Subtitles are designed for hearing users, as they only cover spoken text and do not include sound effects or other audio elements. SDH, on the other hand, are designed for those who are deaf or hard of hearing, by including additional information, such as speaker tags, sound effects and other elements outside of speech. Closed captions are required by law on all public broadcasts, as per FCC regulations and are typically formatted as white text on a black background that can be positioned anywhere on the screen.
Yes. Users can always add additional comments when submitting a file, either by typing in notes or by attaching relevant files for added context. In fact, this is highly encouraged as the more context that is provided, the more accurate the technical output will be, resulting in even less human editing required and lower costs.