By assigning attributes to each individual subtitle or text row, a translator is in full control to improve the overall quality of the programme by making subtitles cover a foreign language text, or the opposite to move a subtitle so it doesn’t cover areas of the picture normally used by the subtitles. To make this work these attributes must be stored in the subtitle file. Most text formats only store text and timecode and nothing more, but of course it’s possible to implement attributes for this. But this is the reason there already exists subtitle file formats that support various attributes for this purpose. The EBU subtitle file format supports vertical position, justification and colors, for example. The Cavena 890 format adds exact line vertical position, background type (like black box or not), transparency level, dual font support and Asian language support.
Fonts are generally not controlled by the translator, but is set by the broadcaster as it is often a channel branding factor. However, in the Cavena Tempo and 890 format it is possible to switch between a main and secondary font, typically an open subtitle and closed subtitle font in a mixed file containing both open and closed subtitles. Mixed files are not supported in the EBU file format, mixed files are used in countries that normally use subtitles for translated text and the programme have local language spoken, which is then subtitled via closed transmission formats like teletext.
Override or do all setting at the broadcasters site will not give us the possibility for required temporary changes.
The solution is a combination, where the translators prep tool works with default values on all attributes, so default vertical position, default background etc. The actual vertical position, background etc is then set by the broadcaster in the transmission equipment. Now if the translator lifts the subtitle vertical position, or sets a black box background etc, those specific attributes are fixed for that specific subtitle and overrides the transmission settings.
So for proper handling and display of subtitles, giving higher quality experience for the viewers, text and time code is not enough. Therefore use of better subtitle file formats than simple text documents is needed.