feat(mp4): add dvdsub/VobSub support to FFmpeg MP4 demuxer

[cfsmp3]

Summary

• Wire existing vobsub_decoder (OCR bitmap subtitle decoder) into the FFmpeg MP4 demuxer path
• Adds support for dvdsub tracks in MP4 containers, which were previously unsupported in the FFmpeg path

Changes

• mp4.rs: Add DvdSub track type, detect AV_CODEC_ID_DVD_SUBTITLE, buffer packets for end-time calculation
• mp4_rust_bridge.c: 3 new functions wrapping vobsub_decoder API (init, process, free)
• mp4_rust_bridge.h: Declarations
• CMakeLists.txt: 3 --undefined linker flags for bridge symbols

Test plan

Tested on 1f3e951d516b.mp4 (dvdsub in MP4):

• GPAC: 5405 bytes
• FFmpeg + this patch: 5405 bytes, byte-identical

With this change, the FFmpeg path is a strict superset of GPAC across all 36 MP4/MOV/M4V samples tested:

• 12 samples: byte-identical to GPAC
• 1 sample: FFmpeg extracts 51KB that GPAC cannot (ad9f9e03240e.m4v)
• 1 sample: timing-only diff (~2ms, FFmpeg upstream av_rescale_q rounding)
• 22 samples: no captions in either

[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 e4443a7...:

Report Name	Tests Passed
Broken	9/13
CEA-708	1/14
DVB	2/7
DVD	3/3
DVR-MS	2/2
General	22/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	76/86
Teletext	20/21
WTV	13/13
XDS	31/34

Your PR breaks these cases:

• ccextractor --in=ts c83f765c66...

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 --autoprogram --out=ttxt --latin1 --ucla --xds 8e8229b88b..., Last passed:

  Test 9262

• ccextractor --out=ttxt --latin1 001dd8cdf7..., Last passed:

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• ccextractor --out=srt --latin1 4d4e938ef6..., Last passed:

  Test 8738

• ccextractor --service 1 --out=txt --no-bom --no-rollup ea83ff7bcb..., Last passed:

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• ccextractor --service 1 --out=txt f17524b53f..., Last passed:

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• ccextractor --service 1 --out=txt 80848c45f8..., Last passed:

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• 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:

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• ccextractor --service 1 --out=sami da904de35d..., Last passed:

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• ccextractor --service 1 --out=ttxt da904de35d..., Last passed:

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• ccextractor --service 1[EUC-KR] b5d6aad89f..., Last passed:

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• ccextractor --service 1[EUC-KR] --no-rollup b5d6aad89f..., Last passed:

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• ccextractor --service all da904de35d..., Last passed:

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• ccextractor --service all[EUC-KR] b5d6aad89f..., Last passed:

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• ccextractor --service 1,2[UTF-8],3[EUC-KR],54 --out=txt da904de35d..., Last passed:

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• ccextractor --autoprogram --out=srt --latin1 f1422b8bfe..., Last passed:

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• ccextractor --autoprogram --out=srt --latin1 d41b53b504..., Last passed:

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• ccextractor --stdout --quiet --no-fontcolor 79a51f3500..., Last passed:

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• ccextractor --stdout --quiet --no-fontcolor 767b546f96..., Last passed:

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

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• ccextractor --autoprogram --out=ttxt --latin1 99e5eaafdc..., Last passed:

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• ccextractor --autoprogram --out=ttxt --latin1 --ucla 7aad20907e..., Last passed:

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

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• ccextractor --autoprogram --out=ttxt --latin1 01509e4d27..., Last passed:

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

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• ccextractor --myth c83f765c66..., Last passed:

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• ccextractor --in=raw fb79021542..., Last passed:

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

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

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

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• ccextractor --xmltv=3 --out=null 96efd279cf..., Last passed:

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• ccextractor --datapid 2310 --autoprogram --out=srt --latin1 e639e54550..., Last passed:

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• ccextractor --autoprogram --out=ttxt --xds --latin1 --ucla 85058ad37e..., Last passed:

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• ccextractor --autoprogram --out=srt --latin1 --ucla b22260d065..., Last passed:

  Test 9262

• ccextractor --autoprogram --out=ttxt --latin1 --ucla --xds 7f41299cc7..., Last passed:

  Test 9262

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 e4443a7...:

Report Name	Tests Passed
Broken	9/13
CEA-708	1/14
DVB	3/7
DVD	3/3
DVR-MS	2/2
General	22/27
Hardsubx	1/1
Hauppage	3/3
MP4	3/3
NoCC	10/10
Options	81/86
Teletext	20/21
WTV	13/13
XDS	31/34

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 --autoprogram --out=ttxt --latin1 --ucla --xds 8e8229b88b..., Last passed:

  Test 9263

• 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 --out=ttxt da904de35d..., Last passed:

  Test 8943

• 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 f1422b8bfe..., Last passed:

  Test 9209

• ccextractor --autoprogram --out=srt --latin1 d41b53b504..., Last passed:

  Test 8611

• ccextractor --stdout --quiet --no-fontcolor 79a51f3500..., Last passed:

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• ccextractor --stdout --quiet --no-fontcolor 767b546f96..., Last passed:

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• ccextractor --autoprogram --out=ttxt --latin1 132d7df7e9..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=ttxt --latin1 99e5eaafdc..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=srt --latin1 b22260d065..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=ttxt --latin1 --ucla 7aad20907e..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=ttxt --latin1 01509e4d27..., Last passed:

  Test 9263

• 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

• ccextractor --autoprogram --out=ttxt --xds --latin1 --ucla 85058ad37e..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=srt --latin1 --ucla b22260d065..., Last passed:

  Test 9263

• ccextractor --autoprogram --out=ttxt --latin1 --ucla --xds 7f41299cc7..., Last passed:

  Test 9263

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.