BiDi and Plex Guide

Hebrew Subtitle BiDi & Plex/Infuse Formatting Guide

Language / שפה: English | עברית

The Core Problem: Punctuation Reversal in Modern Media Players

Modern media players (Plex, Infuse, VLC, Apple TV, Android TV, Smart TVs) use modern subtitle rendering engines (libass, ExoPlayer, AVPlayer) that default to Left-to-Right (LTR) embedding levels when rendering plaintext subtitles.

When a line containing Right-to-Left (RTL) text (such as Hebrew) ends with a neutral character (period, question mark, exclamation mark, hyphen, closing bracket, ellipses), the rendering engine treats the neutral punctuation as trailing LTR text, causing it to jump to the far right (the visual beginning of the line).

Example of the Reversal:

• Intended: ?מה שלומך
• Rendered incorrectly: מה שלומך? (with question mark on the right)
• Dialogue with hyphens: - כן, אני מבין. rendered as כן, אני מבין. -

The Solution: The SubRefine Invisible RLM Engine

Unicode character U+200F (RIGHT-TO-LEFT MARK - RLM) is a non-printable, zero-width formatting character with strong RTL directionality.

1. Leading RLM

Injecting \u200F as the very first character of every line forces the text shaper to start with an RTL base level, ensuring dialogue dashes (-) stay on the right.

2. Trailing RLM

Injecting \u200F immediately before trailing punctuation (?, !, ., ..., )) binds the punctuation strongly to the preceding Hebrew text, preventing it from flipping across the screen.

Automatic Rule Enforcement in RightSub

./rightsub merge and ./rightsub fix-plex automatically apply these rules along with homoglyph normalization, CP1255 encoding conversion, and SDH noise stripping via the SubRefine Engine.

3 Execution Modes for fix-plex:

1. Single File

./rightsub fix-plex "Movie.he.srt" --in-place

2. Multiple Specific Files

Pass multiple paths sequentially:

./rightsub fix-plex "S01E01.he.srt" "S01E02.he.srt" "S01E03.he.srt" --in-place

3. Whole Directory or Media Library (Recursive)

Recursively scan an entire season or library folder, cleaning ads and creating backups:

./rightsub fix-plex "/path/to/TV_Shows/" --recursive --in-place --clean-ads --backup

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Smart Safety & Filtering Architecture

The tool is engineered for worry-free batch operations on large, heterogeneous media libraries:

• Hebrew-Only Detection: Automatically inspects character distribution in each .srt file. English subtitles (.en.srt), Spanish, French, etc. are identified and skipped entirely ([SKIP] Not Hebrew). The script never touches non-Hebrew files.
• Subtitle-Only Filtering: Completely ignores video containers (MKV, MP4, AVI), poster art, or metadata files (.nfo).
• Strict Idempotency: Running repeatedly on already-fixed subtitles does not duplicate RLM marks or corrupt dialogue text.
• Safety Flags: Full support for --dry-run (preview mode with zero disk writes) and --backup (creates .srt.bak before editing in-place).