Dithering Meters


Included in the dithering section are two meters. A DC offset meter lets you view the amount of DC reduction that is being performed on the program material, while a bit meter provides you a view of the bit activity of the digital signal.

Dithering

DC Offset Meter

When the DC Offset Filter is On, the DC Offset meter shows the level of the DC (in dB) that is being removed. You can right click on the meter to set options including turning it on or off, and enabling the peak hold or not.

Like other meters in Ozone, left-clicking on the DC offset meter will reset the peak hold and clear its history.

Bit Meter

This can be an invaluable resource for monitoring the digital activity of your program material, including viewing whether the full range of bits (dynamic range) is being used, the output word length, faulty A/D converters, sub-par plugin processing (detecting a plugin that's only processing at 16 bit, using fixed integer math, etc.), etc.

This meter monitors the state of bits in a digital signal.

The inner two columns show the real time activity of the bits of audio, for the left and right channels. The outer two columns remember the real time activity in a sort of "peak hold" way. If the inner columns toggle a bit  (i.e. "light up") the outer columns will show that bit as being used.

Bit Meter

This is not a level meter. Instead, it shows which bits are being used. If a bit is used (goes from 1 to 0 or vice versa) the position for that bit is lit.

The main use of the bit meter is to look for problems or discontinuities in the digital signal. Some examples of problems are shown below:

fig 1 24 bit  fig 2  16 bits  fig 3  Stuck Bit

  1. Headroom. In the first meter above (fig 1), upper bits aren't being used. You may have a 24 bit audio file, but aren't using all of the bits.

  2. In a more extreme case, you are only using 16 bits as shown by the second meter above (fig 2). Now if you're dithering to 16 bits, this is what you want to see. But if you're not dithering, this would suggest there is a problem somewhere. Either an A/D converter that is only putting out 16 bits, a plug-in that's truncating your signal down to 16 bits, etc.

  3. Stuck Bit. In the final case (fig 3), one bit in the middle of the signal isn't being exercised. Again, it could be a faulty A/D or bug with a software plug-in.

In general, you want to see activity on each of the bits (except the top one - see below for explanation). Meaning that over a period of a few seconds each of the bits in the outside columns should be lit. You should also click on the meter periodically to reset the peak hold of the outside columns, as something like DC offset would toggle a lower bit once (lighting the outside column) but would never toggle it after that since the bit is being held.

Of course, if you're dithering down, you only want to see 16, 12, or 8 bits lit (corresponding to the output bit depth of the dither)

Why the top bit will never light up

When samples are stored as a binary number, negative samples are specially encoded. Since the binary representation of negative numbers is not intuitive, Ozone takes the absolute value of each sample before plotting it on the bit meter. Since the most significant bit is only set when a sample is negative, this bit will never light up. We simply included the top bit as placeholder for completeness.