Following up on the “cover art text description” thread, it has been suggested that all images in a Blorb file could have textual descriptions. And sounds, too, because why not.
Proposal for an addition to the Blorb spec:
For a game to be fully accessible to visually impaired users, it should provide textual descriptions to be displayed as alternatives to images. Similarly, audio resources should have textual descriptions as alternatives for hearing-impaired users.
The resource description chunk allows the Blorb file to offer this information.
4 bytes 'RDes' chunk ID 4 bytes len chunk length 4 bytes num number of entries ... entries
The entries are variable-length, and look like:
4 bytes usage resource usage 4 bytes number number of resource 4 bytes length length of text (bytes) length bytes text textual description (UTF-8, not null-terminated)
There should be at most one entry for each resource – that is, each (usage, number) pair.
Resource descriptions are not required, but they are recommended for significant sounds and images. (Images used for decoration, such as window borders or text dividers, may not need textual descriptions.) Data and executable chunks do not need descriptions; if they appear in this chunk, the interpreter can ignore them.
(An interpreter with a web interface would apply the textual description of an image as an “alt” attribute on the tag.)