DVD subtitles are already a separate layer to the movie stream, but it is a bitmap. Because it's a separate layer, OCR-ing should be easy.
And if you ask why it's a bitmap, that's because bitmaps support more than just plain text: color and typefaces to name 2 things. Imagine if DVD players have to implement text decoding ("Is this subtitle stream in UTF-8 or maybe some Cyrillic Code Page?") and rendering (color, placement, font files, etc...)
And if you ask why it's a bitmap, that's because bitmaps support more than just plain text: color and typefaces to name 2 things. Imagine if DVD players have to implement text decoding ("Is this subtitle stream in UTF-8 or maybe some Cyrillic Code Page?") and rendering (color, placement, font files, etc...)