2017년 1월 30일 월요일

Codec

Codec

A device or the software which are bi-directionally made by encoding (encoding) and the decode (decoding) of data using an encoding method in codec (Codec) [1] [2] [3] [4] [5]. In addition, is used as a term referring to algorithm of that purpose [6]; [7] [8] [9].

The device which converts the data such as software and a sound or the animation to compress data using a data compaction function, and to extend into a different form and software are included in codec.

It was a term of the field of telecommunications where the codec meant a device originally to transmit and receive data with a digital communication line. The etymology is an abbreviation of coder/decoder.

Table of contents

Various codec

By the development such as a digital gadget or the personal computer (PC), the codec often points at a digital code interval and the thing converting between digital data now. It was old, and, for example, a digital code referred to the DA converter which converted an analog signal, AD converter when I called it audio codec, audio codec.

The techniques that communicated such as a sound or the image were put to practical use using the technique that compressed a digital image in the 1980s, and communicated in analog network through a modem and a digital line in earnest, and these integrated circuits (IC) which it processed appeared. I came to call the IC that audio codec, the compression of the image extended an IC to use for a mark, the decoding of the sound image codec. G.711 codec, the latter to use, for example, for sound communication of the ISDN to the former include codec to use for G3, image compression, the extension of the G4 facsimile.

When the 1990s began, compression, the codec that I could extend of the picture came up with the neighboring hardware of the PC. I became able to perform compression, the extension such as an image or the sound by the rapid progress of the computer softly and appeared in the software codec that I handled only by software afterwards. The codec often points at data compaction, the device extending of the digital code and software now.

But data compaction, the codec extending is equivalent to one category in the group of the codec and points to the codec in the small meaning. The word codec is not used very much, but the following things are usually codec in the wider meaning, too.

  • I handle the MIME encoding decode used by an E-mail
  • I perform decoding (URL decode) of the character string of the URL in encoding (URL encoding), reverse for character string such as %xx
  • I perform the interconversion (e.g., BMP ⇔ TIFF ⇔ PICT) between the image data format without the compression
  • I perform the decoding of the coding of data and encrypted data

Instead of putting the processing that I cannot restore for original data at a stage of the compression, there is a thing using the high irreversible compression (called Lossy) compressing that I use reversible compression (called Lossless) that original data can be completely restored to the original state for codec of the data compaction. The former is used by the document file that it is necessary to be restored to the original state for perfection and some images, audio files. The latter is used for an image, the sound that data size is easy to come to have a big generally, the high efficiency compression of the animation by the reversible compression. I refer to → data compaction.

Data compaction, the codec that I extend

For example, in a canonical form type of Microsoft Windows, as for the sound, as for PCM, the image, the file data of the state of no compression (non-compression) including BMP exist. What I treat by no compression may be suitable to treat a short sound and animation used frequently by a system, a small image, but when I am going to treat a picture and a sound of the big size as no compression, large-capacity memory or hard disk are necessary, and traffic quantity increases. I compress a file in order to avoid it, and it becomes necessary to hold down size. It is codec for data compaction, the extension on this occasion that is necessary.

Codec of the image compression

  • Reversible compression to GIF -256 colors
  • JPEG XR (HD Photo) - Irreversible compression, choice of the reversible compression are allowed by designation
  • JPEG - irreversible compression
  • Reversible compression to PNG - up to 48bit (each color 16bit) full color (approximately 280 trillion colors), an alpha channel (transparentize) of 8bit (256 phases) are possible
  • WebP - irreversible compression, choice of the reversible compression are possible. Google developed it.
  • The reversible compression of the two level image: I am used by facsimiles.
    • MH (modified huffman) - Consecutive head compression
    • MR (modified READ: relative element address designate) - Two-dimensional encoding
    • MMR (Modified Modified READ) - ITU-T T.6
    • JBIG (Joint Bi-lebel Image experts Group) - Arithmetic Coding

Codec of the speech compression

There is the codec that the music intended for without limiting human utterance to codec and it for main sound bands which I intend and encode in codec of the speech compression. Because the former uses a characteristic of the utterance of the person, the encoding of the sound is possible at the encoding rate that is lower than the latter.

Various codec (follows) of the ITU-G series advice is used with a cell-phone or IP telephone widely and, with the representative thing of the codec for sound bands, compress a sound in 4 - 13kbps degree. With the representative thing of the codec that the music intended for, there are ATRAC used for mini-disc (MD) which came up in the early 1990s and the MP3 that has begun to penetrate with a PC audio system widely from the about the end of 1990s. For example, I am compressed in comparison with a compact disk (CD) with the compression audio system of the stereo sound of 128kbps by less than 1/10. These completely use the irreversible compression method that cannot be restored to the original state for an original sound.

On the other hand, in late years the data size increases in the codec using the reversible compression not to cause deterioration at all although I grow big because the capacity of the recording medium increased drastically. This can perform compression of the 70% degree from about 60%.

Codec of the animation compression

Irreversible compression of the high efficiency becomes required to treat large-capacity data by the animation. There is MPEG-2 used for DVD with the representative thing.

  • Codec of the irreversible compression
    • AVS (Advanced Audio Video Coding Standard in Information Technology) - China's original codec
    • Codec for the animation editing that Canopus HQ Codec - Canopus developed
    • Cinepak
    • Daala
    • The codec that research and development section of Dirac - British Broadcasting Corporation (BBC) developed
    • The codec that is adopted in DV CODEC - digital video camera
    • The codec that was made an international standard by ITU-T
      • H.261 - Codec for the ISDNTV meeting system
      • H.262 - Codec and equivalence of the MPEG-2
      • H.263 - Codec of the compression that is higher than H.261 which assumed the modem for the telephone
        • H.The codec that was derived than 263
          • The codec that DivX - DivX, Inc. develops. I am based on MPEG-4 ASP.
          • The H.263 (MPEG-4) codec of the Xvid - open source. I am based on MPEG-4 ASP.
          • I am based on 3ivx - MPEG-4 ASP.
      • H.The codec that improved 263+ - H.263
      • H.264 - The codec that improved H.263 for higher compressibility. It is the same as MPEG-4 AVC.
        • The video codec that AVC-Intra - Panasonic developed. H.I am based on 264.
        • H.264 encoding library of the x264-free.
      • H.265
    • The codec that Indeo Video - Intel Corp. developed
    • MEI - animation ERI
    • Microsoft Video 1
    • The codec that is adopted with Motion JPEG - digital camera
    • Motion JPEG 2000
    • The codec that was standardized by MPEG
      • Codec to be used in MPEG-1 - video CD
      • The codec that is adopted by MPEG-2 - DVD, terrestrial digital broadcast
      • Codec to be used in MPEG-4 - carrying contents
        • The codec that was derived than MPEG-4
          • MS-MPEG4 (Microsoft MPEG-4 Video Codec) - It is unrelated to MPEG, but there are MPEG-4 and compatibility
            • Pirated edition of AngelPotion - MS-MPEG4
            • Pirated edition of DivX 3.11 - MS-MPEG4
            • Windows Media Video MS-MPEG4 was made by a standard
          • RMP4 (REALmagic MPEG-4 Video Codec) - The codec that U.S. Sigma Designs company developed. It was found out to have misappropriated a source code of Xvid.
      • MPEG-4 AVC
    • Codec (TrueMotion) which On2 developed
      • The codec that it is become VP3 - open source and can use free
      • The codec that is used for VP4 - China's original optical disk standard EVD
      • I am based on the VP5 - above.
      • The codec that is adopted in VP6 - Adobe Flash.
      • Codec of the high pressure shrinkage higher-resolution than VP7 - VP6
    • Codec (including the thing by having purchased On2) that Google developed
      • I adopt it in WebM of VP8 - Google
      • VP9 - same as above
    • Codec of the RealVideo - RealNetworks company development. I am strong in a low rate
    • The codec that is supported by Snow - ffdshow
    • Codec for Sorenson Video - Quick Time movies
    • The codec that Theora - Xiph.org develops On2VP3 to a base
    • WMV9 (VC-1) - I adopt it on Blu-ray Disc, HD DVD
    • XVD
  • Codec of the reversible compression
    • AMV Video Codec - reversible irreversible compression codec
    • The codec that is used in AVIzlib - 3DCG animation production uses
    • The codec that is used for the high-resolution records of the Huffyuv - TV program. Multi-thread non-correspondence.

Footnote, reference

Allied item

It is acquired by "https://ja.wikipedia.org/w/index.php?title= codec &oldid=58380541"

This article is taken from the Japanese Wikipedia Codec

This article is distributed by cc-by-sa or GFDL license in accordance with the provisions of Wikipedia.

Wikipedia and Tranpedia does not guarantee the accuracy of this document. See our disclaimer for more information.

In addition, Tranpedia is simply not responsible for any show is only by translating the writings of foreign licenses that are compatible with CC-BY-SA license information.

0 개의 댓글:

댓글 쓰기

피드 구독하기: 댓글 (Atom)