Container format (digital)
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A container format is a computer file format that can contain various types of data, compressed by means of standardized codecs. The container file is used to identify and interleave the different data types. Simpler container formats can contain different types of audio codecs, while more advanced container formats can support audio, video, subtitles, chapters, and meta-data (tags) - along with the synchronization information needed to play back the various streams together.
Some containers are exclusive to audio:
- WAV (RIFF file format, widely used on Windows platform)
- AIFF (IFF file format, widely used on Mac OS platform)
Other flexible containers can hold many types of audio and video, as well as other media. The most popular multi-media containers are:
- IFF (first platform independent container format)
- AVI (the standard Microsoft Windows container, also based on RIFF)
- MOV (standard QuickTime container)
- MPEG-2 transport stream (TS) (standard container for digital broadcasting; typically contains multiple video and audio streams, and an electronic program guide) and program stream (PS)
- MP4 (standard container for the MPEG-4 multimedia portfolio)
- Ogg (standard container for Xiph.org codecs)
- ASF (standard container for Microsoft WMA and WMV)
- RealMedia (standard container for RealVideo and RealAudio)
- Matroska (not standard for any codec or system, but it is an open standard).
- 3gp (used by many mobile phones)
There are many other container formats, such as NUT, MPEG, MXF, ratDVD, SVI, DivX Media Format, and VOB.
Other containers are exclusive to still images:
- the TIFF (Tagged Image File Format) is a wrapper file format for still images and associated metadata.
- the Flexible Image Transport System is a wrapper file format for still images, raw data, and associated metadata.
See the Comparison of container formats for details regarding these formats.
[edit] Issues
The differences between various container formats arise from five main issues:
- Popularity; how widely supported a container is.
- Overhead. This is the difference in file-size between two files with the same content in a different container. For a two-hour film, when in AVI, the file may be up to 3MB larger than when in Matroska.
- Support for advanced codec functionality. Older formats such as AVI do not support new codec features like B-frames, VBR audio, VFR natively, although the format may be "hacked" to add support, creating compatibility problems.
- Support for advanced content, such as chapters, subtitles, meta-tags, user-data.
- Support of streaming media
[edit] See also
[edit] Related links
| Multimedia compression formats | |
|---|---|
| Video compression formats | ISO/IEC: MPEG-1 | MPEG-2 | MPEG-4 | MPEG-4/AVC | ITU-T: H.261 | H.262 | H.263 | H.264 | SMPTE: VC-1 Others: AVS | Dirac | Indeo | MJPEG | RealVideo | Theora | VP7 | WMV |
| Audio compression formats | ISO/IEC MPEG: MPEG-1 Layer III (known as MP3) | MPEG-1 Layer II | AAC | HE-AAC ITU-T: G.711 | G.722 | G.722.1 | G.722.2 | G.723 | G.723.1 | G.726 | G.728 | G.729 | G.729a Others: AC3 | ATRAC | FLAC | iLBC | Monkey's Audio | Musepack | RealAudio | SHN | Speex | Vorbis | WavPack | WMA |
| Image compression formats | ISO/IEC/ITU-T: JPEG | JPEG 2000 | JPEG-LS | JBIG | JBIG2 Others: BMP | GIF | ILBM | PCX | PNG | TGA | TIFF | WMP |
| Media container formats | 3GP | ASF | AVI | FLV | Matroska | MP4 | MXF | NUT | Ogg | Ogg Media | QuickTime | RealMedia Audio only: AIFF | AU | WAV |
