ISO/IEC 23000-19:2018 pdf download – Information technology — Multimedia application format (MPEG-A) — Part 19: Common media application format (CMAF) for segmented media.
6.5 CMAF specified objects and profiles
6.5.1 Object derivation and interoperability code points
ComrnonKedia App1iationEorrnat specities track formats and n TaT&rmatsT&enóding multimedia and metadata derived from the fragmented ISO Base Media File F&iñát and various iidio, video and subtitle media tormats.
H CMAF specifies encoded media objects in a CMAF track format that applies to all media types and determinesThäbjects that are encoded and decoded.
— CMAF speciFies logical setsiif encoded mediobjects iidtheir general ënëdding constraThts.
CMAF specifies profiles that determine the specific encoding constraints on media objects that conform to identified interoperability points called profiles.
— CMAF addressable media objects are derived by packaging CMAF headers, CMAF chunksnd CMAF fragments as ISOBMFF data structures availableTdi- stoe and delivery.
CMAF addressable media objectsTnherit the propertioTencodëd media objects, their profiles,ánd logical media object and set constraints, and make the process of encoding and decoding of CMAF fragments independent of the delivery method and packaging. Different delivery specifications can rnãj the same CMAF addressable media objects to their different manifests to enable interoperahility. CMAF addressable media objects, such as CMAF chunks and CMAF segments, are logically derived from CMAF fragments, but it is up to implementations whether to physically derive them from CMAF fragments by post processing or encode and package them direciW
6.5.2 Encoded media objecti
C?’.IAF specifies CMAF hcãds CN1AF fragmcLI I (\1\1 ti CMAF media profiles. These are tlw
6.5.3 Logical media object sets
— CMAF specifies CMAF switching sets that logically group CMAF tracks that are alternative encodings of the same content constrained to enable seamless switching. A CMAF switching set is constrained to simplify seamless switching between tracks by requiring time-aligned CMAF fragments, constrained encoding parameters, and shared encryption keys.
— CMAF specifies aligned CMAF switching sets that logically group multiple CMAF switching sets that are alternative encodings of the same content with time-aligned CMAF fragments. Some players can seamlessly switch between time-aligned CMAF fragments in different CMAF switching sets that are encoded with different characteristics, such as different codecs or encryption keys.
— CMAF specifies CMAF selection sets that logically group alternative CMAF switching sets based on their content and encoding constraints, e.g. alternative languages or codecs. At most, one CMAF track at a time is intended to be selected from each CMAF selection set in a CMAF presentation.
— CMAF specifies CMAF presentations that logically group CMAF tracks containing related synchronized content that can be selected, streamed, adaptively switched, decoded, decrypted, and synchronized on playback to render a multimedia presentation.
6.5.4 Addressable media objects
— CMAF specifies CMAF addressable media objects that are derived from CMAF tracks and fragments, and can be used for storage and delivery of a CMAF presentation. CMAF addressable media objects include CMAF headers, CMAF track files, CMAF segments, and CMAF chunks. CMAF fragment encoding and decoding are independent of the addressable media objects used to transport those CMAF fragments.
6.5.5? CMAF? profiles,? brand,? and? identifiers 6.5.5.1 Overview CMAF specifies the following brands and identifiers to support the creation and identification of interoperable content. They provide standardized conformance points for consistent content creation and validation. Players and devices can use these brands and identifiers to signal or recognize playback compatibility. — CMAF specifies CMAF media profiles and ISOBMFF brands for widely used audio, video, and subtitle formats. Each CMAF media profile specifies constraints on codecs, media samples, CMAF fragments, and CMAF tracks to identify encoder/decoder interoperability and optional functionality including random access and seamless adaptive switching specified as CMAF switching set constraints. CMAF also specifies guidelines for the specification of CMAF media profiles and matching brands to enable other specifications to define CMAF media profiles that conform to general CMAF requirements. See Table A.1, Table B.1, Table A.2, and Table A.3. — CMAF specifies CMAF presentation profiles and identifiers that conditionally require inclusion of CMAF tracks conforming to specific CMAF media profiles. CMAF presentations conforming to the CMAF presentation profiles in A.1 are intended to be compatible with most media playback devices.