R128 is an industry standard algorithm for describing the loudness and dynamic range of audio. MC runs the R128 algorithm against files when doing Audio Analysis.
MC uses this analysis with its volume leveling feature, so if you don't have Volume Leveling turned on in DSP Studio, this is meaningless for you.
You can learn about how MC implements this feature at these two links, one of which has a link to the original R128 standard:
https://yabb.jriver.com/interact/index.php?topic=82025.0https://wiki.jriver.com/index.php/Dynamic_RangeOnce Audio Analysis is complete, MC writes the [Volume Level (R128)] field. You can show this field displayed in a column for any file, or see the field in the tag editor. MC uses the value of this field as input for the Volume Leveling function.
When Volume Leveling runs as playback commences, it will use whatever value is in this field. If you modify the field, you modify how Volume Leveling treats the file. (If you re-run Audio Analysis on the file, the calculated R128 value will be put back.)
A file that the R128 algorithm decided needed no adjustment would have a value in this field of 0.0.
If you decrease the value in this field, Volume Leveling will play the track quieter. A larger value will make the file sound louder. So if you reduce the value in the field by -1.5db, Volume Leveling will play the file 1.5db quieter. The whole file, not just the peaks.
Be warned that if this field is set to "Save in file tags" in MC settings, if you manipulate the field, the change will be written to the file. Other applications that read and honor the R128 tag will also adjust their playback of the file accordingly. Changing the value of the tag does not change the waveform of the file, only the R128 tag.
The reason you might want to manipulate this value is that R128 is not perfect. It emphasizes the main part, in terms of time, of the audio signal, and give less importance to short transient peaks. So a thing like a very loud gunshot will not have as much effect on an R128 analysis as on other algorithms. So if you think overall the volume is good, but wow that explosion was too loud, that is typical of R128. It's a good algorithm, but in my opinion works better for music than for movie soundtracks. Not many songs have gunshots. In such a case, reducing the field might give you results you prefer.
Some people might advise against doing this at all. But it is really appropriate behavior in only a small minority of cases. Like 1 or 2 out of a hundred. If you find you want to modify the volume of 20% or half of your files, you need to look at other ways to change volume in MC; there are many.
If you are interested in something that will address peak volume of transients, while leaving the rest of the soundtrack alone, Volume Leveling does not do that. You would need to look into Dynamic Range Compression.
I hope this helps...