SoX is a cross-platform command line utility that can convert various formats of computer audio files into other formats. It can also apply various effects to these sound files, and, as an added bonus, SoX can play and record audio files on most platforms.
Some players display, or play files, in the order that the file was originally copied to a USB drive or stick. YAFS (Yet Another FAT Sorter) allows the order to be changed to whatever you prefer. YAFS is a multi-platform, open source, freeware, command line utility with a GUI (Graphical User Interface).
This software simultaneously displays instantaneous peaks, VU, PPM, CBS Technology Center loudness, and ITU BS.1770 loudness. All meters include peak-hold functionality that makes the peak indications of the meters easy to see.
The software accepts two-channel stereo inputs. The VU and PPM meters are split to indicate the left and right channels. The PPM meter also displays the instantaneous peak values of the L and R digital samples. ~ Hydrogen Audio
Source: ORBAN Loudness Meter
REW is free room acoustics analysis software for measuring and analyzing room and loudspeaker responses. The audio analysis features of REW help you optimize the acoustics of your listening room, studio or home theater and find the best locations for your speakers, subwoofers and listening position.
Quod Libet is a GTK+-based audio player written in Python, using the Mutagen tagging library. It’s designed around the idea that you know how to organize your music better than we do. It lets you make playlists based on regular expressions (don’t worry, regular searches work too). It lets you display and edit any tags you want in the file, for all the file formats it supports.
Unlike some, Quod Libet will scale to libraries with tens of thousands of songs. It also supports most of the features you’d expect from a modern media player: Unicode support, advanced tag editing, ReplayGain, podcasts & Internet radio, album art support and all major audio formats – see the screenshots.
Ex Falso is a program that uses the same tag editing backend as Quod Libet, but isn’t connected to an audio player. If you’re perfectly happy with your favorite player and just want something that can handle tagging, Ex Falso is for you.
Providing hard-to-find pieces of software since 2001
Repository of open audio CODECs, compiled LAME binaries and freeware utilities.
Mp3tag is a powerful and easy-to-use tool used to edit the metadata of audio files. It supports batch tag-editing of ID3v1, ID3v2.3, ID3v2.4, iTunes MP4, WMA, Vorbis Comments and APE tags for multiple files at once, covering a variety of audio formats.
You can rename files based on tag information, replace characters or words in tags and filenames, import / export tag information, create playlists and more.