2.9 Optimize media to reduce resource use
https://www.w3.org/TR/web-sustainability-guidelines/#optimize-media-to-reduce-resource-use
Include media only when it supports user needs. Manage, optimize, and load media efficiently. Ensure users have control over playback and data use.
Success Criterion: Need for media
Only include media when it supports user experience or improves understanding and keep the number of media items to a minimum.
Success Criterion: Optimized media
Resize, optimize, and compress media for different screen sizes, devices, and user needs. Use widely supported, efficient formats that enable native presentation or playback where possible. Avoid unnecessary custom or non-native media players. Use hardware-accelerated playback when available and compatible with security requirements.
Success Criterion: Lazy loading
Incorporate lazy and/or deferred loading from the start by identifying which media elements are required immediately and which should load only on user interaction. Load large or data-intensive media only when needed, using a non-functional static facade or placeholder to defer loading until user request or interaction.
Success Criterion: User-controlled media
Disable autoplay for audio, video, and other media by default. Ensure users can control playback and resolution. Inform users about media length, format, and expected data use. Provide the option to disable data-intensive media or offer lower-bandwidth alternatives.
Success Criterion: Media management and use
Create a media management and usage policy. Include guidance on compression, rendering performance, file formats, data retention, storage, review, and deletion.
