Embed Subtitles
Burn SRT subtitles into video files using FFmpeg.
Prerequisites
No SRT file? Use the transcribe skill first to generate subtitles from audio/video.
Need translation? After transcribing, read the SRT, translate each entry preserving timestamps, write new SRT file. No API needed.
Quick Start
cd ~/.claude/skills/embed-subtitles/scripts
# Burn SRT into video
npx ts-node embed-subtitles.ts -i video.mp4 -s subtitles.srt -o output.mp4
# Custom styling
npx ts-node embed-subtitles.ts -i video.mp4 -s subtitles.srt -o output.mp4 \
--font-size 24 --position bottom --margin 40
# Add credit text overlay at end
npx ts-node embed-subtitles.ts -i video.mp4 -s subtitles.srt -o output.mp4 \
--credit "Your Name" --credit-position topOptions
| Option | Short | Default | Description |
|---|---|---|---|
--input | -i | (required) | Input video file |
--subtitles | -s | (required) | SRT subtitle file |
--output | -o | (required) | Output video file |
--font-size | 20 | Font size in pixels | |
--font-name | Arial | Font family name | |
--position | bottom | Subtitle position: top, center, bottom | |
--margin | 25 | Margin from edge in pixels | |
--color | white | Text color | |
--outline | 2 | Outline thickness | |
--shadow | 1 | Shadow depth | |
--credit | Credit text to show at end | ||
--credit-position | top | Credit position: top, bottom | |
--credit-duration | 2.5 | Credit display duration in seconds | |
--extract-frame | Extract frame at specified second for verification |
Position Values
top- Near top of video (good for credits, avoids bottom burned-in text)center- Middle of videobottom- Near bottom of video (traditional subtitle position)
Dependencies
- FFmpeg (must be installed and in PATH)
RTL Auto-Detection & Fix (CRITICAL)
Before embedding ANY SRT file, Claude MUST check if the content is RTL.
Detection
Read the SRT file and check if the majority of text lines contain Hebrew/Arabic/Farsi characters:
- Hebrew range:
\u0590-\u05FF - Arabic range:
\u0600-\u06FF - Farsi additional:
\u0750-\u077F
If RTL content is detected, apply the fix BEFORE passing to FFmpeg.
RTL Fix
Wrap each text line (not index numbers, not timestamps) with Unicode directional marks:
python3 -c "
import re
with open('SRT_FILE_PATH', 'r', encoding='utf-8') as f:
content = f.read()
lines = content.split('\n')
result = []
for line in lines:
stripped = line.strip()
if stripped and not re.match(r'^\d+$', stripped) and not re.match(r'\d{2}:\d{2}:\d{2}', stripped):
line = '\u202B' + line + '\u202C'
result.append(line)
with open('SRT_FILE_PATH', 'w', encoding='utf-8') as f:
f.write('\n'.join(result))
"- U+202B (RLE - Right-to-Left Embedding): forces RTL paragraph direction
- U+202C (PDF - Pop Directional Formatting): closes the embedding
This fixes: English words at line start, periods/commas on wrong side, mixed bidi text.
When to apply
Claude should analyze the SRT content intelligently:
- If most text is Hebrew/Arabic/Farsi → apply RTL fix
- If mixed but predominantly RTL → apply RTL fix
- If LTR (English, Spanish, etc.) → skip
- No flag needed from the user - detect automatically
Notes
- For Arabic credits, use English text due to FFmpeg drawtext RTL limitations
- Use
--extract-frameto verify subtitle positioning before final render