The following links represent three explorations into how best to make a time-lapse movie out of a linear movie using a sample of three hours (out of a total of ~ 20 hours) of linear video taken with a system capable of video taping the visual field of a microscope. The purpose here is to facilitate decision making as to which method produces the most useful balance of animation versus movie duration in terms of best practice in pedagogy and scientific visualization.
Method: VHS Tape source was digitized using a Sony DVMC-DA1 to convert analog signals from a VHS player to digital data and captured with iMovie 3 on a MacOS X computer as NTSC DV files in a QuickTime container. Thus, the 3 hours of video became 20 2GB files that were assembled as a single composite movie (saved with dependencies) to be used as the prototype source.
Using QuickTime Player Pro, which is scriptable, an Applescript was written to go through the composite movie and take samples at intervals. The three prototype movies linked to below represent three combinations of interval and sample size. I = interval (in frames) and S = sample (in seconds) Since the movie frame rate is 29.7, the interval time can be estimated with frames/30.
NOTES:
The Applescript:
set the increment_amount to 1200
set the delay_amount to 0.01
set the requested_seconds to 0.1
set the source_movie to "Composite Clip.mov"
tell application "QuickTime Player"
activate
try
if not (exists movie 1) then error "No movies are open."
stop every movie
-- CHECK FOR THE CORRECT VERSION
set QT_version to (QuickTime version as string)
set player_version to (version as string)
if (QT_version is less than "5.0") or Â
(player_version is less than "5.0") then
error "This script requires QuickTime 5.0 or greater." & Â
return & return & Â
"Current QuickTime Version: " & QT_version & return & Â
"Current QuickTime Player Version: " & player_version
end if
-- CHECK FOR QUICKTIME PRO
if QuickTime Pro installed is false then
set the target_URL to "http://www.apple.com/quicktime/download/"
display dialog "This script requires QuickTime Pro." & return & return & Â
"If this computer is currently connected to the Internet, " & Â
"click the ÒUpgradeÓ button to visit the QuickTime Website at:" & Â
return & return & target_URL buttons {"Upgrade", "Cancel"} default button 2
ignoring application responses
tell application "Finder"
open location target_URL
end tell
end ignoring
error number -128
end if
repeat
set the movie_length to the duration
set the current_time to the current time
if the current time is equal to the movie_length then exit repeat
tell movie source_movie
step forward by the increment_amount
delay the delay_amount
select movie source_movie at current_time to (current_time + (requested_seconds * (time scale)))
copy
end tell
tell movie 2
paste
end tell
end repeat
on error error_message number error_number
if the error_number is not -128 then
beep
display dialog error_message buttons {"Cancel"} default button 1
end if
end try
end tell
Future Development: