Timeline with multiple media files
This document gives some insight about implementation of slides 7 and 8 of NewScreen.ppt

1 How are new media (sound or video) added ?
We have 2 new buttons that appear on right colum of carousel (see slide 21)

2 Important concepts – Main changes
2.1 Absolute time vs relative time
Today, we position cursors (C) on the timeline and give them a certain timecode (T).
What we see page 7 is that when we move a piece of the timeline, existing cursors will move
with it. It has to be so because if you have synced a slide with a certain video, moving the
video and not moving the slide with it would make no sense: it would unsync the slide.
This means:
-

each cursor is associated to a certain media (M)

-

each cursor has a timecode which is relative to that media : TR. It is important to
understand that this timecode is not the absolute timecode in the presentation: TA.
(Until now, there was no difference to be made, but from now on, you will have to
“separate” the 2 concepts).

and

The picture below shows the relationship between TR and TA

c
TR
TA
TA = TR + (duration of all other media positionned “before” the cursor)

2.2 Consequences: what needs to be changed
In the “old” implementation of Alexandra, you have C(T) [This means a cursor object
contains a timecode]. You have to rewrite the new implementation so you have C (M, TR).
This is the main technical change.