信息技术 - 多媒体应用格式（MPEG-A） - 第19部分:通用媒体应用格式（CMAF）

[中文适用范围]： 本文件规定了CMAF多媒體格式，包含適合串流傳輸和在終端用戶設備上自适应マルチmédia presentations中解碼的片段化メディアオブジェクト。CMAF規定了從ISO基础媒體文件格式衍生而來的トラック形式，并从中派生出可用于存儲和交付的可.getAddressable media objects. CMAF規定了共享編碼和包裝約束條件的トラック集合，這些條件允許選擇多個トラック以形成マルチmédia presentation並實現相同內容的不同比特率、帧率、分辨率等的無縫切換。CMAF規定了hypothetical application model，該模型確定如何在CMAFpresentation中組合和同步各_tracks以形成マルチmédia presentation。此模型抽象了交付方式，允許使用任何交付方法。hypothetical application model假設有manifest和player，但CMAF未指定manifest、player或交付协议，意圖使其支持此modelo aplicativo的任何內容都可以使用。CMAF規定了媒體畫質和brands，這些畫質限制了CMAF_tracks的媒體編碼和包裝以實現無縫自适应切換並使設備能夠通過其brand识别兼容内容。CMAF規定了presentation profiles，這些profiles conditionalmente要求符合指定媒體プロファイル的CMAF_tracks，並允許內容創建者和設備識別兼容的マルチmédia presentations. CMAF通过規定如何指定和标识新的メディアプロファイル和presentationプロファイル以及提供這些建議來實現擴展性。 [外文原描述]： This document specifies the CMAF multimedia format, which contains segmented media objects optimized for streaming delivery and decoding on end user devices in adaptive multimedia presentations. CMAF specifies a track format derived from the ISO base media file format, then derives addressable media objects from CMAF tracks that can be used for storage and delivery. CMAF specifies sets of tracks that share encoding and packaging constraints that enable the selection of multiple tracks to form a multimedia presentation and allow seamless switching of alternative encodings of the same content at different bit rates, frame rates, resolution, etc. CMAF specifies a hypothetical application model that determines how tracks in a CMAF presentation are intended to be combined and synchronized to form a multimedia presentation. The model abstracts delivery to allow any delivery method. The hypothetical application model assumes a manifest and player, but CMAF does not specify a manifest, player, or delivery protocol, with the intent that any that support the hypothetical application model can be used. CMAF specifies media profiles and brands that constrain media encoding and packaging of CMAF tracks to enable seamless adaptive switching of tracks and allow devices to identify compatible content by its brand. CMAF specifies presentation profiles that conditionally require sets of CMAF tracks conforming to specified media profiles and allow content creators and devices to identify compatible multimedia presentations. CMAF enables extensibility by specifying how new media profiles and presentation profiles can be specified and identified and includes guidelines for those specifications.