XSUB: Difference between revisions

From MultimediaWiki
Jump to navigation Jump to search
No edit summary
(spelling)
Line 9: Line 9:
The header starts with timing information in the format (27 bytes, no terminating zero):
The header starts with timing information in the format (27 bytes, no terminating zero):
  [HH:MM:ss.mmm-HH:MM:ss.mmm]
  [HH:MM:ss.mmm-HH:MM:ss.mmm]
Then, encoded as 16 bit little endian except for the colour entries, follow:
Then, encoded as 16 bit little-endian except for the color entries, follow:
  width of encoded image
  width of encoded image
  height of encoded image
  height of encoded image
Line 17: Line 17:
  y coordinate of bottom right subtitle corner
  y coordinate of bottom right subtitle corner
  length of the RLE data
  length of the RLE data
  four colour entries (red, green, blue, eight bits per component, unsigned)
  four color entries (red, green, blue, eight bits per component, unsigned)


Width, height and coordinates probably all must be a multiple of 2.
Width, height and coordinates probably all must be a multiple of 2.
It is unclear what the behaviour is if the coordinates are not consistent with width and height, the encoder does not produce such files.
It is unclear what the behavior is if the coordinates are not consistent with width and height, the encoder does not produce such files.


After this follows the RLE-encoded data.
After this follows the RLE-encoded data.
Line 26: Line 26:
This is processed 4 bits at a time, big-endian bitstream order (lowest byte address first, within that byte highest bits first).
This is processed 4 bits at a time, big-endian bitstream order (lowest byte address first, within that byte highest bits first).


Encoding is n bits run length followed by 2 bits color (index into four-colour palette in header), where n can be 2, 6, 10, or 14 (yes, it is a very weird and probably suboptimal encoding).
Encoding is n bits run-length followed by 2 bits color (index into four color palette in header), where n can be 2, 6, 10, or 14 (yes, it is a very weird and probably suboptimal encoding).


n can be determined via the number of leading zeros:
n can be determined via the number of leading zeros:
Line 34: Line 34:
     4 - 5          10          16 -  63
     4 - 5          10          16 -  63
     6 - 7          14          64 - 255
     6 - 7          14          64 - 255
     > 7            14          must be == 0 and means the remainder of the row has this colour
     > 7            14          must be == 0 and means the remainder of the row has this color


After each row the bitstream is byte-aligned
After each row the bitstream is byte-aligned.


[[Category:Subtitle Formats]]
[[Category:Subtitle Formats]]

Revision as of 14:34, 5 August 2007

XSUB is the subtitle format used in DivX 6 files. Each packet consists of a header and after that RLE-encoded data. The header starts with timing information in the format (27 bytes, no terminating zero):

[HH:MM:ss.mmm-HH:MM:ss.mmm]

Then, encoded as 16 bit little-endian except for the color entries, follow:

width of encoded image
height of encoded image
x coordinate of top left subtitle corner
y coordinate of top left subtitle corner
x coordinate of bottom right subtitle corner
y coordinate of bottom right subtitle corner
length of the RLE data
four color entries (red, green, blue, eight bits per component, unsigned)

Width, height and coordinates probably all must be a multiple of 2. It is unclear what the behavior is if the coordinates are not consistent with width and height, the encoder does not produce such files.

After this follows the RLE-encoded data.

This is processed 4 bits at a time, big-endian bitstream order (lowest byte address first, within that byte highest bits first).

Encoding is n bits run-length followed by 2 bits color (index into four color palette in header), where n can be 2, 6, 10, or 14 (yes, it is a very weird and probably suboptimal encoding).

n can be determined via the number of leading zeros:

leading zeros   |    n      | possible length values
    0 - 1            2            1 -   3
    2 - 3            6            4 -  15
    4 - 5           10           16 -  63
    6 - 7           14           64 - 255
    > 7             14           must be == 0 and means the remainder of the row has this color

After each row the bitstream is byte-aligned.