Kodning av information för ljud, bild, multimedia och hypermedia

Kommittébeteckning: SIS/TK 302 (Multimedia, kodning och representation)
Källa: ISO
Svarsdatum: den 4 jun 2019
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This part of ISO/IEC 14496 specifies the ISO base media file format, which is a general format forming the basis for a number of other more specific file formats. This format contains the timing, structure, and media information for timed sequences of media data, such as audio-visual presentations.

This part of ISO/IEC 14496 is applicable to MPEG-4, but its technical content is identical to that of ISO/IEC 15444-12, which is applicable to JPEG 2000.

Kommittébeteckning: SIS/TK 302 (Multimedia, kodning och representation)
Källa: ISO
Svarsdatum: den 9 jun 2019
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ISO/IEC 14496-12 specifies a format for the storage of timed resources such as media streams as well as of resources for which no timed stream structure exists, or when the timed stream structuredoes not need to be exposed.

This standard specifies how this format can be used to store web resources (e.g. HTML, JavaScript,CSS, …) and defines brands to identify files conforming to this standard. It also specifieshypothetical processing for how these files can be consumed by web browsers.

The specified storage enables the delivery of synchronized media and web resources as supported byISO/IEC 14496-12: file download, progressive file download, streaming, broadcast, etc.

This standard also defines how to signal required web capabilities to process the file. This is done in a way that web profiles defined by other organizations may be signaled in a dedicated box, e.g. the MIME Box, similarly to how it is done in 14496-30.

This standard does not define any profile for web data, only their carriage.

Kommittébeteckning: SIS/TK 302 (Multimedia, kodning och representation)
Källa: ISO
Svarsdatum: den 11 jun 2019
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This Recommendation | International Standard 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 ISO/IEC 13818. The system layer supports six 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;

5) time identification;

6) multiplexing and signalling of various components in a system stream.

A Rec. ITU-T 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.

A Rec. ITU-T 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 this Specification, but is supported by the system layer provided that the other types of data adhere to the constraints defined in 2.7.

Kommittébeteckning: SIS/TK 302 (Multimedia, kodning och representation)
Källa: ISO
Svarsdatum: den 19 jun 2019
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The scope of Common Media Application Format (CMAF) is the encoding and packaging of

segmented media objects for delivery and decoding on end user devices in adaptive

multimedia presentations. Segmented Media Objects are derived from encoded tracks for storage,

identification, and delivery. Delivery and presentation are abstracted by a hypothetical

application model for segmented Media Objects described by a manifest that allows a wide

range of implementations without specifying any.

CMAF constrains media encoding and packaging to allow interoperable adaptive delivery

of alternative tracks of segmented media to different devices, over different networks. ISO Base

Media File format file constraints and brand, CMAF defines CMAF Presentation Profiles, CMAF

Media Profiles and brands that specify track formats, media encoding constraints, and constraints on

sets of CMAF Tracks that can be adaptively selected or switched during playback. This

enables most Internet devices to play a CMAF Presentation conforming to a specified CMAF

Presentation Profile.

A manifest and player are assumed in the hypothetical application model. The manifest describes a

CMAF presentation and its media Resources, which reference addressable CMAF Media Objects. A

player can interpret a manifest, select, decode, synchronize, and present the Resources in

a continuous multimedia presentation consistent with the encoded CMAF Presentation.

CMAF does not specify a manifest, player, or delivery protocol, with the intent that any that

meet the functional requirements can be used.

See Section 6 for details of the CMAF Hypothetical Application Model, Media Object

Model, Specified Objects, and Profiles.

Kommittébeteckning: SIS/TK 302 (Multimedia, kodning och representation)
Källa: ISO
Svarsdatum: den 24 jun 2019
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This document specifies the framework, concepts, methodology for testing, and criteria to be achieved to claim conformance to multiple parts of ISO/IEC 21122 as listed below. It the procedures that shall be followed for conformance testing.

This document Specifies conformance testing procedures for decoders implementing ISO/IEC 21122-1

Specifies tests to check codestreams for conformance to ISO/IEC 21122-1. As such, it provides means to test whether encoder implementations generate syntactically correct codestreams, and whether codestreams generated by such implementations follow the requirements of a particular profile, level and sublevel, and the buffer model implied by them.

Specifies tests to check files for conformance to ISO/IEC 21122-3

Specifies conformance testing procedures that allow testing whether codestreams conform to any of the profiles specified in 21122-2.

Specifies conformance testing procedures that allow testing whether codestreams conform to the buffer model

specified in 21122-2 as part of a profile, level and sublevel.

Specifies codestreams, decoded images, and error metrics to be used within the decoder testing procedures

Provides a buffer model test Specifies abstract test suites

This document does not include the following tests:

Testing the reconstruction of a full resolution image from a subsampled image format. In particular, upsampling

from 4:2:2 to 4:4:4 sampling is a non-normative extension and as such its testing is beyond the scope of this document.

Testing the conversion of the sample values reconstructed by a ISO/IEC 21122-3 decoder to the target colour space by means of the colour specification box of ISO/IEC 21122-3

Testing of the composition of background and foreground for images reconstructed from ISO/IEC 21122-3 files or codestreams.

Acceptance testing: the process of determining whether an implementation satisfies acceptance criteria and

enables the user to determine whether or not to accept the implementation. This includes the planning and execution of several kinds of tests (e.g. functionality, quality, and speed performance testing) that demonstrate that the implementation satisfies the user requirement

Performance testing: measures the performance characteristics of an Implementation Under Test (IUT) such as its throughput, responsiveness, etc. under various conditions.

Robustness testing: the process of determining how well an implementation is able to conceal problems from attempting to reconstruct an image from an ill-formed codestream.