AppleScript and QuickTime frame sequences

Question

Hi all. I've got some movies with foreign subtitles I want to convert to English. However, when I open them with QT Pro and choose the 'Movie Properties' window I see the subtitles are stored as images in a separate VobSub video track (not text).
Biggest challenge here is getting an accurate "cue-in" and "cue-out" time reference for each individual subtitle, so I tried a few off-the-shelf solutions like AVIDemux from SourceForge hoping they might at least give me this info (and leave the OCR translations for me to worry about), but I had nothing but install errors or crashes 100% of the time with this 3rd party software.
AppleScript seemed the logical thing to try and I've got almost no knowledge of it, but here's what I've managed to cobble together after several days of trial and error:
     tell application "QuickTime Player"
       tell document 1
            set SubtitleCount to round (count frames of track 3) -- counts total titles
                              -- seems we need another 'tell' to access each individual frame's info
            tell track 3
                 set FrameStart to time of frame 3
                 set FrameLength to duration of frame 3 -- gives interval before NEXT frame, not time onscreen
            end tell
       end tell
     end tell
     display dialog "Subtitles: " & SubtitleCount & return & "Start: " & FrameStart / 1000 & return & "Length: " & FrameLength / 1000
Obviously the example code is hard-wired to give info for frame 3 only (and eventually needs a looping function), but the SubtitleCount and FrameStart code work perfectly. Unfortunately however, FrameLength simply gives me the time interval between the start of frame 3 and start of frame 4, rather than the required duration on-screen.
For example, suppose from the above code that frame 3 shows a length of 12.92 seconds before the start of the next frame -- but only shows on-screen for 4.7 seconds before being "cued" out again. Obviously something is telling QT Player Pro 7 when to stop displaying this frame. But what? And how can I access this parameter (if it's even possible)?
I'd sure appreciate any suggestions/solutions from the more experienced in this forum. Thanks a lot in advance :-)

Answer 1

Camelot,
How can I poll the duration to see if it is increasing? While it may be a poor solution, given the limited options in QuickTime, this may be the only option.
I seem to have everything else working now and have modified my code as below.
tell application "QuickTime Player"
  activate
  close every window
  new movie recording
  present document 1
  delay 2
  start document 1
          repeat 299 times
                    if document 1 is not playing then
  save
  quit
                              exit repeat
                    else
                              delay 1
                    end if
          end repeat
          try
  stop document 1
  save
  quit
          end try
end tell
Any more help would be greatly appreciated.
Thanks.