SpeexDSP is a DSP (Digital Signal Processing) library based on work from the speex codec.

The libtheora library implements the ogg theora video format, a fully open, non-proprietary, patent-and-royalty-free, general-purpose compressed video format.

Kate is an overlay codec, originally designed for karaoke and text, that can be multiplixed in Ogg. Text and images can be carried by a Kate stream, and animated. Most of the time, this would be multiplexed with audio/video to carry subtitles, song lyrics (with or without karaoke data), etc., but doesn't have to be.

Series of curves (splines, segments, etc.) may be attached to various properties (text position, font size, etc.) to create animated overlays. This allows scrolling or fading text to be defined. This can even be used to draw arbitrary shapes, so hand drawing can also be represented by a Kate stream.

Opus is a totally open, royalty-free, highly versatile audio codec. Opus is unmatched for interactive speech and music transmission over the Internet, but is also intended for storage and streaming applications. It is standardized by the Internet Engineering Task Force (IETF) as RFC 6716 which incorporated technology from Skype's SILK codec and Xiph.Org's CELT codec.

Ogg vorbis is a non-proprietary, patent-and-royalty-free, general-purpose compressed audio format.

The package vorbis-tools contains ogg123, an ogg vorbis command line audio player; oggenc, the ogg vorbis encoder; oggdec, a simple, portable command line decoder (to wav and raw); ogginfo, to obtain information (tags, bitrate, length, etc.) about an ogg vorbis file.

RNNoise is a noise suppression library based on a recurrent neural network. The algorithm is described in Jean-Marc Valin's paper A Hybrid DSP/Deep Learning Approach to Real-Time Full-Band Speech Enhancement.

Libao is a cross-platform audio library that allows programs to output audio using a simple API on a wide variety of platforms. It currently supports:

1. Null output (handy for testing without a sound device),

2. WAV files,

3. AU files,

4. RAW files,

5. OSS (Open Sound System, used on Linux and FreeBSD),

6. ALSA (Advanced Linux Sound Architecture),

7. aRts (Analog RealTime Synth, used by KDE),

8. PulseAudio (next generation GNOME sound server),

9. esd (EsounD or Enlightened Sound Daemon),

10. Mac OS X,

11. Windows (98 and later),

12. AIX,

13. Sun/NetBSD/OpenBSD,

14. IRIX,

15. NAS (Network Audio Server),

16. RoarAudio (Modern, multi-OS, networked Sound System),

17. OpenBSD's sndio.

Libshout is a library for communicating with and sending data to an icecast server. It handles the socket connection, the timing of the data, and prevents bad data from getting to the icecast server.

The libopusenc libraries provide a high-level API for encoding Opus files and streams.

Opus is a royalty-free, highly versatile audio codec. Opus-tools provide command line utilities for creating, inspecting and decoding .opus files.

GNU Speex is a patent-free audio compression codec specially designed for speech. It is well-adapted to internet applications, such as VoIP. It features compression of different bands in the same bitstream, intensity stereo encoding, and voice activity detection.

Expat is an XML parser library written in C. It is a stream-oriented parser in which an application registers handlers for things the parser might find in the XML document (like start tags).

The XML::Simple module provides a simple API layer on top of an underlying XML parsing module (either XML::Parser or one of the SAX2 parser modules).

Xlsx2csv is a program to convert Microsoft Excel 2007 XML (XLSX and XLSM) format spreadsheets into plaintext comma separated values (CSV) files. It is designed to be fast and to handle large input files.

The XML Security Library is a C library based on Libxml2. It supports XML security standards such as XML Signature, XML Encryption, Canonical XML (part of Libxml2) and Exclusive Canonical XML (part of Libxml2).

The conventional models for parsing XML are either DOM (a data structure representing the entire document tree is created) or SAX (callbacks are issued for each element in the XML).

XML grammar is recursive - so it's nice to be able to write recursive parsers for it. XML::Descent allows such parsers to be created.

This package provides the same API as XML::Simple but is based on XML::LibXML.

Libxml2 is the XML C parser and toolkit developed for the Gnome project (but it is usable outside of the Gnome platform).

This package provides a Python library to convert XML to OrderedDict.

This module aims to comply exactly to the https://www.w3.org/TR/xpath and yet allow extensions to be added in the form of functions. It also provides the command xpath.

Mini-XML is a small C library to read and write XML files and strings in UTF-8 and UTF-16 encoding.

XML::Compile can be used to translate a Perl data-structure into XML or XML into a Perl data-structure, both directions under rigid control by a schema.

This module provides an XPath engine, that can be re-used by other module/classes that implement trees. It is designed to be compatible with Class::XPath, ie it passes its tests if you replace Class::XPath by Tree::XPathEngine.

TinyXML is a small and simple XML parsing library for the C++ programming language.