The idea of replaygain is quite simple: since volume of audio files could depend on how it has been encoded, replaygain imposes an audio level to smooth out the audio level of the audio files without physically changing the file itself (i.e. the changes made by replaygain are reversible).
Replaygain is better than normalization because replaygain computes not only the peak value of the track, but also the main audio level of the entire track. Thus, a quiet song with a very high peak will be at the same gain (or volume level) with a modern song which has a high level throughout.
In some cases, the value could be positive and create clipping (for quiet songs with high peaks) as a consequence, if you're listening to this kind of music, please use the Advanced limiter (which could do no harm in any case).
- Computing replaygain values
Select tracks without replaygain information and then use the contextual menu:
- Scan per file track gain
Will compute the track value for each track, but not the album value.
- Scan selection as single album
Will compute both the album and track values but the album value will be computed considering the selection as a single album
- Scan selection as albums
Will compute both the album and track values but the album value will be computed for each album.
- Remove replaygain info from files
Will delete all replaygain values from your files. It is quite useless as replaygain info do not alter our files in any way.
- Edit Replaygain info
It is not recommended to use this unless you have an hearable problem with your files linked to extreme values.
- Apply track Replaygain to MP3 data
Will use the track values computed to apply the gain to your audio file and consequently change them. It's not recommended as it will change your files and alter them while foobar2000 will do it by itself without having to change the files. Could be useful for files used on portable devices with no Replaygain support.
- Apply album Replaygain to MP3 data
Will use the album values computed to apply the gain to your audio file and as a consequenc change them. It's not recommended as it will change your files and alter them while foobar2000 will do it by itself without having to change the files. Could be useful for files used on portable devices with no Replaygain support.
- If replaygain values are already computed, it won't recompute them to earn time.
- Computing Replaygain values is quite slow: about 1 min for 20 tracks (generally, the scanner works at 78X). As a consequence, compute regurlarly Replaygain values to avoid long hours of computing. Moreover, computing those values uses quite a lot of your CPU resource.
- In 0.9 version, after its process, foobar will display the values computed and you will have to click on the update files button. Use it to see if extreme values are found for tracks/albums, it usually goes around -10dB to 0dB with peaks around 1.000/1.200. If anormal values are found, recompute or do not use Replaygain tags.
- Replaygain and Playback
- Source mode :
- Track: will use track values to process
- Album: will use album valuees to process
- Which mode should I use and why?
If you usually listen to single tracks, use track mode.
If you usually listen to complete albums (especially if you listen to classic music), the album mode is better. If you use track gain, you could hear the volume change during audience applause, or in the middle of an opera which has been split into different tracks. Using the album mode will change the volume only between albums, which is less annoying.
- none: won't use Replaygain
- apply gain: will apply the gain computed
- apply gain and prevent clipping from peak value: will apply the gain but considers the peak value to avoid clipping problems
- prevent clipping from peak value: will consider the peak value to avoid clipping
- Which mode should I use and why?
Use apply gain except if you listen to music with a moderate audio level and high peaks. (Classic music). As the gain is computed considering the average audio level, not the peaks. As a consequence clipping problems could occure for such tracks. But it is quite rare to have clipping problems because of replaygain.
- If you hear no sound at all or if you have to turn up your hardware volume, it could be because you are applying gain according to the peak value. If so, just choose "apply gain".
- Clipping problems can be solved with the advanced limiter.
The Preamp allows you to change the target level. By default it is 89dB. If you find it to low or to high, use the preamp to correct it.
- Files with RG info : For files with RG info, Keep it to 89dB, prefer changing the global volume level or your hardware volume than the target level.
- Files without RG info : It will allow you to apply a "fake" replaygain value for files without replaygain info. If you listen to modern music -7dB/-10dB value should be correct. If you listen to older music, keep the value a bit lower because the average level of recently released tracks are higher.
- Where are stored these values? Replaygain only calculates the average audio level of the track and the peak level (highest volum measured into the file). the results are saved by the software using replaygain info with different ways:
- stockpiled in metadata, when the audio format is optimized for replaygain (as mpc or lame mp3 (3.94 and above)) calculating these values at the encoding and saves them in the LAME tags
- inscription of the values in standardized tag fields linked to replaygain
- complete physical change of the file, depending on the calculated values (as did mp3gain, aacgain (in development) and wavegain)
- How does foobar compute replaygain values?
Foobar has an integrated replaygain scanner, which computes the audio level of files, correction values, an Peak. These values are written into the file tags or in its metadata if it is possible. But foobar will never change any bit of the audio stream. Replaygain with foobar won't alter your files more than the addition of a tag..
- The dB scale
dB gain=20log(I/I0) where I=final value and I0 the reference It's usually a negative value. -3db corresponds to dividing the output level by sqrt(2) this is a table for the correspondance between the percentage value and the dB value (after -60dB, it's nearly unhearable even if your hardware is put to max.)
in % in dB in % in dB 100 0 30 -10.4 90 -0.9 20 -14 80 -1.9 10 -20 70 -3.1 1 -40 60 -4.4 0.1 -60 50 -6 0.01 -80 40 -8 0.001 -100
August 30 2007 17:45:39.