VBI Explorer User Windows Documentation – The Teletext Archaeologist

VBI Recorder captures Vertical Blanking Interval (VBI) data from composite video signals. VBI data carries information — such as teletext — that was historically broadcast alongside analogue television signals. The captured data can be saved to file for archival and later processing.

Requirements

VBI Recorder works exclusively with the August VGB100 USB Video Capture Card. Without this specific device and its drivers installed, the software will not be able to capture any data. The VGB100 can be purchased from the August International website.

Windows (7 or later recommended)
August VGB100 USB Video Capture Card with drivers installed
Composite video source (e.g. a VHS player or TV receiver with a VBI signal)

Getting Started

Connect your August VGB100 to a USB port and ensure its drivers are installed.
Connect your composite video source to the VGB100’s input.
Launch VBI Recorder. The status indicator will show Ready when the capture device has been found and the signal graph is running.

Recording VBI Data

Select Record mode using the radio button at the top of the window.
Click Browse… and choose a destination file. Files are saved with the .vbi extension.
Click Start Recording. The button will turn red and the elapsed time counter will begin.
When you have captured everything you need, click Stop Recording. The file is finalised and the recorder returns to a ready state.

Note: Make sure your video source is playing and producing a signal before you start recording.

Playing Back a Recording

VBI Recorder includes a built-in playback mode so you can review previously captured files.

Select Playback mode using the radio button.
Click Browse… and open a .vbi file.
Click Start Playback. The file will play at the original capture rate (PAL 50 fields/second) and the VBI visualiser will display the signal data frame by frame.
Click Stop Playback at any time to end early.

The VBI Signal Visualiser

The lower portion of the window shows a real-time greyscale visualisation of the raw VBI signal. Each horizontal band represents one VBI line; the brightness of each pixel corresponds to the sample value at that position. This is useful for confirming that a signal is present and that the data looks well-formed.

You can hide the visualiser by unchecking Show live VBI. The window will resize automatically.

Options

Option	Description
Debug output	Enables verbose logging in the log panel. Useful for diagnosing hardware or signal issues. Only available in Record mode.
Show live VBI	Toggles the VBI signal visualiser on or off. Hiding it makes the window more compact.

Themes

VBI Recorder supports light, dark, and system-default themes. Go to View > Theme and choose from:

System Default — follows your Windows appearance setting and updates automatically if you change it while the app is open.
Light
Dark

The Log Panel

The black panel in the middle of the window shows status messages from the capture engine. If an error occurs — for example, if the VGB100 cannot be found — the details will appear here. Enabling Debug output will produce additional messages showing internal graph events, which can help with troubleshooting.

Deconvolving

Once captured, you need to process the .vbi file that you saved to turn it into a T42 file that can be viewed in another tool, such as Teletext Player or Teletext Recovery Editor.

Install Alastiarvhs-teletext from https://github.com/ali1234/vhs-teletext

The command to do this is:

teletext deconvolve '[path-to-input-file.vbi]' > '[path-to-output-file.t42]' -k -c saa7131

The “-c saa7131” is important as it tells the deconvolver what chip is in your USB dongle. “-k” means to keep blank VBI lines (as these keep the timing correct when playing back in Teletext Player).

Troubleshooting

Status shows an error on startup
The most likely cause is that the August VGB100 is not connected or its drivers are not installed. Connect the device and restart the application.

Recording produces an empty or very small file
Check that your composite video source is switched on and outputting a signal. The VBI data is only present in lines above the visible picture area; if the source is not producing a standard analogue signal, no data will be captured.

Playback looks blank or corrupted
The file may have been recorded from a source with no active VBI signal, or may be incomplete. Try a different recording.

This software is provided “as is”, without warranty of any kind.