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Difference between revisions of "Timed track formats"

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Uses frames for timings.
 
Uses frames for timings.
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(Appears to be basically the PowerDivX format, but using seconds instead of frames.)
  
 
== MPEG-4 Timed Text (.ttxt) ==
 
== MPEG-4 Timed Text (.ttxt) ==
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Currently has low resolution timings. Simple format. Could be extended usefully.
 
Currently has low resolution timings. Simple format. Could be extended usefully.
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 +
(Appears to be basically the MicroDVD format, but using seconds instead of frames.)
  
 
== RealText (.rt) ==
 
== RealText (.rt) ==
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Currently has pixel-based positioning. Simple format. Could be extended usefully.  
 
Currently has pixel-based positioning. Simple format. Could be extended usefully.  
  
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== Gloss Subtitle (.gsub) ==
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Couldn't find any information on this format.
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== SubStation Alpha (.ssa) ==
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* http://www.matroska.org/technical/specs/subtitles/ssa.html
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Pretty verbose. Has some pixel-based positioning. Has some rather subtle syntax of the kind that typically results in buggy implementations.
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== Advanced SubStation Alpha (.ass) ==
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Even more complicated version of  SubStation Alpha.
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== SubViewer (.sub*) ==
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* http://wiki.videolan.org/SubViewer
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 +
Simple format. Uses "[br]" for line breaks. Could be extended usefully.
  
  

Revision as of 01:12, 27 April 2010

Lists of formats:

Requirements:

  • We need to use time for timings, not frames, because the same file might apply to multiple versions of the same video, with different frame rates.
  • For a similar reason, any positioning needs to be relative to the frame, not absolute (in pixels)

(Extensions marked * below are shared by multiple formats.)

AQTitle (.aqt)

Uses frames for timings.

JACOSub (.jss)

Pretty complicated.

Kate

Binary format with text components, making it hard to hand-edit. The text components seem pretty verbose.

MicroDVD (.sub*)

Uses frames for timings.

(Appears to be basically the PowerDivX format, but using seconds instead of frames.)

MPEG-4 Timed Text (.ttxt)

Pretty complicated. Seems to be formatting-centric. Has some pixel-based positioning. Difficult to hand-edit.

MPSub (.sub*)

Relative timings, which can be hard to hand-edit correctly. Could be extended, though most useful extensions would not be backwards-compatible (e.g. adding a new timing format).

Ogg Writ

Binary format, nigh on impossible to hand-edit.

Phoenix Subtitle (.pjs)

  • No spec or demo file found

Uses frames for timings according to wikipedia.

PowerDivX (.psb)

Currently has low resolution timings. Simple format. Could be extended usefully.

(Appears to be basically the MicroDVD format, but using seconds instead of frames.)

RealText (.rt)

Supports a number of features that aren't necessary. Could probably be used as the basis for a new similar format.

SAMI (.smi)

Probably has complicated legacy parsing requirements. Would be difficult to extend in a backwards-compatible way.

Structured Subtitle Format (.ssf)

Couldn't find any information on this format.

SubRip (.srt)

Currently has pixel-based positioning. Simple format. Could be extended usefully.

Gloss Subtitle (.gsub)

Couldn't find any information on this format.

SubStation Alpha (.ssa)

Pretty verbose. Has some pixel-based positioning. Has some rather subtle syntax of the kind that typically results in buggy implementations.

Advanced SubStation Alpha (.ass)

Even more complicated version of SubStation Alpha.

SubViewer (.sub*)

Simple format. Uses "[br]" for line breaks. Could be extended usefully.


Other formats

CMML and SMIL are not listed above since they don't appear to be subtitle formats so much as timed media mixing formats.