Subtitles:

This chapter gives a short introduction on handling and processing subtitles with transcode and related programs.

- DVD subtitle overlay mode with -J extsub

- generating subtitle files with subrip

- adding custom subtitles with -J subtitler

DVD subtitle overlay mode

transcode provides a filter plugin filter_extsub.so for elementary DVD subtitle rendering in connection with -x vob. Use it with

transcode [...] -J extsub=<options>

The option string looks as follows (all options default to 0):

s:h:t:f:w:a:b:p:q

- s subtitle track id (0-31)
  Use tcprobe -H N with N>1 to find out if subtitle any packs are available in the program stream.

- h offset of subtitle with respect to bottom of frame in rows.
  Subtitles are placed at the bottom of the frame. Try this option to shift them up or down.

- t global display start time correction in msec.
  If you feel, subtitles are displayed not timely, adjust it with this option. This will affect all subtitles.

- f fast rendering, i.e., no anti-aliasing (0=off,1=on).
  Anti-aliasing of the font is performed by default. Switch it of (1) if your font is tiny and messed up by this feature.

- w render on post-processing (0=off, 1=on).
  Setting this option to 1 will render the subtitle on post-processing instead of pre-processing. This may improve subtitle quality but makes no sense after extensive resizing of the frame.

- a graylevel value a (0-255).
- b graylevel value b (0-255).
  Make another subtitle color visible with full intensity equal to 255. May lead to fatter fonts.

- p assign subtitle color p [0-3] to graylevel value a.
- q assign subtitle color q [0-3] to graylevel value b.
  Shuffle the color assignment by choosing another subtitle color between 0 and 3. Useful for black fonts on white background.

Example (1) changing color assignment:

- -J extsub

  this one looks not as expected without any further options.

- -J extsub=0:0:0:0:0:0:0:1:2

  shuffle the font color assignment using 1:2 looks like this, but has an ugly 3D effect.

- -J extsub=0:0:0:0:0:0:0:1:3

  shuffle the color assignment using 1:3 looks better, but shows white shadows that make the font fatter but blurry

- -J extsub=0:0:0:0:0:0:0:2:3

  shuffle the color assignment using 2:3 seems to be perfect. Nice and smooth looking letters.

- -J extsub=0:0:0:1:0:0:0:2:3

  for comparison, we switch off anti-aliasing, see the difference?

Example (2) adding another white color:

- -J extsub

  this one looks already perfect without any options.

- -J extsub=0:0:0:1

  same as above with-out ant-aliasing.

- -J extsub=0:0:0:0:0:0:255

  We make switch another color to full intensity (white) to make the subtitle appear fatter, maybe too much.

- -J extsub=0:0:0:1:0:0:255

  The above fat one without anti-aliasing.

generating subtitle files

Please find some documentation on Arne Driescher's subrip program in the `contrib/subrip/` directory or visit the project page for more information.

generating custom subtitles

Please find some documentation on Jan Panteltje's subtitler plugin in the `filter/subtitler/` directory or visit the project page for more information.

Last modified: Thu May 16 12:52:34 CEST 2002