Note: This plug-in does not change the audio in any way and does not write metadata. It just calculates the Track Gain level for the selected audio and displays it. [UPDATE: The new version includes a "Normalize" option that does change the audio]
The gain level indicated by this plug-in may be slightly different to other implementations of ReplayGain due to minor differences between the Loudness Filter used in this plug-in and that specified in the ReplayGain 1.0 specification. However it should be sufficiently accurate to be useful.
How to install:
Installation is the same as for any other Nyquist plug-in.
Place the ReplayGain.ny file in the Plug-Ins folder inside the Audacity installation folder. On Windows computers, this is usually under "Program Files". On Mac OS X, it is usually under "Applications". On Linux it is often easiest to create a plug-ins folder ~/.audacity-files/plug-ins/
Restart Audacity, then the ReplayGain Plug-ins will appear underneath the divider in the "Analyze" menu.
Purpose of this plug-in:
When making compilation CDs is is often beneficial to adjust the volume level of individual tracks so that each track will play at a similar volume on the CD. The ReplayGain level that is calculated by this plug-in can act as a guide to how much amplification needs to be applied to each track so that they will have (approximately) equal loudness.
How to use:
- Import all of the tracks for the compilation into Audacity.
- Select the first track and apply the ReplayGain effect.
- Open the Amplify effect and enter the ReplayGain amount in the "Amplification (dB)" control, then apply to the selected track.
- Repeat steps 2 and 3 to each track.
- Review each track to ensure that the relative loudness is roughly equal for each track and adjust if necessary.
- Select all of the tracks (Ctrl+A) and apply the Amplification effect with the default settings.
The way that human hearing detects loudness is subjective, extremely complex and context sensitive, so as with all current algorithms for equal volume playback, ReplayGain can only offer a reasonable guess as to the required gain to achieve equal loudness. Because of this limitation it is advisable to listen to the tracks before exporting the files and committing to CD.
The track sample rate must be at least 44100. This is the minimum sample rate to support the full audio frequency range.
Not all tracks are supposed to be the same loudness. If your compilation includes a Thrash Metal track followed by a gentle lullaby, the second track should probably be quieter than the first. The plug-in is unaware of the emotive connotation of the music, so this decision must be made manually and appropriate action taken.
ReplayGain should be reasonably accurate at achieving equal loudness within a specific genre of music, but is less accurate when comparing music of different genres.
Released under terms of the GNU General Public License version 2:
Request from the author:
Please give feedback!
If you find this plug-in useful, please let me know.
If you have questions about how to use it, please ask.
If you have suggestions for improvements, please make them here.
Any other comments, please post.
Analyze plug-in (OLD VERSION): UPDATE:
NEW VERSION This includes "Equal Loudness Normalizing" and will show up in the Effect menu as "ReplayGain".