synchronization of subtitles

[senderj]

Read a few guide on inserting sub to DVD. They all have a step to "synchronize" the sub. All the text based subtitle files have start and end time code for each sub line. I don't understand why we still need a synchronization step. Are the time code supposed to be accurate?

[mic]

Different releases, captures etc. can have different start times, plus there are potential fps issues. If you can use as is great, but if they don't match, now you know what to do.:)

[senderj]

What I am trying to do is to use a Chinese srt sub (download) to replace one of the three sub in a R1 DVD. But I was stopped at the sync stage. The sub, as the site said, is 25 fps (although the srt does not have frame number in the time code). The DVD is NTSC. I demux the vob, got 1 m2v, 3 ac3 and 6 sup (with file name containing 20, 21, 22, 23, 24, 25).

First question:
Checking the movie ifo, there are 3 subpic: English (ID 0x20, 0x21), Franch (ID 0x22, 0x23, 0x20) and Spannish (ID 0x24, 0x25, 0x20). I don't understand why 0x20 appears in all sub-pic.

Ignoring this and go ahead to use Subtitle Creater to open the srt and use the 0x20 sup to sync. Second question:

The 2 sub is far out of sync. First thing I check is the starting delay. I compare the start time of line 6, they are 1 second apart. Compare lines at around line 50, they are 10 seconds apart. So it is not the starting delay issue. So I convert the srt from 25 to 29.97 fps, but still the same result. Try to 30fps, same again. Also, the no. of sub line is 2054 and 1981, and the total time has around 10 min. difference. Is sync them line by line the only way out?

[ukendt]

The sub, as the site said, is 25 fps...
There is no support for dl subs.
I believe this is the second time I write this in 1 day....