Hydrogenaudio Knowledgebase - User contributions [en]

Apple iPod

2004-10-19T21:35:10Z

80.218.58.217:

The '''iPod''' is a [[hard disk drive|hard drive]]-based portable audio player from [[Apple Computer]], capable of playing [[MP3]], [[WAV]], [[Advanced Audio Coding|AAC]]/[[M4A]], [[AIFF]], and [[Apple Lossless]] [[file format]]s. In addition to its audio capabilities, the iPod may also be used as an external hard drive. Designed by [[Apple's Industrial Design Group]] under [[Jonathan Ive]], iPods are distinguished by their small size, simple [[user interface]] designed around a central scroll wheel, and [[IEEE 1394|FireWire]] or [[USB|USB 2.0]] connectivity. [[As of 2004|As of]] October [[2004]], the iPod was the most popular digital music player in the [[United States]], with 82% market sharefor HD-based players.

MPEG-4

2004-10-18T00:29:20Z

80.218.58.217:

'''MPEG-4''', introduced in [[1998]], is the [[name|designation]] for a group of [[audio]] and [[video]] [[coding]] [[standard|standards]] agreed upon by [[MPEG]] (Moving Picture Experts Group). MPEG-4 is primarily designed to handle low [[bit rate]] content, from 4800 bit/s to approximately 4 Mbit/s. The primary uses for the MPEG-4 standard are web ([[streaming media]]) and [[Compact disc|CD]] [[distribution]], conversational ([[videophone]]) uses, and [[broadcast]] [[television]].

MPEG-4 absorbs many of the features of [[MPEG-1]] and [[MPEG-2]], adding new features such as (extended) [[VRML]] support for 3D rendering, object-oriented composite files (including audio, video and VRML objects), support for [[Digital Rights Management]] and various types of interactivity.

Most of the features included in MPEG-4 are left to individual [[developer]]s to implement. This means that there are very few complete implementations of the MPEG-4 standard. Anticipating this, the developers added the concept of "Profiles," allowing various capabilities to be grouped together.

MPEG-4 consists of several standards—termed "Layers"—as follows.

*''Layer 1'' describes synchronization and multiplexing of video and audio.
*''Layer 2'' is a compression codec for video signals.
*''Layer 3'' is a compression codec for perceptual coding of audio signals.
*''Layer 4'' describes procedures for testing compliance.
*''Layer 5'' describes systems for Software simulation.
*''Layer 6'' describes Delivery Multimedia Integration Framework (DMIF).
*''Layer 10'' is an advanced codec for video signals also called [[H.264]].

The designated container for MPEG-4 content is [[MP4]], which was also defined within MPEG-4.

[[MPEG-7]] and [[MPEG-21]] serve other purposes.

====See====
* [[MPEG-4 Visual]]
* [[AAC]]
* [[MPEG-4 Systems]]
* http://forum.doom9.org/showthread.php?s=&threadid=73022

Theora

2004-10-18T00:28:23Z

80.218.58.217:

'''Theora''' is a [[video]] [[codec]] being developed by the [[Xiph.org Foundation]] as part of their [[Ogg]] project. Based upon On2 Technologies' [[VP3]] codec, and christened by On2 as the successor in VP3's lineage, Theora is targeted at competing with [[MPEG-4]] video (e.g., [[XviD]] and [[DivX]]), [[RealVideo]], [[Windows Media Video]], and similar lower-bitrate video compression schemes.

Theora is still in developmental stages with Xiph.org having made three alpha releases thus far.
* Alpha One was released on September 25, 2002
* Alpha Two was released half on December 16 and half on December 27, 2002
* Alpha Three was released on March 20, 2004

The first beta release Beta-1 is expected later in 2004. Theora is released under the terms of a [[BSD License|BSD-style license]].

While VP3 ''is'' patented technology, On2 has irrevocably given royalty-free license of the VP3 patents to all of humanity, enabling the public to utilize Theora and other VP3-derived codecs for any imaginable purpose.

In the Ogg multimedia framework, Theora provides a video layer, while [[Vorbis]] acts as the audio layer.

Theora is named for [[Theora Jones]], [[Edison Carter]]'s Controller on the [[Max Headroom]] television program.

Apple iPod

2004-10-18T00:20:40Z

80.218.58.217:

The '''iPod''' is a [[hard disk drive|hard drive]]-based portable audio player from [[Apple Computer]], capable of playing [[mp3|MP3]], [[WAV]], [[Advanced Audio Coding|AAC]]/[[M4A]], [[AIFF]], and [[Apple Lossless]] [[file format]]s. In addition to its audio capabilities, the iPod may also be used as an external hard drive. Designed by [[Apple's Industrial Design Group]] under [[Jonathan Ive]], iPods are distinguished by their small size, simple [[user interface]] designed around a central scroll wheel, and [[IEEE 1394|FireWire]] or [[USB|USB 2.0]] connectivity. [[As of 2004|As of]] October [[2004]], the iPod was the most popular digital music player in the [[United States]], with 82% market sharefor HD-based players.

X Multimedia System

2004-10-18T00:14:12Z

80.218.58.217:

The '''X Multimedia System''' ('''XMMS''') is a [[free software|free]] [[media player|multimedia player]], very similar to [[Winamp]], that runs on many [[Unix-like]] [[operating system]]s (including [[Linux]]). It supports skins that were made for Winamp. It was first released under the name X11Amp, with a license that did not provide any access to the program's [[source code]]. Nowadays, it is released under the [[GNU General Public License]].

=== Features ===

* Winamp 2 skin support

=== Supported formats ===

==== Playback ====

* [[MP3]], [[WAV]], [[AU]], [[Ogg Vorbis]], [[MP2]], Mod, XM, X3M, MED, IT, STM
* Audio CD

=== Supported languages ===

* English
=== Supported platforms ===

* Linux/BSD
* Mac OS X
* Solaris

=== External links ===

[http://www.xmms.org XMMS: Homepage]

[http://www.xmms.org/download.php XMMS: Download]

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