Subtitle sample description
An atom that defines how to interpret subtitle media data.
Overview
The subtitle sample description contains information that defines how to interpret subtitle media data. This sample description is based on the standard sample description header, as described in Sample description atom ('stsd').
The data format field in the sample description is currently always set to 'tx3g'. Unrecognized data formats should be ignored. The text media described here is based on the text box defined in the 3GPP Timed Text specification but provides a different track type and media handler designed specifically for subtitles.
The subtitle media handler adds some of its own fields to the sample description.