Disclaimer: This project is an independent, open-source implementation with no affiliation with, endorsement from, or connection to the DVB Project or the DVB Organisation. The acronym "dvb" in this project refers exclusively to the dvb (Digital Video Broadcasting) technology standard as defined in relevant technical specifications. This tool implements the dvb subtitle specification for interoperability purposes only. Use of the term "dvb" is for technical reference and does not imply any official status or authorization from the DVB Organisation.

srt2dvbsub is an attempt at a professional command-line tool that converts SRT (SubRip) subtitle files into dvb (Digital Video Broadcasting) subtitle tracks and multiplexes them directly into MPEG-TS (Transport Stream) files.

Essential for broadcasters, IPTV providers, and content distribution networks that need to deliver broadcast-compliant dvb subtitles embedded in transport streams. Replaces the need for expensive proprietary dvb authoring tools.

Key Features:

• SRT to dvb subtitle conversion
• Multi-track subtitle support (up to 8 simultaneous tracks)
• Professional text-to-bitmap rendering (Pango/Cairo)
• Direct MPEG-TS multiplexing
• Automatic resolution detection (SD, HD, UHD)
• Multi-threaded rendering for high performance
• ASS/SSA tag support and rendering (optional)
• Advanced 9-position canvas positioning with per-track margins
• ASS alignment tag recognition ({\an<digit>}) for per-subtitle positioning
• Custom MPEG-TS PID assignment with validation
• Manual bitrate control with enhanced bitrate detection
• Independent PNG output for preview and quality control
• SRT Quality control (QC) verification mode
• Full rendering control (fonts, colors, sizing)
• Per-track language codes and flags (forced, hearing-impaired)

• ** NEW ** PID preservation: mirror input MPEG-TS PIDs for A/V streams and allocate
  subtitle PIDs for new subtitle tracks
• ** NEW ** Subtitle Track Overwrite to replace existing dvbsub tracks for
  selected languages via --overwrite LANGS (SPTS-only)
• ** NEW ** Directory-based batch encoding: recursively process directory trees with
  template-based subtitle resolution and in-process encoding for automated workflows

For detailed build instructions, see BUILD.md.

# Convert and multiplex a single English SRT file srt2dvbsub \ --input video.ts \ --output video_with_subs.ts \ --srt subtitles.srt \ --languages eng

# Add English and German subtitles with delays srt2dvbsub \ --input video.ts \ --output video_with_subs.ts \ --srt eng.srt,deu.srt \ --languages eng,deu \ --delay 100,200

# Position subtitles at top-left with custom margins srt2dvbsub \ --input video.ts \ --output video_styled.ts \ --srt subtitles.srt \ --languages eng \ --sub-position top-left \ --margin-left 3.5 \ --margin-top 5.0

# Custom font, colors, anti-aliasing, and positioning srt2dvbsub \ --input video.ts \ --output video_styled.ts \ --srt subtitles.srt \ --languages eng \ --font "Open Sans" \ --fontsize 40 \ --fgcolor "#ffffff" \ --outlinecolor "#000000" \ --sub-position middle-center \ --ssaa 4

# Generate PNG files for preview without full MPEG-TS encoding srt2dvbsub \ --png-only \ --png-dir ./subtitle_previews \ --srt subtitles.srt \ --languages eng \ --font "Liberation Sans" \ --fontsize 40

# Validate subtitle file without encoding srt2dvbsub --qc-only --srt subtitles.srt --languages eng

The built-in batch engine allows you to process entire directory trees of media files in a single command. It recursively scans for .ts files, mirrors the directory structure to the output location, and automatically resolves subtitles based on configurable templates.

Key Features:

• Recursive Scanning: Finds all .ts files in the input tree.
• Directory Mirroring: Recreates the input folder structure in the output directory.
• Smart Subtitle Resolution: Looks for subtitles in a parallel subtitle directory OR alongside the video file.
• In-Process Execution: Fast and efficient; no external shell scripts required.
• Dry Run Mode: Preview exactly what will happen before processing any files.

Basic Example:

srt2dvbsub \ --batch-encode \ --batch-input /media/movies \ --batch-output /media/movies_processed \ --batch-srt /media/subtitles

Advanced Example with Custom Templates: This example clears default templates and defines specific patterns for English and German subtitles, while applying custom font styling to all files.

srt2dvbsub \ --batch-encode \ --batch-input /media/master/HD-TV \ --batch-output /media/output/HD-TV \ --batch-srt /media/subs/HD-TV \ --batch-clear-templates \ --batch-template "${SHOW}_S${SEASON}_E${EPISODE}.en.srt|eng" \ --batch-template "${SHOW}_S${SEASON}_E${EPISODE}.de.srt|deu" \ --ssaa 6 --font "Open Sans" --font-style "Light" --font-size 50 \ --margin-bottom 7.5 --delay 100 --overwrite eng,deu --no-unsharp

Template Variables:

• ${BASENAME}: Filename without extension
• ${SHOW}: Detected show name
• ${SEASON}: Detected season (e.g., S01)
• ${EPISODE}: Detected episode (e.g., E01)

See WORKFLOW.md and DETAILS.txt for comprehensive documentation on batch mode configuration.

• SRT (SubRip) parsing with robustness enhancements
• ASS/SSA tag and rendering support (with --ass flag)
• Multi-track processing with independent settings
• Per-track language codes (dvb 3-letter ISO codes)
• Per-track forced and hearing-impaired flags

• Professional rendering via Pango/Cairo (or libass)
• Configurable fonts, styles, and sizes
• Dynamic font sizing based on video resolution
• Custom vertical positioning (adjustable from bottom of screen)
• Custom colors: foreground, outline, shadow, background
• Supersample anti-aliasing (SSAA) with configurable factors

• MPEG-TS multiplexing with original streams preserved
• dvb Page Composition Segment generation
• Palette modes: EBU broadcast, broadcast, greyscale
• Automatic dithering and color reduction
• Unsharp mask filter (optional)

• Multi-threaded rendering (configurable worker threads)
• Per-track delay adjustment
• Benchmark mode for performance analysis
• Memory pooling and optimization

See full documentation with:

srt2dvbsub --help

-I, --input FILE Input media file (MPEG-TS, MP4, MKV, etc.) -o, --output FILE Output MPEG-TS file -s, --srt FILES Comma-separated SRT files -l, --languages CODES Comma-separated dvb language codes (e.g., eng,deu,fra) 

--font FONTNAME Font family (default: DejaVu Sans) --fontsize N Fixed size in pixels (8-72) --fgcolor #RRGGBB Text color (default: white #ffffff) --outlinecolor #RRGGBB Outline color (default: gray) --shadowcolor #AARRGGBB Shadow color with optional alpha --bg-color #RRGGBB Background color (optional - default: transparent) --sub-position POSITION Position on canvas: top-left, top-center, top-right, middle-left, middle-center, middle-right, bottom-left, bottom-center (default), bottom-right --margin-top PERCENT Top margin as % of canvas (0.0-50.0%, default: 3.5%) --margin-left PERCENT Left margin as % of canvas (0.0-50.0%, default: 3.5%) --margin-bottom PERCENT Bottom margin as % of canvas (0.0-50.0%, default: 3.5%) --margin-right PERCENT Right margin as % of canvas (0.0-50.0%, default: 3.5%) 

--pid PID[,PID2,...] Custom subtitle track PIDs (32-8186) --ts-bitrate BITRATE Override output bitrate in bps (100k-1G, default: auto-detect) --palette MODE Color palette: ebu-broadcast, broadcast, greyscale --ssaa N Anti-aliasing factor (1-24, default: 4) --no-unsharp Disable sharpening filter --png-only Generate PNG files only (skip MPEG-TS encoding) --png-dir PATH Output directory for PNG files 

--delay MS[,MS2,...] Delay in ms (per-track or global) --forced FLAGS Forced flags per track (0 or 1) --hi FLAGS Hearing-impaired flags per track (0 or 1) 

--render-threads N Parallel rendering workers (0=serial) --enc-threads N FFmpeg encoder threads (0=auto) --qc-only Quality check without encoding --debug N Verbosity: 0=quiet, 1=normal, 2=verbose, 3=ultra --bench Enable performance timing output --png-dir PATH Debug PNG output directory 

--ass Enable libass rendering (if built with --enable-ass) --list-fonts List available system fonts --license Show license information 

1. IPTV/OTT Platforms: Deliver broadcast-compliant dvb subtitles with custom positioning
2. Archive Digitization: Convert text based subtitle formats to dvb subtitles
3. Broadcast Mastering: Multi-language subtitle preparation with precise positioning
4. Content Distribution: Quality-controlled subtitle delivery with per-track customization
5. Automated Encoding: Pipeline integration for batch processing
6. Closed Caption Import: Automatically respect ASS positioning tags from MPEG-2 CC extraction
7. Preview Generation: Generate PNG previews for QA before full encoding
8. Stream Management: Custom PID assignment and bitrate control for compliant multiplexing

Typical performance on 8-core system:

• C11 compiler (GCC 5.0+, Clang 3.8+)
• FFmpeg development libraries (58.0+)
• Pango 1.52.1+
• Cairo 1.18.0+
• Fontconfig 2.15.0+
• libass 0.17.1+ (optional)
• pkg-config, autotools

• FFmpeg libraries
• Pango/Cairo libraries
• Fontconfig
• TrueType/OpenType fonts Open Sans DejaVu Sans Roboto Liberation Sans

See BUILD.md for detailed build instructions including:

• Prerequisites for different Linux distributions
• macOS Homebrew setup
• FreeBSD installation
• Build configuration options

• README.md (this file) - Program overview
• BUILD.md - Build and installation instructions
• DETAILS.txt - Comprehensive technical reference

Run srt2dvbsub --help for command-line reference with language codes.

Here are examples of the output of the srt2dvbsub program:

SD Subtitle (Font: Open Sans, Style: Light, Size: 24):

HD Subtitle (Font: Open Sans, Style: Medium, Size: 42):

UHD Subtitle (Font: Open Sans, Style: Light, Size: 84):

srt2dvbsub \ --input input.ts \ --output output.ts \ --srt english.srt,german.srt,french.srt \ --languages eng,deu,fra \ --font "Liberation Sans" \ --fontsize 36 \ --fgcolor "#ffffff" \ --outlinecolor "#000000"

srt2dvbsub \ --input batch_video.ts \ --output batch_output.ts \ --srt subs.srt \ --languages eng \ --render-threads 8 \ --enc-threads 8 \ --ssaa 2 \ --no-unsharp 

srt2dvbsub \ --input input.ts \ --output output.ts \ --srt sdh.srt,forced.srt \ --languages eng,eng \ --hi 1,0 \ --forced 0,1

srt2dvbsub --qc-only --srt subtitles.srt --languages eng # Outputs detailed validation report to qc_log.txt

Personal Use License: Free for personal, educational, and non-commercial use.

Commercial Use: Requires paid Commercial License from copyright holder.

• Contact: license@capsaworks-project.de
• Website: www.capsaworks-project.de

See --license flag for full terms and warranty disclaimer.

• Bugs & Features: bugs@capsaworks-project.de
• Licensing: license@capsaworks-project.de
• Repository: GitHub - srt2dvbsub

Copyright © 2025 Mark E. Rosche, Capsaworks Project
All rights reserved.