[FIX]: Restore XMLTV generation for ATSC EIT/VCT streams and correct EIT bounds checks

[x15sr71]

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Description

Fixes #1759 - This PR restores functional XMLTV generation for ATSC broadcast streams, ATSC streams with VCT/TVCT tables now generate XMLTV output correctly.

Problem

The -xmltv parameter was being ignored for ATSC broadcast streams. When processing ATSC transport streams with valid EPG data (EIT tables) and channel information (VCT/TVCT tables), CCExtractor would:

• Generate SRT caption files (working correctly)
• NOT generate XMLTV files (the bug)

This made it impossible to extract Electronic Program Guide data from ATSC streams, despite the -xmltv parameter being specified.

Root causes identified:

1. EPG events stored in fallback storage (TS_PMT_MAP_SIZE) were never output
2. Inverted buffer boundary check logic prevented complete ATSC EIT parsing
3. Limited ATSC table ID support (missing extended EIT tables 0xCC-0xD0 and Cable VCT 0xC9)

Solution

Core Fixes

1. Fixed EPG output logic (EPG_output() function)

   • Modified to always check fallback storage, not only when nb_program == 0
   • ATSC streams store events in fallback due to VCT source ID mapping, but these were being ignored
   • Now correctly outputs events from both regular program storage and fallback storage

2. Fixed critical buffer boundary check (CHECK_OFFSET macro)

   • Corrected inverted logic from < to >
   • Before: if (offset + val < offset_end) (allowed buffer overruns)
   • After: if (offset + (val) > offset_end) (prevents overruns)
   • Applied to both EIT and VCT parsing functions

3. Extended ATSC table support (EPG_parse_table() function)

   • Added support for extended EIT table IDs: 0xCC, 0xCD, 0xCE, 0xCF, 0xD0
   • Added Cable VCT variant: 0xC9
   • Ensures comprehensive ATSC EPG data extraction

Testing

Tested with 1 2 sample files provided by @TPeterson94070:

• channel5FullTS.ts - 5 channels with VCT/TVCT tables
• ch12FullTS.ts - Additional ATSC test case
• ch29FullTS.ts - 5 programs with extended EIT data (Nov 26-28, 2025)

Before this fix:

./ccextractor channel5FullTS.ts --xmltv 1

• Output: Only .srt file generated
• No XMLTV file created (bug)

After this fix:

./ccextractor channel5FullTS.ts --xmltv 1

• Output: Both .srt AND .xml files generated
• XMLTV file contains:
  • Channel listings extracted from VCT
  • Program schedules parsed from EIT-0/1/2/3
  • UTC timestamps, titles, and subtitles properly captured
  • Unique ts-meta-id values matching EIT event IDs

Known Limitations

1. ATSC EIT timestamps appear incorrect in some streams (e.g., year showing as 2047). This is due to pre-existing limitations in ATSC date/time decoding logic.

2. XMLTV output uses numeric channel IDs instead of full ATSC channel names. VCT short_name and major/minor channel numbers are not currently mapped.

3. Some EIT events appear under channel="0". This happens when service_id does not map to a VCT-defined program.

Backward Compatibility

• No breaking changes to existing DVB/SDT functionality
• DVB streams continue to work as before
• SRT caption extraction unchanged for all stream types
• Only adds/fixes ATSC XMLTV generation

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Note on Known Limitations:

This PR focuses solely on fixing the core issue: restoring XMLTV generation for ATSC streams. The three accuracy issues mentioned above (incorrect dates, channel naming, orphaned programs) are data quality problems that existed in the codebase previously and are not directly caused by or related to the primary bug fix in this PR.

I believe these should be addressed in follow-up PRs for better separation of concerns. However, if maintainers prefer the date/time conversion issue (year 2047 bug) to be fixed in this PR due to its impact on usability, I'm happy to include it. Please advise on your preferred approach.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 42d7509...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	7/7
DVD	3/3
DVR-MS	2/2
General	27/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	86/86
Teletext	21/21
WTV	13/13
XDS	34/34

Congratulations: Merging this PR would fix the following tests:

• ccextractor --hardsubx 1a0302f7fd..., Last passed: Never

All tests passing on the master branch were passed completely.

Check the result page for more info.