📺 Teletext VBI Decoder

Extract hidden teletext data from VBI scanlines in captured images

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Drop VBI image here or click to upload

Supports PNG, BMP, TIFF, JPEG — ideally raw captures with VBI scanlines visible

ℹ How it works

Teletext data was broadcast in the Vertical Blanking Interval (VBI) — the invisible scanlines at the top of each TV frame.

This decoder extracts that hidden data by:

  1. Finding clock run-in — the alternating 10101... sync pattern
  2. Detecting framing code — byte 0xE4 marks data start
  3. Decoding Hamming 8/4 — error-corrected magazine/row bytes
  4. Extracting text — 40 characters per packet with parity checking

Upload a raw VBI capture image, or click "Generate Demo" to try it out with synthetic data!