Problem
Japanese subtitles lose intended line breaks when full-width punctuation is normalized during export.
Solution
Root Cause / Diagnostic:
Export filters often strip or normalize full-width Japanese punctuation marks (such as Ideographic Space U+3000 or full-width periods U+3002) into half-width ASCII equivalents. This normalization alters character boundary metrics and causes automatic layout engines to collapse deliberate semantic line breaks.
Actionable Fix:
1. Set caption export encoding strictly to UTF-8 with BOM and disable automated ASCII character normalization routines.
2. Implement explicit XML-based line breaks (<br/> in TTML/SMPTE-TT or line breaks in SRT) rather than relying on full-width whitespace spacing.
3. Re-import the exported subtitle file into an external validator or preview player to confirm Japanese character line breaks and punctuation spacing match the master timeline.
Pro Tip:
Japanese broadcast standards (ARIB TR-B39) mandate keeping subtitle lines under 13 full-width characters per line; maintaining deliberate semantic breaks (kugiri) prevents viewer reading fatigue.
Export filters often strip or normalize full-width Japanese punctuation marks (such as Ideographic Space U+3000 or full-width periods U+3002) into half-width ASCII equivalents. This normalization alters character boundary metrics and causes automatic layout engines to collapse deliberate semantic line breaks.
Actionable Fix:
1. Set caption export encoding strictly to UTF-8 with BOM and disable automated ASCII character normalization routines.
2. Implement explicit XML-based line breaks (<br/> in TTML/SMPTE-TT or line breaks in SRT) rather than relying on full-width whitespace spacing.
3. Re-import the exported subtitle file into an external validator or preview player to confirm Japanese character line breaks and punctuation spacing match the master timeline.
Pro Tip:
Japanese broadcast standards (ARIB TR-B39) mandate keeping subtitle lines under 13 full-width characters per line; maintaining deliberate semantic breaks (kugiri) prevents viewer reading fatigue.