Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.
Skype uses P2P (peer-to-peer) technology to provide voice- and video-based communication with other Internet users. The technology is extremely advanced, but easy to use. It features excellent sound quality, end-to-end encryption, and automatic negotiation of firewalls or routers. Among major features are SkypeOut and SkypeIn, adding the possibility to make low-cost calls to land line phones and having a fixed number to be able to receive calls from land line phones.
Linphone is an audio and video Internet phone with GTK+ and console interfaces. It uses the SIP protocol, and is compatible with most SIP clients and gateways. It can use various audio and video codecs such as Speex, GSM, G711, G722, ilbc, amr, Theora, H263-1998, MPEG4, H264, VP8, and snow.
The GNU Compact Disc Input and Control library encapsulates CD-ROM reading and control for applications wishing to be oblivious to the OS- and device-dependent properties of a CD-ROM. It provides an API for access to SCSI-MMC (multimedia commands) and support for CD image types like BIN/CUE, cdrdao's TOC, and Nero's NRG, which gives applications using the library the ability to read disc images as though they were CDs. ISO-9660 filesystem support is included, as are utility programs for displaying CD and CD-ROM drive information, reading the blocks of a CD, and extracting files from an ISO-9660 filesytem image. cdparanoia is also included.
GImageView is a GTK+ based image viewer. It supports tabbed browsing, thumbnail table views, directory tree views, drag and drop, reading the thumbnail cache of other famous image viewers, and a flexible user interface. It also support movies using the Xine library and MPlayer, and supports images in compressed archive formats like tar.gz, zip, and lha.
prokyon3 is a multithreaded music manager and tag editor. It can access MP3, Ogg, and FLAC files on hard disk, CDROM, SMB, and NFS. Files can be played using XMMS or other players. The file view is customizable and favorite artists are supported. prokyon3 also offers an editor for ID3 and Ogg tags and has been designed to support tagging large quantities of files.
Aqualung is an advanced music player originally targeted at the GNU/Linux operating system, and also running on FreeBSD, OpenBSD, and Microsoft Windows. It plays audio CDs, Internet radio streams, and podcasts as well as sound files in just about any audio format, and has the feature of inserting no gaps between adjacent tracks.
PyKaraoke is a karaoke player which supports the CDG (MP3+G, OGG+G), MIDI (.KAR, .MID), and MPEG formats. The project consists of a GUI frontend and separate pycdg, pykar, and pympg player modules. The GUI provides a full application frontend, with playlist functionality and a searchable database. The pycdg, pykar, and pympg modules can also be used as standalone command-line players or imported into any Python programs that would like CDG, MIDI/KAR, or MPEG playback.