[FIX]: Properly decode DVB EIT start time BCD field in XMLTV output

[x15sr71]

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---

Description

This PR fixes improper BCD decoding in DVB EIT start time fields, which was causing invalid XMLTV timestamps.

Problem

As reported by @TPeterson94070 in #1835 (comment), CCExtractor was generating invalid start times in XMLTV output for DVB streams:

Example of broken output:

<programme start="202601311184512+0000" stop="20260131122400 +0000" channel="40001">

Root Cause

The EPG_DVB_calc_start_time() function printed the raw 24-bit BCD time field as a numeric value without decoding individual BCD nibbles into HH/MM/SS, which resulted in invalid timestamps.

Solution

Properly decode BCD nibbles for hours, minutes, and seconds, then use struct tm + mktime() for normalization - aligning with the existing EPG_DVB_calc_end_time() implementation.

Testing

Test stream: channel41.ts

Before Fix:

<programme start="202601311184512+0000" stop="20260131122400 +0000" channel="40001">
<programme start="202601311188864+0000" stop="20260131123500 +0000" channel="40001">

• Invalid: BCD time values printed as raw decimal instead of being decoded ( channel41_epg.xml )

After Fix:

<programme start="20260131121300 +0000" stop="20260131122400 +0000" channel="40001">
<programme start="20260131122400 +0000" stop="20260131123500 +0000" channel="40001">

• All 986 events have valid timestamps ( channel41_epg_fixed.xml )

Validation:

# All timestamps parse correctly
grep 'programme start' channel41_epg.xml \
| sed -E 's/.*start="[0-9]{8}([0-9]{6}).*/\1/' \
| while read t; do
  h=${t:0:2}; m=${t:2:2}; s=${t:4:2}
  if [ "$h" -gt 23 ] || [ "$m" -gt 59 ] || [ "$s" -gt 59 ]; then
    echo "BAD: $t"
  fi
done
# Result: 0 invalid timestamps

And Successfully imported into @TPeterson94070's PVR application -#1835 (comment)

Impact

• Fixes DVB EIT XMLTV output to generate valid timestamps
• Aligns start time and stop time decoding logic
• No changes to ATSC codepath
• Enables DVB EPG support for downstream applications

[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 5c05173...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	6/7
DVD	3/3
DVR-MS	2/2
General	27/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	85/86
Teletext	21/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2...
• ccextractor --out=spupng c83f765c66...

Congratulations: Merging this PR would fix the following tests:

• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed: Never
• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed: Never
• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never

It seems that not all tests were passed completely. This is an indication that the output of some files is not as expected (but might be according to you).

Check the result page for more info.

[ccextractor-bot]

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results, when compared to test for commit 5c05173...:

Report Name	Tests Passed
Broken	13/13
CEA-708	14/14
DVB	6/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	81/86
Teletext	21/21
WTV	13/13
XDS	34/34

NOTE: The following tests have been failing on the master branch as well as the PR:

• ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed:

  Test 8271

• ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed:

  Test 8271

• ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed:

  Test 8271

• ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 8271

• ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 8271

• ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 8271

• ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 8271

• ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed:

  Test 8271

This PR does not introduce any new test failures. However, some tests are failing on both master and this PR (see above).

Check the result page for more info.