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Posted: **Mon Dec 08, 2008 4:46 pm**

Hi Folks,

How can I control the current frame of a QT movie in RunRev?

I'd like to be able to monitor an input and make the movie jump to the corresponding frame. Can this be done?

Thanks

Jim H

Posted: **Mon Dec 08, 2008 6:29 pm**

Hi Jim,

this is a tricky one.
the player gives you the duration of the movie and the timescale. The duration is the length of the movie in seconds, if you divide the duration by the timescale. Timescale is typically 600 in Quicktime, but not necessarily so. The timescale indicates in how many intervalls a second is split in the movie. Depends on the type of movie you use. To get at the length of a frame in revolution you need to know the framerate, the framerate you can look up in the Quicktime Player-> info.

Lets assume you have a movie that plays at 25 frames per sec and it has the standard timescale of 600 then you take the duration (as provided by the Player object in Rev) and divide it by 24. This is the duration of a frame at 25 frames per second in a timescale of 600 (600/25=24): that gives you the number of frames.
The other way around is:

multiply 24 by the framenumber and tell the player object to set the curenttime to that number. That goes to the frame number you want.

This is only true if the framerate is 25 and the timescale 600.
If you are on a mac then you could open the movie of interest in the quicktime player and then you open the scripteditor to run this applescript

Code: Select all

tell application "QuickTime Player"
	tell document 1 -- make shure its a movie
		set theDuration to the duration
		set theTimeScale to the time scale
		tell track 1 -- make shure track 1 is a video track
			set theFrames to count of frames
			set theFrameLength to duration of frame 1
			set y to the duration of every frame
		end tell
	end tell
end tell

display dialog "length in seconds: " & theDuration / theTimeScale & return & "framerate: " & theTimeScale / theFrameLength

I have tried to explain this from a different angle here

http://www.mail-archive.com/use-revolut ... 98200.html

just try in your project to advance the currenttime by 24 and see if it is the next frame, that is kind of a low tech solution, but it often works.

hth
Bernd

Posted: **Tue Dec 09, 2008 12:04 am**

try this in a button

Code: Select all

on mouseUp
put the currenttime of player "myPlayer" into tTemp
add 24 to tTemp
set the currenttime of player "myPlayer" to tTemp
end mouseUp

If this advances your player by one frame then you know that the frame-duration of one frame is 24. So your movie has a framerate of 25 assuming the timescale is 600
If you dont get there post a little more of your problem and we can work it out.
cheers
Bernd

Posted: **Tue Dec 09, 2008 12:51 am**

Thanks Bernd,

That's doing something but it seems a little unpredictable - after a few clicks it stops advancing. However, I put a "answer tTemp" at the end and now it advances every click - but of course I don't want a dialog coming up all the time!

Strange that it doesn't work so well without the answer call.

Jim

Posted: **Tue Dec 09, 2008 1:19 am**

Hmmm - well on inspection actually the playhead was advancing and very occasionally the frame would jump forward.

I've tinkered with things a bit and its a little better - but still not nearly so good as simply dragging the playhead.

Here's what I've got so far:

Code: Select all

on mouseDown
  put the currenttime of player "myPlayer" into tTemp 
  add 24 to tTemp 
  set the currenttime of player "myPlayer" to tTemp 
  put tTemp into fld "myFrame"
end mouseDown

on mouseStillDown
  
  add 24 to tTemp 
  set the currenttime of player "myPlayer" to tTemp 
  put tTemp into fld "myFrame"
end mouseStillDown

In the midst of writing this I went back and tried it again. The trick is to have the movie playing - then it works perfectly!!

Thanks a million Bernd.

Jim H

Posted: **Tue Dec 09, 2008 1:55 am**

Jim,
it is a little jerky with the mouseDown or mouseStillDown so I tried this in the script of the player

Code: Select all

constant cFrame = 24
local tCurrent

on arrowKey pDirection -- up|down|left|right
    if pDirection = "right" then
        put the currenttime of player "myPlayer" into tCurrent
        send "NextFramePlease" to me in 5 milliseconds
    end if
    if pDirection is "left" then 
        put the currenttime of player "myPlayer" into tCurrent
        send "prevFramePlease" to me in 5 milliseconds
    end if
end arrowKey

on NextFramePlease
        add cFrame to tCurrent
        set the currenttime of player "myPlayer"  to tCurrent
end NextFramePlease

on prevFramePlease
    subtract cFrame from tCurrent
    set the currenttime of player "myPlayer"  to tCurrent
end prevFramePlease

this works really nice for me with the arrowKeys
Anyway I thought you wanted to jump to a frame so it was just to find out the duration of the frame.
There are a lot of things one can do with the player and then there are some things that dont work so well. Let's see...
regards
Bernd

Posted: **Tue Dec 09, 2008 9:19 am**

Hi Jim,

you really should check Trevors WONDERFUL Enhanced QuickTime External:
http://www.mangomultimedia.com/develope ... ncedqt.php

Beneath other goodies it will let you query the framerate of movies e.g.

Best

Klaus

Posted: **Tue Dec 09, 2008 9:55 am**

Thanks for all the help. I'll check out the externals but to be honest I'm getting what I need from:

Code: Select all

        set the currenttime of player "myPlayer" to fld "myField"

It jumps about a little but I'm guessing that this is mostly to do with my sensor inputting rogue readings - some filtering to do I suspect.

Cheers

Jim H

LiveCode Forums.

Control frames of a QuickTime movie

Control frames of a QuickTime movie