A .NET 9 C# library for parsing and extracting data from MXF (Material Exchange Format), extracted data streams, VBI (Vertical Blanking Interval), T42 (Teletext packet stream), and MPEG-TS (Transport Stream) files, with SMPTE timecode and Teletext caption support (OP-42 & OP-47 in particular).
A .NET 9 C# library for parsing and extracting data from MXF (Material Exchange Format) files and extracted data streams, VBI (Vertical Blanking Interval), and T42 (Teletext packet stream) files, with SMPTE timecode and Teletext caption support.
Features
Multi-format support: MXF, extracted data streams, VBI, and T42 file parsing
Format conversion: Automatic VBI ↔ T42 conversion, plus RCWT and EBU STL output
Teletext filtering: Magazine and row-based filtering with Unicode mapping
SMPTE timecode: Full timecode calculations with various frame rates
MXF processing: Stream extraction and demuxing capabilities
CLI tool: Unified opx command-line interface
Subtitle formats: RCWT (Raw Captions With Time) and EBU STL (EBU-Tech 3264) export
Format conversions: Convert between HD and SD T42 and VBI formats or vice versa. You can even pipe that data to other applications like ffmpeg or mpv.
ANSI Escaped Teletext: Supports parsing and filtering of teletext data with ANSI escape sequences:
Quick Start
Installation
Add the package reference to your project file from NuGet.org.
# Filter teletext data by magazine and rows
opx filter -m 8 -r 20,22 input.vbi
# Convert between formats (use -of / --output-format)
opx convert -of t42 input.vbi
# Convert to EBU STL subtitle format
opx convert -of stl -c input.mxf output.stl
# Extract streams from MXF files
opx extract -k d,v input.mxf
Using the Library
using nathanbutlerDEV.libopx.Formats;
// Parse and filter teletext data
using var vbi = new VBI("input.vbi");
foreach (var line in vbi.Parse(magazine: 8, rows: new[] { 20, 22 }))
{
Console.WriteLine(line);
}
libopx/
├── apps/opx/ # CLI tool
├── lib/ # Main library
│ ├── Formats/ # Format parsers (MXF, MXF data stream, VBI, T42)
│ ├── SMPTE/ # SMPTE metadata system
│ └── Enums/ # Enumeration definitions
├── samples/ # (Deprecated in repo) Obtain sample media from Release
│ assets (e.g. v1.0.0) and place here if needed
├── scripts/ # Development scripts
└── tests/ # xUnit test suite
Development
# Clone and build
git clone https://github.com/nathanpbutler/libopx
cd libopx
dotnet build
# Run tests
dotnet test
vhs-teletext - Software to recover teletext data from VHS recordings (inspiration for filter command)
MXFInspect - Tool for displaying the internal structure of MXF files (was super helpful for understanding MXF parsing and the intricacies of SMPTE timecodes)
bmxtranswrap - BBC's MXF processing library and utilities (inspiration for extract command)
SubtitleEdit - An incredibly useful C# library and software for subtitle editing and processing
CCExtractor - Closed caption and subtitle extraction and processing
ffmpeg - The swiss army knife of multimedia processing
