" even harmonics would still return to zero once and a while. But it's rare you get significant DC offset by even harmonics (ie, a lot of distortion).
So, check your distortion settings if possible...
Usually, DC offset problems occur at the recording stage, and are best cured there (get the source right, remember), although in modern software, the detection algorhythms aren't too bad. |
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| alanzo |
damn.. are you a sound engineer or something?
I get a DC offset whether I use a "Digital Distortion" VST or a "Tube amp Distortion" VST.. granted they are both digital, but the Tube amp effect is supposed to emulate an analog effect.. |
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| Dj Thy |
Well, if you think a little bit about what I said, it should be clear.
Odd harmonics alone sound very harsh (like digital distortion you get when you go over 0 dBFS (Full scale = digital dB's).
And with very harsh I also mean, very unpleasant. So most distortion, even harsh hardcore metal distortion, still adds an amount of even harmonics (otherwise, I fail to see why you add something that makes it very unpleasant to listen to), to make it still sound nice.
It's all about the ratio of odd/even harmonics. If you got more even harmonics, it will sound "nicer, warmer" than if you had more odd harmonics.
But like I said, if you add an acceptable amount of distortion to a couple of instruments in the mix, it shouldn't be too bad. On the whole mix, you should be more careful (very small amounts). If you get unacceptable DC offsets, either you did something wrong, or the effect has a problem... |
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| alanzo |
| well in this situation.. the Distortion was only on the lead and it caused a considerable amount of DC offset were the lead was being played.. but I foun that if I render the lead and adjust the DC offset in the wave file the DC offset on the entire mix will be fine.. |
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