Ana səhifə

International organisation for standardisation organisation internationale de normalisation

Yüklə 1.39 Mb.
ölçüsü1.39 Mb.
1   2   3   4   5   6   7   8   9   ...   23

0.9 System reference decoder

Part 1 of ISO/IEC 13818 employs a "System Target Decoder," (STD), one for Transport Streams (refer to 2.4.2 on page 11) referred to as "Transport System Target Decoder"(T-STD) and one for Program Streams (refer to 2.5.2 on page 54) referred to as "Program System Target Decoder"(P STD), to provide a formalism for timing and buffering relationships. Because the STD is parameterized in terms of ITU T Rec. H.222.0†|†ISO/IEC 13818 fields (for example, buffer sizes) each elementary stream leads to its own parameterization of the STD. Encoders shall produce bit streams that meet the appropriate STD's constraints. Physical decoders may assume that a stream plays properly on its STD; the physical decoder must compensate for ways in which its design differs from that of the STD.

0.10 Applications

The streams defined in this document are intended to be as useful as possible to a wide variety of applications. Application developers should select the most appropriate stream.

Modern data communications networks may be capable of supporting ITU T Rec. H.222.0†|†ISO/IEC 13818 video and ISO/IEC 13818 audio. A real time transport protocol is required. The Program Stream may be suitable for transmission on such networks.
The Program Stream is also suitable for multimedia applications on CD-ROM. Software processing of the Program Stream may be appropriate.
The Transport Stream may be more suitable for error-prone environments, such as those used for

distributing compressed bit-streams over long distance networks and in broadcast systems.

Many applications require storage and retrieval of ITU-T Rec. H.222.0†|†ISO/IEC 13818 bitstreams on various digital storage media (DSM). A Digital Storage Media Command and Control (DSM CC) protocol is specified in Annex A and part 6 of this Recommendation†|†International Standard in order to facilitate the control of such media.
Information technology -- Coding of moving pictures and associated audio

Section 1: General

1.1 Scope

ITU T Rec. H.222.0†|†ISO/IEC 13818-1 specifies the system layer of the coding. It was developed principally to support the combination of the video and audio coding methods defined in parts 2 and 3 of this Recommendation†|†International Standard. The system layer supports five basic functions: 1) the synchronization of multiple compressed streams on decoding, 2) the interleaving of multiple compressed streams into a single stream, 3) the initialization of buffering for decoding start up, 4) continuous buffer management, and 5) time identification.

An ITU T Rec. H.222.0†|†ISO/IEC 13818-1 multiplexed bit stream is either a Transport Stream or a Program Stream. Both streams are constructed from PES packets and packets containing other necessary information. Both stream types support multiplexing of video and audio compressed streams from one program with a common time base. The Transport Stream additionally supports the multiplexing of video and audio compressed streams from multiple programs with independent time bases. For almost error-free environments the Program Stream is generally more appropriate, supporting software processing of program information. The Transport Stream is more suitable for use in environments where errors are likely.
An ITU T Rec. H.222.0†|†ISO/IEC 13818-1 multiplexed bit stream, whether a Transport Stream or a Program Stream, is constructed in two layers: the outermost layer is the system layer, and the innermost is the compression layer. The system layer provides the functions necessary for using one or more compressed data streams in a system. The video and audio parts of this Specification define the compression coding layer for audio and video data. Coding of other types of data is not defined by the specification, but is supported by the system layer provided that the other types of data adhere to the constraints defined in 2.7. on page 81.

1.2 Normative References

The following Recommendations and International standards contain provisions which, through reference in this text, constitute provisions of this Recommendation†|†International Standard. At the time of publication, the editions indicated were valid. All Recommendations and International Standards are subject to revision, and parties to agreements based on this Recommendation†|†International Standard are encouraged to investigate the possibility of applying the most recent editions of the Recommendations and International Standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. The Telecommunications Standardization Bureau of the ITU maintains a list of currently valid ITU T Recommendations.

1.3 Identical Recommendations†|†International Standards

ITU T Rec. H.262†|†ISO/IEC 13818-2:1994 Information technology - Coding of moving pictures and associated audio - Part 2: Video.

1.4 Additional references

ISO 8859-1:1987, Information processing- 8 bit single-byte coded graphic character Sets - Part 1: Latin alphabet No. 1.

ISO/IEC 11172-1:1993 Information technology - Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s - Part 1: Systems.
ISO/IEC 11172-2:1993 Information technology - Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s - Part 2: Video.
ISO/IEC 11172-3:1993 Information technology - Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s - Part 3 Audio.
ISO/IEC 13818-3:1994 Information technology - Generic coding of moving pictures and associated audio information- Part 3 Audio.
Recommendation ITU-R BT.601.3 Encoding parameters of digital television for studios.
Recommendation ITU-R BT.470-2 Television systems.
Recommendation ITU-R BR.648 Digital recording of audio signals.
Report ITU-R BO.955.2 Satellite sound broadcasting of vehicular, portable, and fixed receivers in the range 500 - 3000MHz.
CCITT Recommendation J.17 Pre-emphasis used on Sound-Programme Circuits.
IEEE Standard 1180-1990 Standard Specification for the Implementations of 8 by 8 Inverse Discrete Cosine Transform.
IEC Publication 908:1987, CD Digital Audio System.
ISO/CD 13522-1;1993 Information technology - Coded representation of multimedia and hypermedia information objects - Part 1:Base notation..
ISO/CD 639-2; 1991, Terminology - Codes for presentation of names of languages - Part 2: Alpha-3 code.

1   2   3   4   5   6   7   8   9   ...   23

Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur © 2016
rəhbərliyinə müraciət