Dynamic Range Compression Meter
Measure the consequences of the Loudness War on your music files
DRC-Meter is a small software application that can be used to approximate the amount of
dynamic range compression
that has been applied to a digital audio file. It can hence be used to measure the effects of the
loudness war. It can
be used on any .mp3, .m4a, .wav, .aif, .flac or .ogg audio file. It will not affect the files in any way.
Note that dynamic range compression has nothing to do with data compression (such as mp3 encoding). If
you do not know the difference between the two, you probably do not need this tool.
Only compression of the microdynamics are measured. Compression of the macrodynamics (if any) are ignored.
A Java Runtime Environment (JRE) version 5 or greater.
the latest JRE can be downloaded for Windows or Linux at http://www.java.com (it's free!).
Mac OS X users should download it through software update. Note that it is installed by default starting from
Mac OS 10.5 and below.
DRC-Meter.zip (version 1.0.3, 1.68 Mb)
Graphical user interface
Double-click on DRC-Meter.jar to launch the application.
Just choose one or more audio files in the file dialog that opens and click ok. You can also choose folders, in
which case the application will recursively scan the folders for all supported audio files it can find. The results
of the analysis are displayed in the main window. Each audio file may require some seconds to some minutes to be
Command line interface
Lauch the application using
java -jar DRC-Meter.jar <file> [<file> ...]
where <file> is an audio file, or a folder containing audio files. The results of the analysis are
printed directly on the console.
Note: lauching the application from the command line without specifying any file will launch the graphical user
Understanding the results
The amount of dynamic range compression is given for each audio file by a number. The greater the number, the higher the dynamic range
compression (Note well: this measures the dynamic range compression and not the dynamic range).
Here's how I interpret the results (your interpretation
may will vary as dynamic range
compression is highly subjective):
Again this is about dynamic range compression and not about data compression.
- -1.5 - 1.0: likely not compressed, or only slightly compressed
- 1.0 - 2.5: weak compression
- 2.5 - 4.0: medium compression
- 4.0 - 5.5: strong compression
- 5.5 - 7.5: aggressive compression
The applications uses heuristics and produces an approximation of the dynamic range compression.
Never take any of the results firmly. Furthermore, DRC-Meter has a limited precision: when applied on several
audio files with exactly the same amount of
dynamic range compression, the results typically have a variation of +/- 1.0, and results with +/- 2.0 or more
occasionally happen. Hence if for example the average result of an album is greater by 3 or 4 than the average result of another
album, you can be pretty sure that the former has been more compressed than the later. However, if a single
song scores for example 1.5 more than another one, it may not mean anything at all.
More generally, the results will almost never magically tell you the exact parameters of the compressor plugins that was
used to compress the dynamics, and may even be quite far from the real values. The results are only comparable to what
you can infer by carefully looking at the audio file's waveform. If you know how effective it is to look at an
audio waveform, you know how effective DRC-Meter is. Note however that:
Note that DRC-Meter measures dynamic range compression. This is not the same as data compression such as
the bitrate of an mp3 file. It has in fact nothing to do with mp3 encoding in any way.
- DRC-Meter is not simply based on an estimation of the loundness. In fact it is (mostly) insensitive to the amplitude
of the audio file (as long as the peaks are above -16dB!)
- DRC-Meter is not a measure of the amount of dynamics. It measures the amount of compression of the dynamics.
This is important to understand. A file that scores high (highly compressed) can still have a lot of dynamics if it had
even more dynamics before the compression. Conversely, a file that scores low (weakly compressed) may have
few dyamics if it already had few dynamics before the compression. The two notions, dynamic range and dynamic range
compression are independant, although in practice, they are frequently correlated
- DRC-Meter is not just measuring the amount of clipping. It works with several kinds of dynamic range compression,
- DRC-meter only measures compression of the microdynamics, not of the macrodynamics
- DRC-meter uses heuristics and hence has a limited precision. While it constantly produces the same result for the same
audio file, results for different audio files that have been compressed by the same amount typically
exhibit variations of +/- 1, with occasional variations of +/- 2 or more.
- The precision gets quite low on short audio files (less than 1 minute).
- DRC-Meter works poorly with multi-band compression.
- Only .wav, .aif, .mp3, .m4a, .flac and .ogg files are supported.
- Error handling is poorly implemented.
- DRC-Meter only works with files sampled at 16bits, 44.1 kHz (CD quality). Other files may produce innacurate
results due to the use of a poor automatic resampling algorithm.
- When an audio file has both uncompressed and compressed parts, DRC-Meter tends to base the result only on the
part that is the most compressed, rather than on the average.
- DRC-meter only works when the dynamic range compression was the last processing step applied to the audio file (apart
from dithering). This is the case for almost all files ripped from a CD. Any further processing, even a simple frequency
equalizer, may drastically reduce the accuracy of the results (most of the time toward lower values).
Data compression (mp3, ogg) is usually safe as it only results in minor inaccuracies. Hence DRC-Meter should
still produce accurate results with files downloaded from iTunes or Amazon.
- A consequence of the previous limitation is that DRC-Meter is ineffective with recordings taken from analog
mediums (such as tapes or vinyls) as there is almost always some processing involved during playback with
- DRC-Meter measures the amount of dynamic range compression, not the amount of data compression
such as .mp3 bitrate.
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