streamNumber

Use this setting to select a single captions track from a source. Stream numbers include all tracks in the source file, regardless of type, and correspond to either the order of tracks in the file, or if applicable, the stream number metadata of the track. Although all tracks count toward these stream numbers, in this caption selector context, only the stream number of a track containing caption data may be used. To include more than one captions track in your job outputs, create multiple input captions selectors. Specify one stream per selector. If your source file contains a track which is not recognized by the service, then the corresponding stream number will still be reserved for future use. If more types of caption data get recognized in the future, these numberings will not shift.