MPEG-2

MPEG-2 is a generic MPEG standard for video compression encoding video and audio encoding audio compression, lossy both. Generic means in this context that a data format and a decoding procedure is established without specifying parameters such as resolution, which determine the quality.

Introduction

MPEG -2 was introduced in 1994 and is a supplement to and successor of MPEG-1.

The MPEG - 2 codec uses a total of 818 patents that apply to a large part of the world. Of these, so far 400 patents expired (as of April 1, 2012). On April 1, 2014, the last of the relevant patents will expire.

Large dissemination won by the DVD standard: These are encoded in MPEG -2 ( video). The audio portion of the DVD can be also known as MPEG -2 Audio Layer -2 ( ISO / IEC 13818-3 ) encoded, but this is hardly used in practice; almost always, the audio signal is sometimes additionally stored on DVDs in Dolby Digital (AC -3 ) and DTS. Also on SVCD is MPEG -2 used, but with - compared to DVD - lower resolution and lower data rate.

The different variants (DVB -S, DVB- C, DVB -T) digital television use still preferred the MPEG -2 format.

Survey

MPEG-2 consists of several components that are defined in ISO / IEC 13818:

(Part 8: 10-bit extension of the video was intended for television studios and was due to lack of interest from the industry withdrawn)

MPEG- 2 Video

The essential features of MPEG -1 remained in MPEG- 2 are: separation of the color information from black -and-white image and coarsening the same as the human eye perceives color differences coarser than brightness differences; Dividing the image into 8x8 pixel sized blocks whose data requirements are reduced greatly by Discrete Cosine Transform and subsequent quantization; Summary of four blocks of 16x16 pixel macroblocks whose similarity is also used data reducing to macroblocks in the previous and / or images; and use of binary codes with variable length bit strings to represent more frequent shorter as can rarer.

Resolution up to 15 Mbit / s or at a higher chrominance ( color ) and to 50 Mbit / s - - On the video side, the MPEG -2 standard is aimed at higher quality and associated data rates than its predecessor MPEG -1 and support as opposed MPEG-1 and the interlacing. MPEG -2 was originally scheduled for digital television broadcasts and studio applications. MPEG -1 was not completely replaced, for low data rates, it is still a better choice than MPEG-2.

MPEG-2 Audio

On the audio side is an extension of all three layers at lower data rates and more channels ( 5.1 or 7.1) included. There are two variants of multi- channel coding: the backward-compatible, you can use the bit stream generated useful in the MPEG -1 decoder, and a non -backwards-compatible version ( english non backward compatible, NBC ). The NBC version is in Part 7 of the MPEG- 2 standards under the name AAC ( Advanced Audio Coding).

MPEG -2 file formats

To interlacing of video and audio MPEG -2 defines the video streaming formats program stream (PS) and Transport Stream (TS). Over time MPEG -2, but used in a variety of file formats. Below is an overview, where MPEG -2 files are typically encountered:

  • . mpg (can be MPEG -1 or MPEG-4)
  • . m2v (MPEG -2 Video Elementary Stream)
  • . m2a (MPEG -2 Audio Elementary Stream)
  • . m2s (MPEG -2 Elementary Data Stream)
  • . ts (MPEG -2 Transport Stream)
  • . vob (DVD Video Object)
  • . vro (Video Recording Object)
  • . mod ( MPEG -2 with AC3 audio, for example, JVC or Panasonic video cameras )
  • . m2t (MPEG -2 transport, for example to HD cameras Sony )
International Electrotechnical Commission MPEG-1 Audio Layer I MPEG-1 Audio Layer II Frame rate Bitrate MPEG-7 MPEG LA
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