ReplayGain and Winamp
To apply WA's ReplayGain (RG) to your music files, right-click one or more selected songs in the Media Library or Playlist and select 'Calculate Replay Gain' via the 'Send To' menu. Some Winamp skins (user interfaces) provide additional ways to select a RG calculation. The calculated RG values are stored in special file tags. These tags can only be understood by music players that recognize this particular implementation. The actual audio data is unchanged. The data in these tags is used by WA to control the overall volume as it plays the song. Offically supported file formats are MP3, WMA, WMV, AAC, MP4, M4A, OGG & FLAC. The wavpack format (WV) is also supported if the wavpack decoder (included in the Winamp Essentials Package) is installed.
The RG calculation determines the peak value detected in each song. The peak value is used along with the track (song) and album adjustment values for a particular target dB level that will control the overall volume without causing clipping. The relatively low overall target dB level used is not published and can not be changed. The final overall volume may be lower than it needs to be, but this 'safe' dB level is easily countered by raising your sound device's master volume control and/or applying the Replay Gain Preamp (explained below).
Album value calculations seek to maintain any relative volume level differences between songs, as they are on the real album. To use this correctly, only select the songs that are from the same album when you do the RG calculation and be sure the album tag in these files is correct. If a file's album tag is empty, the album value is not calculated but the track value is. The track values are always calculated even if there are no tags in the files.
Selecting 'Save as Album' when you save the RG calculation results saves both the album and track values. That way you can use either one when you want to. WA dev's recommended preference is to use 'Save as Album'. Selecting 'Save Track data' when you save the RG calculation results only saves the track values. I recommend using this option if you have included songs from different albums in the same RG calculation. You can redo the RG calculations at any time (if you decide to group song selections by album and add their RG album values later).
WA's use of these RG tags is enabled/disabled via the General Preferences - Playback - Replay Gain options. The other 8 options on this General Preferences page are;
1) Amplification Mode:
Default selection is 'Apply Gain / Prevent Clipping' (recommended by WA devs). This will level out the overall volume and prevent distortion. Three other choices are available: Apply Gain, Prevent Clipping, and Normalize. These are sub-optimal ways to use RG. Applying gain alone may cause clipping. Preventing clipping alone will not level out the overall volume. Normalizing will apply a constant amount of 'correction' to reach the target dB level and may cause clipping. Normal RG uses varying amounts of 'correction' to reach the target dB level.
2) Preferred Source:
Choose between 'Track' (default, all songs play at close to the same level even if they are from the same album) or 'Album' (songs from the same album will maintain their relative volume differences, if any).
3) Disable if preferred source not available:
Disables RG if e.g. 'Album' source is selected but only 'Track' tags are available.
4) Adjustment for files without RG:
Pre-amp selection applied to all files without
RG tags (default value is -6.0 dB). -6.0 dB was chosen as an average across a broad range of music and deemed appropriate for the target dB level that WA's RG uses. I recommend changing this to 0 dB and adjusting it as needed when playing songs with RG tags mixed with those without RG tags.
5) Replay Gain Preamp:
Pre-amp selection to adjust the global gain for all files with or without
RG tags (default value is 0 dB). This gain is not
taken into account by the RG calculations. It may be useful when playing streaming media that is very soft or very loud (you still need to be ready to adjust volume manually). This gain can also be useful if you feel that WA's RG overall volume level is too soft. Use this preamp (and the previous option #4) with care, it could work against what you're trying to accomplish with RG.
6) Ask before writing Replay Gain to analyzed files:
When enabled, the RG calculation results window will appear at the end of the calculation. When disabled, track and album (if applicable) values will be saved automatically without prompting. WA always displays a window that shows the progress of the calculations.
7) ---Ask after each album is scanned:
Prompts to save values after each file is scanned.
8) ---Ask after all files are scanned:
Prompts to save values after all files are scanned.
Within the media library's CD ripping options is another RG related option, "Automatically calculate Replay Gain". This option enables/disables the automatic calculation and application of RG values to ripped files. This is a hidden process which occurs at the end of each individual track. The default behavior is to apply album and track tags. Note that enabling this option may considerably slow down the overall ripping process.
Undo (returning songs to their original volume levels) is simple, just disable WA's use of the RG tags. Alternatively, the WA tag editor may be used to delete the RG tags from files that use the vorbis tagging standard (e.g. flac). A 3rd party tagger must be used to delete RG tags from files that use other tagging standards (e.g. id3 in mp3s) and may also be used to delete vorbis RG tags.
Still using mp3s? Yes, move on the Part 3. No, go apply WA's RG and stop jumping for the volume control.