Overview
ISO/IEC 23001-15:2019 - "Information technology - MPEG systems technologies - Part 15: Carriage of web resources in ISOBMFF" defines how web resources (HTML, JavaScript, CSS, images, etc.) are stored and delivered inside the ISO Base Media File Format (ISOBMFF, ISO/IEC 14496-12). The standard specifies brands to identify conformant files, describes hypothetical processing models for consumption by web engines and media players, and explains signaling methods (for example using a dedicated MIME Box) to declare required web capabilities. It enables synchronized delivery of media and web content over file download, progressive download, streaming and broadcast.
Key topics and technical requirements
- Carriage model: Defines two storage classes - timed web resources (stored in tracks for time-driven presentation/synchronization) and non‑timed web resources (stored as file items).
- Tracks vs Items:
- Timed resources use tracks (sample-based) to support seeking, trick play and synchronization with audio/video.
- Non‑timed resources use ISOBMFF items that are cached by a web engine and treated as if downloaded from a URL constructed from the file base URL + item_name (item_name must be a relative URL).
- Hypothetical processing models:
- Media player integrating a web engine (player extracts samples/items, instantiates web engine).
- Web engine first (web page loads ISOBMFF which contains web content).
- Timed sample behavior: A sample becomes active at its presentation time and remains valid for the sample duration; implementations should consider processing delays and pre-fetching for synchronization.
- Track types: Examples include overlay HTML tracks (sample content conformant to W3C HTML), WebVTT metadata tracks, and text-content tracks for web applications. The brand 'htmt' is used to signal overlay HTML tracks; sample entries such as 'stxt' with MIME types like text/html are referenced.
- Signaling capabilities: Defines how to signal required web capabilities and external web profiles (without defining the profiles themselves), e.g. via a dedicated MIME Box similar to ISO/IEC 14496-30.
Practical applications and who uses this standard
- OTT / Streaming platforms: Deliver synchronized interactive overlays (captions, adverts, interactive UI) with video/audio streams.
- Media player and browser vendors: Implement playback engines that combine media decoding and web rendering.
- Content packagers and broadcasters: Package HTML/CSS/JS resources in ISOBMFF for progressive delivery, fragmented streaming, or broadcast.
- CDNs and streaming toolchains: Support caching and progressive item delivery for web-enhanced media.
- Application developers: Build interactive, timed web experiences tied to media (e.g., synchronized overlays, metadata-driven interfaces).
Related standards
Keywords: ISO/IEC 23001-15:2019, ISOBMFF, web resources in MP4, HTML overlays, timed web resources, MIME Box, MPEG systems, streaming, progressive download, synchronized media.
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