The FAAC project includes the AAC encoder FAAC and decoder FAAD2. It supports several MPEG-4 object types (LC, Main, LTP, HE AAC, PS) and file formats (ADTS AAC, raw AAC, MP4), multichannel and gapless en/decoding as well as MP4 metadata tags. The codecs are compatible with standard-compliant audio applications using one or more of these profiles.
Speex is a patent-free compression format designed especially for speech. It is specialized for voice communications at low bit-rates in the 2-45 kbps range. Possible applications include Voice over IP (VoIP), Internet audio streaming, audio books, and archiving of speech data (e.g. voice mail).
msmtp is an SMTP client with a sendmail compatible interface. It can be used with Mutt and other MUAs. It forwards messages to an SMTP server which does the delivery. Features include various SMTP AUTH methods, TLS/SSL-encrypted connections (including support for client certificates), support for multiple accounts, DSN, and IPv6 support.
Find Duplicate Music Files detects music files that contain the same music, even if the files are differently named, and are in different formats such as MP3, OGG, WAV, WMA, M4A, and RealAudio and contain different or non-existent meta-information such as ID3 tags. The program operates on whole directories of music files, analyzes them, and outputs the filenames of pairs that seem similar, based on their audio fingerprint or perceptual hash.
Bogofilter is a Bayesian spam filter. In its normal mode of operation, it takes an email message or other text on standard input, does a statistical check against lists of "good" and "bad" words, and returns a status code indicating whether or not the message is spam. Bogofilter is designed with fast algorithms (including Berkeley DB system), coded directly in C, and tuned for speed, so it can be used for production by sites that process a lot of mail.
The procmail and formail mail processing package can be used to create mail-servers, mailing lists, sort your incoming mail into separate folders/files (real convenient when subscribing to one or more mailing lists or for prioritising your mail), preprocess your mail, start any programs upon mail arrival (e.g. to generate different chimes on your workstation for different types of mail) or selectively forward certain incoming mail automatically to someone.
MatrixSSL is an embedded SSL and TLS implementation designed for small footprint devices and applications requiring low overhead per connection. The library is less than 50K on disk with cipher suites. It includes SSL and TLS client and server support, session resumption, and implementations of RSA, AES, 3DES, ARC4, SHA1, and MD5. The source is well documented and contains portability layers for additional operating systems, cipher suites, and cryptography providers.
Streamripper records MP3, Ogg, AAC, and NSV audio and video files from Shoutcast and Icecast compatible streams. The streams can be recorded as a whole or in individual tracks. Streamripper also features a relay stream, which lets you listen or watch live from multiple clients while recording.