[FFmpeg-user] Subs start at zero instead of what IDX says

[Mark Filipak]

Hi All!

I've done two jobs now and both times the dvd_subtitle coder starts at
0:00.000, contrary to what the IDX files show. I know that FFmpeg is
reading the IDXs because the intervals between subtitles are correct.

Apparently, dvd_subtitle is intentionally subtracting the 1st subtitle's
time from _every_ entry in the IDX. I can find no other plausible
explanation.

The options are '-map 1:s:0 -c:s dvd_subtitle' where
source 0 is video,
source 1 is IDX,
source 2 is SUB.
I've tried loading the IDX last and I've tried loading only the IDX and
only the SUB. All combinations exhibit this issue.

I've not run into this before because I've previously OCRed subtitles
via subtitleedit and saved as SRT. The procedure that avoids OCR is this:
Code an MKV with PGS subtitles and throwaway video.
Extract the PGS as SUP via mkvextract.
Convert the SUP to IDX+SUB via bdsup2sub++.

I reiterate that the resulting IDXs are correct, with correct times.
The dvd_subtitle coder is subtracting the 1st subtitles time from
_every_ subtitle time.

Can you help?

Thanks--Mark.