Naud is a bash script for normalizing audio files using the normalize-audio utility. It is specifically aimed at mp3, ogg and flac files.
Download it here.
naud - adjust levels of flac, mp3 or ogg files by decoding to wav, running them through normalize-audio(1) and then re-encoding.
naud [OPTION1]... [FILE1]... [OPTION2]... [FILE2]...
Adjust levels of flac, mp3 or ogg files by encoding to wav, running them through normalize-audio and then re-encoding. This requires as much extra disk space as the sum of all flac, mp3 or ogg files to be decoded. Unless the encoded file type is different from the input file type the original file will be overwritten.
A file is any parameter not beginning with a "-", for naud a file may also be a directory. An option is any parameter beginning with "-". Options, when set, will affect any later file or directory specified. Any option may be set to a different value later on after which the new value is used for all later files.
-o TARGET
TARGET is one of "same", "ogg", "vorbis", "mp3", or "flac". "vorbis" is a synonym for "ogg". The default for this option is "same". When set to "same" this option causes naud to re-encode the files using their original encoding type and will overwrite the original file. Any other option forces re-encoding to the type given in the option. This is mainly used for re-encoding flac files into another type such as mp3 or ogg. It may also be useful if you own an old or badly designed audio player which can play only mp3 files although, generally, it is not a good idea to encode mp3 to ogg or vice-versa. There is little point in re-encoding both mp3 and ogg files to flac.
-t DIRECTORY
Because naud can use a lot of temporary space this option allows you to specify the temporary directory to use. Naud will create temporary directories under DIRECTORY for its use. The default for this option is the value of the environmental variable TMP.
The following options are passed through to normalize-audio:
Although -q and -v are likely to be of little use as naud captures all the output of normalize-audio.
Because naud allows options to span multiple files this presents a problem if you want to turn off an option. In this case all the above options which are passed to normalize-audio can be switched off by adding a "-" as a suffix. Thus to switch off "-a 2" you would use "-a-", to switch off -n you would use "-n-", etc. It is permitted to use an option that has a value mulitple times, in this case the value used will change to the latest. Please note that long options for mormalize-audio (e.g. --clipping) are not permitted.
If a single file is specified then naud will normalize that file. File lists are allowed thus "*" will expand to all files in the current directory and naud will treat this as a list of single files. Naud will ignore all non-flac, non-mp3 and non-ogg files.
If a directory is specified then naud will batch normalize all audio files in that directory. The difference between this and normalizing a single file is that during batch normalization the volume of the files relative to each other remains unaffected. This is useful when normalizing whole albums. The assumption here is that whole albums will reside in their own unique directory. In practice this is not usually a problem.
Naud will preserve the following audio tags:
For files that use lossy compression (mp3 and ogg) naud will attempt as best it can to re-create the quality of the original file. This is a tricky subject and involves some magical incantations. The natures of mp3 and ogg are such that it is impossible to make an exact re-creation of the original. Naud will do its best to keep the quality of the original file without overdoing it and making files that are over-large. There are a number of heuristics that are used for mp3: for very high bit rate files a constant bit rate encoding will be used, for very low bit rate files then average bit rate encoding will be used, for the more common cases naud will encode mp3 files using a variable bit rate scheme. When encoding lossy files from flac files the defaults used are "-V 0" to lame for mp3 and "-q 6" to oggenc for ogg. These values are set near the top of the naud script and are therefore easily changed, take a look at the lame and oggenc man pages to see what these values mean.
Naud is a bash script and relies on other programs for normalizing audio files. The dependencies are:
