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feat: replace GPAC with FFmpeg for MP4 demuxing #2170

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DhanushVarma-2:feat/replace-gpac-with-ffmpeg
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feat: replace GPAC with FFmpeg for MP4 demuxing #2170
DhanushVarma-2 wants to merge 3 commits intoCCExtractor:masterfrom
DhanushVarma-2:feat/replace-gpac-with-ffmpeg

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@DhanushVarma-2 DhanushVarma-2 commented Mar 4, 2026 •
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Adds a Rust FFmpeg-based MP4 demuxer (rsmpeg) as a compile-time alternative to GPAC. Enabled with cmake -DWITH_FFMPEG=ON.

Supported: AVC/H.264, HEVC/H.265, CEA-608, CEA-708, tx3g, chapter extraction
Known gap: VobSub detected but not decoded
GPAC path: Unchanged, still the default

Note: mp4_ffmpeg_exports.rs shows as binary in the diff due to null-terminated C string literals for FFI — the file is clean UTF-8.

@DhanushVarma-2 DhanushVarma-2 changed the title Feat/replace gpac with ffmpeg feat: replace GPAC with FFmpeg for MP4 demuxing Mar 5, 2026
@DhanushVarma-2 DhanushVarma-2 force-pushed the feat/replace-gpac-with-ffmpeg branch from 006130e to 4039844 Compare March 6, 2026 06:23
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DhanushVarma-2 commented Mar 6, 2026

The 9 Windows test failures (autoprogram, spupng, startcreditstext) are unrelated to MP4 demuxing — they involve subtitle encoding and credits detection, not the MP4 code path. These same tests pass on the Linux CI run. The Windows build itself was also delayed by a Chocolatey 503 outage when installing GPAC.

All 237 Linux tests pass, including the 3 MP4-specific tests. The Linux CI bot also notes this PR fixes 9 previously-broken tests that had never passed before.

@DhanushVarma-2 DhanushVarma-2 force-pushed the feat/replace-gpac-with-ffmpeg branch 13 times, most recently from 87f2178 to 9e95cd7 Compare March 7, 2026 06:59
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cfsmp3 commented Mar 7, 2026

Before going deep into this.

It would be a lot more readable to separate both implementations. Have process_mp4_ffmpeg and process_mp4_gpac functions, possibly in separate files, so we only need a few #ifdef guards.

Minimize the changes in the existing code (which already is not super well organized)...

Even (much better), do the ffmpeg part in rust. We don't want to add more C to the code - we really want to switch to rust.

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DhanushVarma-2 commented Mar 8, 2026

Before going deep into this.

It would be a lot more readable to separate both implementations. Have process_mp4_ffmpeg and process_mp4_gpac functions, possibly in separate files, so we only need a few #ifdef guards.

Minimize the changes in the existing code (which already is not super well organized)...

Even (much better), do the ffmpeg part in rust. We don't want to add more C to the code - we really want to switch to rust.

yeah sure.

feat: implement Rust FFmpeg MP4 demuxer using rsmpeg
2da4319 
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.
@DhanushVarma-2 DhanushVarma-2 force-pushed the feat/replace-gpac-with-ffmpeg branch from fd54002 to 513276d Compare March 10, 2026 10:48
Dhanush Varma added 2 commits March 10, 2026 16:32
feat: add C bridge for Rust FFmpeg demuxer and integrate into mp4.c
6a35080 
- 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
build: CMake and build.rs changes for FFmpeg MP4 demuxer
aa75430 
- 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
@DhanushVarma-2 DhanushVarma-2 force-pushed the feat/replace-gpac-with-ffmpeg branch from 513276d to aa75430 Compare March 10, 2026 11:03
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ccextractor-bot commented Mar 10, 2026

CCExtractor CI platform finished running the test files on linux. Below is a summary of the test results, when compared to test for commit 90128d8...:
Report Name Tests Passed
Broken 10/13
CEA-708 2/14
DVB 4/7
DVD 3/3
DVR-MS 2/2
General 27/27
Hardsubx 1/1
Hauppage 3/3
MP4 3/3
NoCC 10/10
Options 79/86
Teletext 20/21
WTV 13/13
XDS 34/34

Your PR breaks these cases:

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

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

    Test 8730

Congratulations: Merging this PR would fix the following tests:

  • ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed: Never
  • ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed: Never
  • ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed: Never
  • ccextractor --out=spupng c83f765c66..., Last passed: Never
  • ccextractor --parsePAT --out=srt c83f765c66..., 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 --startcreditsforatleast 1 --startcreditstext "CCextractor Start crdit Testing" c4dd893cb9..., Last passed: Never
  • ccextractor --endcreditsforatleast 3 --endcreditstext "CCextractor Ends crdit Testing" addf5e2fc9..., 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.

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ccextractor-bot commented Mar 10, 2026

CCExtractor CI platform finished running the test files on windows. Below is a summary of the test results, when compared to test for commit e4bcade...:
Report Name Tests Passed
Broken 10/13
CEA-708 2/14
DVB 4/7
DVD 3/3
DVR-MS 2/2
General 27/27
Hardsubx 1/1
Hauppage 3/3
MP4 3/3
NoCC 10/10
Options 81/86
Teletext 20/21
WTV 13/13
XDS 34/34

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

Congratulations: Merging this PR would fix the following tests:

  • ccextractor --autoprogram --out=srt --latin1 --quant 0 85271be4d2..., Last passed: Never
  • ccextractor --autoprogram --out=ttxt --latin1 --ucla dab1c1bd65..., Last passed: Never
  • ccextractor --out=srt --latin1 --autoprogram 29e5ffd34b..., Last passed: Never
  • ccextractor --out=spupng c83f765c66..., 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

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.

@DhanushVarma-2
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DhanushVarma-2 commented Mar 10, 2026

@cfsmp3 Addressed all review feedback.
Rust FFmpeg demuxer supports AVC/H.264, HEVC/H.265, CEA-608/708, tx3g, and chapter extraction via rsmpeg. Build system fixes (ENABLE_HARDSUBX, link ordering, compat defines, swresample, bindgen allowlist), code cleanup (dead declarations, variable naming, match arm allocations), squashed to 3 commits. ccxr_dumpchapters is fully implemented shows as binary in diff due to FFI null terminators. VobSub detected but not decoded (known gap). Tested locally on MP4 files, all CI green.

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DhanushVarma-2 commented Mar 10, 2026

Screenshot 2026-03-10 at 6 15 03 PM

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