[PR #1869] feat(wtv): Add DVB teletext stream detection in WTV files #2648

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claunia · 2026-01-29T17:23:15Z

claunia commented

2026-01-29 17:23:15 +00:00

Original Pull Request: https://github.com/CCExtractor/ccextractor/pull/1869

State: closed
Merged: Yes

Summary

Adds detection of DVB teletext streams in WTV (Windows TV) files
Previously, teletext streams were silently ignored, producing empty output files

Changes

Add WTV_STREAM_TELETEXT GUID to recognize DVB teletext streams
Detect teletext by examining format subtype GUID at offset 0x4C in MSTVCAPTION metadata
Initialize teletext decoder when teletext stream is found
Add timing support for teletext streams
Wrap teletext data in PES headers for decoder compatibility

Known Limitation

WTV files store teletext in Microsoft's VBI sample format, which differs from standard DVB teletext data units. The decoder will process the data but may not extract subtitles from all WTV files. A warning message is displayed when teletext is detected.

Note: Even FFmpeg's libzvbi fails to decode the test sample with "Error decoding subtitles: Invalid data found when processing input", confirming this is a format compatibility issue rather than a CCExtractor bug.

Test Results

With the sample from #1391:

Before: Teletext stream not detected, 0 bytes output
After: Teletext stream detected, 1014 packets processed, warning displayed about format limitation

Fixes #1391

🤖 Generated with Claude Code

**Original Pull Request:** https://github.com/CCExtractor/ccextractor/pull/1869 **State:** closed **Merged:** Yes --- ## Summary - Adds detection of DVB teletext streams in WTV (Windows TV) files - Previously, teletext streams were silently ignored, producing empty output files ## Changes - Add `WTV_STREAM_TELETEXT` GUID to recognize DVB teletext streams - Detect teletext by examining format subtype GUID at offset 0x4C in MSTVCAPTION metadata - Initialize teletext decoder when teletext stream is found - Add timing support for teletext streams - Wrap teletext data in PES headers for decoder compatibility ## Known Limitation WTV files store teletext in Microsoft's VBI sample format, which differs from standard DVB teletext data units. The decoder will process the data but may not extract subtitles from all WTV files. A warning message is displayed when teletext is detected. Note: Even FFmpeg's libzvbi fails to decode the test sample with "Error decoding subtitles: Invalid data found when processing input", confirming this is a format compatibility issue rather than a CCExtractor bug. ## Test Results With the sample from #1391: - **Before:** Teletext stream not detected, 0 bytes output - **After:** Teletext stream detected, 1014 packets processed, warning displayed about format limitation Fixes #1391 🤖 Generated with [Claude Code](https://claude.com/claude-code)

claunia added the pull-request label 2026-01-29 17:23:15 +00:00

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Reference: starred/ccextractor#2648