CECI EST UN
TEST POUR LA
RECHERCHE



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.



About structure for media (M)
M1
C1

M1
- Filetype (video or sound)
- Timeline Layout Color
(orange or purple)

« Color » : This is ALSO a dynamically computed method, with following formula
-If position of media M is even in timeline description: color is orange
- If position of media M is odd in timeline description: color is purple

As a consequence, when we do manipulation such as on previous slide, Media description does NOT change either !
Only timeline changes from (M1, M2, M3, M4) to (M1, M2, M4, M3)

M2

M1
C1

C2

M4

M3
C3

C4
M4

C5
M3

2.5 What about other objects ?
All other “visual” objects in Alexandra should also be “ported” to use relative time TR:
-

comments (“bubbles”)
“black cursors”
“sommaire” comments

reason is always the same, if a user has commented a video and you move the video, you
should move the comment with the video, and so on...