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.
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.
Kid3 tagger can edit the ID3v1 tags and all ID3v2 frames in MP3 files and the tags in Ogg/Vorbis and FLAC files in an efficient way. It is easy to convert between ID3v1 and ID3v2, set the tags of multiple files to the same values and generate the tags from the file name or vice versa. Import is possible from freedb.org, MusicBrainz, and other sources of track data.
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.
RealPlayer plays streaming audio and video over the Internet in real-time. It plays RealAudio, RealVideo, MP3, 3GPP Video, Flash, SMIL 2.0, JPEG, GIF, PNG, RealPix, RealText, Ogg Vorbis, and Ogg Theora. It is available for Windows, Macintosh, Pocket PC, Nokia 9200 Series, Nokia 7650, Palm OS 5-based handhelds, Linux, Solaris, and many Unix variants.
XiX Music Player is a music player for MP3, Ogg, M4A, and FLAC files. It is easy to create and maintain your own playlists. There is an integrated lyric viewer that searches for the lyric of the song you are listening to. If the CD cover is found, it is also shown. You can also rip CD tracks to MP3 or FLAC. Listening to your favorite online radio stations is also possible. The focus is on having fast control of all your music.
Mixxx is software for DJs that provides everything needed to create live mixes. It allows you to beatmatch songs and crossfade them together, like you would with turntables and a mixer. It runs without any extra hardware, and offers a wide range of advanced features including comprehensive MIDI controller and vinyl control support. To obtain the lowest latency and highest responsiveness, it uses hardware video acceleration and takes advantage of multi-core CPUs.
SMPlayer is a complete media player for Windows and Linux. It uses MPlayer as a playback engine, which is capable of playing most video and audio formats (AVI, mkv, WMV, MP4, MPEG, etc.). It can also play and download YouTube videos. One of the most interesting features is that it remembers the settings of all files you play. So if you start to watch a movie but have to leave, when you open that movie again it will resume at the same point you left it, and with the same settings: audio track, subtitles, volume, etc.