Filename extension in the context of MPEG-4 Part 14

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. It was developed by Dolby, AT&T, Fraunhofer and Sony, originally as part of the MPEG-2 specification but later improved under MPEG-4. AAC was designed to be the successor of the MP3 format (MPEG-2 Audio Layer III) and generally achieves higher sound quality than MP3 at the same bit rate. AAC encoded audio files are typically packaged in an MP4 container most commonly using the filename extension .m4a.

The basic profile of AAC (both MPEG-4 and MPEG-2) is called AAC-LC (Low Complexity). It is widely supported in the industry and has been adopted as the default or standard audio format on products including Apple's iTunes Store, Nintendo's Wii, DSi and 3DS and Sony's PlayStation 3. It is also further supported on various other devices and software such as iPhone, iPod, PlayStation Portable and Vita, PlayStation 5, Android and older cell phones, digital audio players like Sony Walkman and SanDisk Clip, media players such as VLC, Winamp and Windows Media Player, various in-dash car audio systems, and is used on Spotify, Google Nest, Amazon Alexa. Apple Music, YouTube and also YouTube Music streaming services. AAC has been further extended into HE-AAC (High Efficiency, or AAC+), which improves efficiency over AAC-LC. Another variant is AAC-LD (Low Delay).

MP4 (formally MPEG-4 Part 14) is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images. Like most modern container formats, it allows streaming over the Internet. The only filename extension for MPEG-4 Part 14 files as defined by the specification is .mp4.

MPEG-4 Part 14 is a standard specified as a part of the MPEG-4 specifications, formally as ISO/IEC 14496-14:2003. Unlike the audio-only compression formats MP3 and MP2, MP4 is a container format that can hold various types of media from various codecs. During the 2000s, portable media players were sometimes erroneously advertised as "MP4 players", even if they may play a different format like AMV video and not necessarily the MPEG-4 Part 14 format.

Audio Video Interleave (also Audio Video Interleaved and known by its initials and filename extension AVI, usually pronounced /ˌeɪ.viːˈaɪ/) is a proprietary multimedia container format and Windows standard introduced by Microsoft in November 1992 as part of its Video for Windows software. AVI files can contain both audio and video data in an uncompressed file container that allows synchronous audio-with-video playback.

Like the DVD video format, AVI files support multiple streaming audio and video, although these features are seldom used. A codec popularly used for AVI is MPEG-4 ASP, usually encoded by DivX or Xvid, although many other codecs can also be contained in an AVI file.

Interchange File Format (IFF) is a generic digital container file format originally introduced by Electronic Arts (in cooperation with Commodore) in 1985 to facilitate transfer of data between software produced by different companies.

IFF files do not have any standard filename extension. On many systems that generate IFF files, file extensions are not important because the operating system stores file format metadata separately from the file name. The .iff filename extension is commonly used for the ILBM image file format, which uses the IFF container format.

MP2 (formally MPEG-1 Audio Layer II or MPEG-2 Audio Layer II, sometimes incorrectly called Musicam) is a lossy audio compression format. It is standardised as one of the three audio codecs of MPEG-1 alongside MPEG-1 Audio Layer I (MP1) and MPEG-1 Audio Layer III (MP3). The MP2 abbreviation is also used as a common file extension for files containing this type of audio data, or its extended variant MPEG-2 Audio Layer II.

MPEG-1 Audio Layer II was developed by Philips, CCETT and IRT as the MUSICAM algorithm, as part of the European-funded Digital Audio Broadcasting (DAB) project. Alongside its use on DAB broadcasts, the codec has been adopted as the standard audio format for Video CD and Super Video CD media, and also for HDV. On the other hand, MP3 (which was developed by a rival collaboration led by Fraunhofer Society called ASPEC) gained more widespread acceptance for PC and Internet applications. MP2 has a lower data compression ratio than MP3, but is also less computationally intensive.

JPEG 2000 (JP2) is an image compression standard and coding system. It was developed from 1997 to 2000 by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi (later the JPEG president), with the intention of superseding their original JPEG standard (created in 1992), which is based on a discrete cosine transform (DCT), with a newly designed, wavelet-based method. The standardized filename extension is '.jp2' for ISO/IEC 15444-1 conforming files and .jpx or .jpf for the extended part-2 specifications, published as ISO/IEC 15444-2. The MIME types for JPEG 2000 are defined in RFC 3745. The MIME type for JPEG 2000 (ISO/IEC 15444-1) is image/jp2.

The JPEG 2000 project was motivated by Ricoh's submission in 1995 of the CREW (Compression with Reversible Embedded Wavelets) algorithm to the standardization effort of JPEG LS. Ultimately the LOCO-I algorithm was selected as the basis for JPEG LS, but many of the features of CREW ended up in the JPEG 2000 standard.

High Efficiency Image File Format (HEIF) is a digital container format for storing individual digital images and image sequences. The standard covers multimedia files that can also include other media streams, such as timed text, audio and video.

HEIF can store images encoded with multiple coding formats, for example both SDR and HDR images. HEVC is an image and video encoding format and the default image codec used with HEIF. HEIF files containing HEVC-encoded images are also known as HEIC files and often use the .heic filename extension. Such files require less storage space than the equivalent quality JPEG.

Waveform Audio File Format (WAVE, or WAV due to its filename extension; pronounced /wæv/ or /weɪv/ ) is an audio file format standard for storing an audio bitstream on personal computers. The format was developed and published for the first time in 1991 by IBM and Microsoft. It is the main format used on Microsoft Windows systems for uncompressed audio. The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.

WAV is an application of the Resource Interchange File Format (RIFF) bitstream format method for storing data in chunks, and thus is similar to the 8SVX and the Audio Interchange File Format (AIFF) format used on Amiga and Macintosh computers, respectively.

In information and communications technology, a media type, content type or MIME type is a two-part identifier for file formats and content formats. Their purpose is comparable to filename extensions and uniform type identifiers, in that they identify the intended data format. They are mainly used by technologies underpinning the Internet, and also used on Linux desktop systems.

The Internet Assigned Numbers Authority (IANA) is the official authority for the standardization and publication of these classifications. Media types were originally defined in Request for Comments RFC 2045 (MIME) Part One: Format of Internet Message Bodies (Nov 1996) in November 1996 as a part of the MIME (Multipurpose Internet Mail Extensions) specification, for denoting type of email message content and attachments; hence the original name, MIME type. Media types are also used by other internet protocols such as HTTP, document file formats such as HTML, and the XDG specifications implemented by Linux desktop environments, for similar purposes.