deviated chapter timecodes?
There are a few programs can extract chapters from DVD with the help from libdvdread (e.g. dvdxchap in ogmtools, mkvmerge in mkvtoolnix). However, the timecodes they extracted seems to deviate gradually. (Every chapter is shorter/earlier by a certain length.)
Here's an example by dvdxchap/mkvmerge (they produce identical output):
CHAPTER01=00:00:00.000
CHAPTER01NAME=Chapter 01
CHAPTER02=00:01:20.633
CHAPTER02NAME=Chapter 02
CHAPTER03=00:05:49.699
CHAPTER03NAME=Chapter 03
CHAPTER04=00:10:26.899
CHAPTER04NAME=Chapter 04
CHAPTER05=00:15:05.833
CHAPTER05NAME=Chapter 05
CHAPTER06=00:20:41.567
CHAPTER06NAME=Chapter 06
CHAPTER07=00:26:06.000
CHAPTER07NAME=Chapter 07
CHAPTER08=00:31:26.800
CHAPTER08NAME=Chapter 08
CHAPTER09=00:32:52.000
CHAPTER09NAME=Chapter 09
CHAPTER10=00:37:19.333
CHAPTER10NAME=Chapter 10
CHAPTER11=00:40:48.100
CHAPTER11NAME=Chapter 11
CHAPTER12=00:44:57.700
CHAPTER12NAME=Chapter 12
CHAPTER13=00:50:09.800
CHAPTER13NAME=Chapter 13
CHAPTER14=00:55:19.000
CHAPTER14NAME=Chapter 14
CHAPTER15=00:59:55.000
CHAPTER15NAME=Chapter 15
CHAPTER16=01:04:31.667
CHAPTER16NAME=Chapter 16
CHAPTER17=01:09:09.000
CHAPTER17NAME=Chapter 17
CHAPTER18=01:13:06.066
CHAPTER18NAME=Chapter 18
CHAPTER19=01:18:28.166
CHAPTER19NAME=Chapter 19
CHAPTER20=01:23:58.000
CHAPTER20NAME=Chapter 20
CHAPTER21=01:29:02.200
CHAPTER21NAME=Chapter 21
CHAPTER22=01:30:48.667
CHAPTER22NAME=Chapter 22
CHAPTER23=01:35:52.667
CHAPTER23NAME=Chapter 23
CHAPTER24=01:40:53.067
CHAPTER24NAME=Chapter 24
CHAPTER25=01:42:05.100
CHAPTER25NAME=Chapter 25
CHAPTER26=01:42:42.333
CHAPTER26NAME=Chapter 26
CHAPTER27=01:47:55.866
CHAPTER27NAME=Chapter 27
CHAPTER28=01:53:08.166
CHAPTER28NAME=Chapter 28
CHAPTER29=01:58:12.633
CHAPTER29NAME=Chapter 29
and one by makemkv (a proprietary software):
CHAPTER01=00:00:00.000
CHAPTER01NAME=Chapter 01
CHAPTER02=00:01:20.713
CHAPTER02NAME=Chapter 02
CHAPTER03=00:05:50.049
CHAPTER03NAME=Chapter 03
CHAPTER04=00:10:27.526
CHAPTER04NAME=Chapter 04
CHAPTER05=00:15:06.739
CHAPTER05NAME=Chapter 05
CHAPTER06=00:20:42.808
CHAPTER06NAME=Chapter 06
CHAPTER07=00:26:07.566
CHAPTER07NAME=Chapter 07
CHAPTER08=00:31:28.686
CHAPTER08NAME=Chapter 08
CHAPTER09=00:32:53.972
CHAPTER09NAME=Chapter 09
CHAPTER10=00:37:21.572
CHAPTER10NAME=Chapter 10
CHAPTER11=00:40:50.548
CHAPTER11NAME=Chapter 11
CHAPTER12=00:45:00.397
CHAPTER12NAME=Chapter 12
CHAPTER13=00:50:12.809
CHAPTER13NAME=Chapter 13
CHAPTER14=00:55:22.319
CHAPTER14NAME=Chapter 14
CHAPTER15=00:59:58.595
CHAPTER15NAME=Chapter 15
CHAPTER16=01:04:35.538
CHAPTER16NAME=Chapter 16
CHAPTER17=01:09:13.149
CHAPTER17NAME=Chapter 17
CHAPTER18=01:13:10.452
CHAPTER18NAME=Chapter 18
CHAPTER19=01:18:32.874
CHAPTER19NAME=Chapter 19
CHAPTER20=01:24:03.038
CHAPTER20NAME=Chapter 20
CHAPTER21=01:29:07.542
CHAPTER21NAME=Chapter 21
CHAPTER22=01:30:54.115
CHAPTER22NAME=Chapter 22
CHAPTER23=01:35:58.419
CHAPTER23NAME=Chapter 23
CHAPTER24=01:40:59.119
CHAPTER24NAME=Chapter 24
CHAPTER25=01:42:11.225
CHAPTER25NAME=Chapter 25
CHAPTER26=01:42:48.495
CHAPTER26NAME=Chapter 26
CHAPTER27=01:48:02.342
CHAPTER27NAME=Chapter 27
CHAPTER28=01:53:14.954
CHAPTER28NAME=Chapter 28
CHAPTER29=01:58:19.725
CHAPTER29NAME=Chapter 29
I checked the content (it's a live concert dvd) and confirmed that the timecodes from makemkv are much more accurate.
Let me know if I need to share parts of / the whole dvd for further debug.