Fix/tx3g timestamp bug by DhanushVarma-2 · Pull Request #2199 · CCExtractor/ccextractor

DhanushVarma-2 · 2026-03-13T06:54:52Z

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Fixes #2198. Corrects tx3g subtitle timestamps on the FFmpeg demuxer path.

Override fts_now with DTS-based timestamp to fix wrong start times caused by gap packets
Pass AVPacket.duration to fix last subtitle using video end instead of actual subtitle end
Add rounding to DTS-to-ms conversion to prevent truncation errors

Replace GPAC with FFmpeg for MP4 demuxing via a Rust implementation using rsmpeg. Supports AVC/H.264, HEVC/H.265, CEA-608, CEA-708, and tx3g subtitle tracks. Includes chapter extraction via ccxr_dumpchapters. VobSub tracks are detected but not yet supported. Selected at compile time via ENABLE_FFMPEG_MP4 / enable_mp4_ffmpeg Cargo feature.

- mp4_rust_bridge.c/.h: C-callable functions for AVC/HEVC/CC processing - ccx_gpac_types.h: compat defines for GF_4CC, GF_ISOM_SUBTYPE_C708, etc. - mp4.c: dispatch to Rust demuxer when ENABLE_FFMPEG_MP4 is set - ccextractor.c: iterate all input files in MP4 mode - Remove dead processmp4_ffmpeg/dumpchapters_ffmpeg declarations

- src/CMakeLists.txt: link swresample, re-add libs after ccx_rust for circular dependencies, --no-as-needed on Linux, ENABLE_HARDSUBX - lib_ccx/CMakeLists.txt: target_compile_definitions for ENABLE_HARDSUBX - rust/CMakeLists.txt: enable_mp4_ffmpeg Cargo feature

set_fts() produces stale fts_now values after empty tx3g gap packets, causing subtitle start times to be incorrect. Override fts_now with the correct DTS-based millisecond timestamp before calling process_tx3g. Fixes CCExtractor#2198

Pass AVPacket.duration through ccx_mp4_process_cc_packet so the last subtitle ends at start+duration instead of video end.

ccextractor-bot · 2026-03-16T11:59:25Z

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 578abca...:

Report Name	Tests Passed
Broken	10/13
CEA-708	2/14
DVB	3/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	77/86
Teletext	20/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2...
ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65...
ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b...
ccextractor --out=spupng c83f765c66...
ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...

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

ccextractor --out=srt --latin1 --autoprogram 73d9313d64..., Last passed:
Test 8738
ccextractor --out=ttxt --latin1 001dd8cdf7..., Last passed:
Test 8738
ccextractor --out=srt --latin1 4d4e938ef6..., Last passed:
Test 8738
ccextractor --service 1 --out=txt --no-bom --no-rollup ea83ff7bcb..., Last passed:
Test 8738
ccextractor --service 1 --out=txt f17524b53f..., Last passed:
Test 8738
ccextractor --service 1 --out=txt 80848c45f8..., Last passed:
Test 8738
ccextractor --service 1 --out=txt --no-bom --no-rollup b5d6aad89f..., Last passed:
Test 8738
ccextractor --service 1[EUC-KR] --out=txt --no-rollup b5d6aad89f..., Last passed:
Test 8738
ccextractor --service 1 --out=srt da904de35d..., Last passed:
Test 8738
ccextractor --service 1 --out=sami da904de35d..., Last passed:
Test 8738
ccextractor --service 1[EUC-KR] b5d6aad89f..., Last passed:
Test 8738
ccextractor --service 1[EUC-KR] --no-rollup b5d6aad89f..., Last passed:
Test 8738
ccextractor --service all da904de35d..., Last passed:
Test 8738
ccextractor --service all[EUC-KR] b5d6aad89f..., Last passed:
Test 8738
ccextractor --service 1,2[UTF-8],3[EUC-KR],54 --out=txt da904de35d..., Last passed:
Test 8738
ccextractor --autoprogram --out=srt --latin1 d41b53b504..., Last passed:
Test 8738
ccextractor --stdout --quiet --no-fontcolor 79a51f3500..., Last passed:
Test 8738
ccextractor --stdout --quiet --no-fontcolor 767b546f96..., Last passed:
Test 8738
ccextractor --service 1 c83f765c66..., Last passed:
Test 8738
ccextractor --myth c83f765c66..., Last passed:
Test 8738
ccextractor --in=raw fb79021542..., Last passed:
Test 8738
ccextractor --mp4vidtrack 5df914ce77..., Last passed:
Test 8738
ccextractor --xmltv=3 --out=null 96efd279cf..., Last passed:
Test 8738
ccextractor --datapid 2310 --autoprogram --out=srt --latin1 e639e54550..., Last passed:
Test 8738

Congratulations: Merging this PR would fix the following tests:

ccextractor --startcreditsnotafter 2 --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 · 2026-03-16T12:22:34Z

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results, when compared to test for commit 578abca...:

Report Name	Tests Passed
Broken	10/13
CEA-708	2/14
DVB	3/7
DVD	3/3
DVR-MS	2/2
General	25/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	75/86
Teletext	20/21
WTV	13/13
XDS	34/34

Your PR breaks these cases:

ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2...
ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65...
ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b...
ccextractor --out=spupng c83f765c66...
ccextractor --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsnotbefore 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsnotafter 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...
ccextractor --startcreditsforatmost 2 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9...

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

ccextractor --out=srt --latin1 --autoprogram 73d9313d64..., Last passed:
Test 8611
ccextractor --out=ttxt --latin1 001dd8cdf7..., Last passed:
Test 8611
ccextractor --out=srt --latin1 4d4e938ef6..., Last passed:
Test 8611
ccextractor --service 1 --out=txt --no-bom --no-rollup ea83ff7bcb..., Last passed:
Test 8611
ccextractor --service 1 --out=txt f17524b53f..., Last passed:
Test 8611
ccextractor --service 1 --out=txt 80848c45f8..., Last passed:
Test 8611
ccextractor --service 1 --out=txt --no-bom --no-rollup b5d6aad89f..., Last passed:
Test 8611
ccextractor --service 1[EUC-KR] --out=txt --no-rollup b5d6aad89f..., Last passed:
Test 8611
ccextractor --service 1 --out=srt da904de35d..., Last passed:
Test 8611
ccextractor --service 1 --out=sami da904de35d..., Last passed:
Test 8611
ccextractor --service 1[EUC-KR] b5d6aad89f..., Last passed:
Test 8611
ccextractor --service 1[EUC-KR] --no-rollup b5d6aad89f..., Last passed:
Test 8611
ccextractor --service all da904de35d..., Last passed:
Test 8611
ccextractor --service all[EUC-KR] b5d6aad89f..., Last passed:
Test 8611
ccextractor --service 1,2[UTF-8],3[EUC-KR],54 --out=txt da904de35d..., Last passed:
Test 8611
ccextractor --autoprogram --out=srt --latin1 d41b53b504..., Last passed:
Test 8611
ccextractor --stdout --quiet --no-fontcolor 79a51f3500..., Last passed:
Test 8611
ccextractor --stdout --quiet --no-fontcolor 767b546f96..., Last passed:
Test 8611
ccextractor --service 1 c83f765c66..., Last passed:
Test 8611
ccextractor --myth c83f765c66..., Last passed:
Test 8611
ccextractor --in=raw fb79021542..., Last passed:
Test 8611
ccextractor --mp4vidtrack 5df914ce77..., Last passed:
Test 8611
ccextractor --xmltv=3 --out=null 96efd279cf..., Last passed:
Test 8611
ccextractor --datapid 2310 --autoprogram --out=srt --latin1 e639e54550..., Last passed:
Test 8611

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.

DhanushVarma-2 · 2026-03-16T12:45:06Z

output Is correct

DhanushVarma-2 · 2026-03-16T12:48:28Z

Note: CCExtractor's SRT encoder subtracts 1ms from end times to prevent
subtitle overlap (ccx_encoders_common.c:1240). This is by design.
Internal timestamps are exact.

DhanushVarma-2 · 2026-03-16T13:49:46Z

@cfsmp3 #2199 fixes tx3g timestamps on the FFmpeg path (depends on #2170) — wrong start times from gap packets and last subtitle ending at video end instead of actual duration. Both fixed, tested against ffmpeg reference. Note: the GPAC path on master has the same bug but worse (overflow to 0xFFFFFFFF) — can fix separately if needed.

Dhanush Varma added 6 commits March 10, 2026 16:16

fix: use packet duration for tx3g last subtitle end time

f30a360

Pass AVPacket.duration through ccx_mp4_process_cc_packet so the last subtitle ends at start+duration instead of video end.

merge: sync with upstream master

39d9a49

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Fix/tx3g timestamp bug#2199

Fix/tx3g timestamp bug#2199
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DhanushVarma-2:fix/tx3g-timestamp-bug

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