How ffDiaporama work

## Functional principles

Slides are shown one after another, in the order in which they appear in the time line.
The following diagram shows the principles of functioning of slides:

### The slides

On the upper part of the diagram are represented slides A, B, C and D.

- Each slide possesses an entering transition (symbolized on the diagram by a small rectangle labelled T). The transitions don't all have the same duration (symbolized on the diagram by the lengths TA’, TB', etc.): It is indeed possible to define the duration of the entering transition for each slide separately (or to indicate no transition: duration=0).
- Each slide possesses a duration which is appropriate for it (symbolized on the diagram by the lengths B', C', etc.): Some last only a few seconds while others can last several minutes. The durations are expressed in seconds but are not necessarily whole numbers: a slide mightl last 12.234 seconds!
- Each slide is a composite, an assembly of one or more multimedia elements which are animated over time. The animation is realized through shots.
- Each slide can define a new background (bottom of screen).
- Each slide can define a new musical play-list.

Slides which do not define a background use the background defined in a previous slide. So in the following example:

- Slide 1 - Defines a background
- Slide 2 - Does not define a background and therefore uses the background defined by slide 1
- Slide 3 - Does not define a background and therefore uses the background defined by slide 1
- Slide 4 - Defines a background
- Slide 5 - Does not define a background and therefore uses the background defined by slide 4

The same principle applies to the musical play-lists. As long as slides do not define a new play-list, they use the last defined play-list.

### Shots and blocks

The lower part of the diagram represents the slide C.

- Each slide comprises one or more shots. The shots are represented on the diagram by rectangles C1, C2, C3, etc. …
- Each shot has its own duration (symbolized on the diagram by the lengths C1 ', C2 ', C3 ', etc.). Some shots can last only seconds while others can last several minutes. Some shots can have a duration of zero. (The durations are expressed in seconds but are not necessarily whole numbers: A shot can very well last 12.234 seconds!)
- The shots can contain several multimedia objects. The multimedia objects are integrated into blocks which can be of three types: title (containing only text), images (or photos), or video.
- The shots are transparent. This means that if the image does not fill the whole screen, the background (see bottom of screen) will appear.

Remarks:

- The shots define the arrangement of blocks (multimedia objects) at any given moment.
- The shot animations are generated by the transformation of these arrangements from one shot to another.

Specifically, if in the foreground, an image occupies the whole screen, and then occupies only a small part of the screen in the following shot, then the animation will consist of the transformation of the image of the whole screen (previous shot) into that small part of the screen (following shot).
Example:

- Shot 1: Image using the whole screen: Duration=2 seconds.
- Shot 2: Image using only the bottom right screen quarter: Duration 3 seconds.
- Shot 3: Image again using the whole screen: Duration=2 seconds.

- Result: the image will be shown on the whole screen for 2 seconds, will shrink gradually over 3 seconds towards the right lower quarter of the screen, and then will grow again for 2 seconds until it once more occupies the whole screen.
- The slide will end as soon as the image has reached the position defined in shot 3.

Remarks:

- The transformations are gradual: in the example you will see the image being gradually reduced.
- The transformations are made over the whole duration of the following shot.

The definition of the objects in each block can vary from one shot to another. The following example shows three different definitions from the same block:

- 1st shot: The image is complete.
- 2nd shot: The image is re-framed on the statue.
- 3rd shot: The image is re-framed on the pedestrians.

If we apply these definitions to the previous 3 shots:

- The complete image will be shown on all the screen for 2 seconds, then will be reduced gradually over 3 seconds by zooming in on the statue in the right lower quarter of the screen, then will grow over 2 seconds until it once more occupies the whole screen while moving towards the pedestrians.

Remarks:

- ffDiaporama can manage up to several hundreds slides in a single project.
- Each slide can consist of tens of shots.
- Each slide can contain tens of blocks.
- Blocks can be visible on some shots and invisible on other.

### The "Visible" property of blocks and the management of the breaks

Blocks have a visible/invisible property. In the following example, the image is inserted 3 times (in 3 different blocks) into the same slide.

- The first block defines the whole image filling the whole screen
- The second block defines the image re-framed on the statue and positioned in an ellipse at the right of the screen
- The third block defines the image re-framed on the pedestrians and also positioned in an ellipse at the right of the screen

The statue and the pedestrians have their visibility property set to invisible on the 1st shot.
Then the statue becomes visible on the 2nd shot.
Finally, the statue once more becomes invisible on the 3rd shot and the pedestrians become visible.
Result :

- For 2 seconds, the 1st shot is shown and we see only the whole image which occupies all the screen
- Over the next 2 seconds, the statue appears
- Over a further 2 seconds, the statue is replaced by the pedestrians

This example is really very simple, because it is also possible to animate the appearance and the disappearance of blocks.
Indeed, as shown previously, animations are generated by the transformation of the arrangement from one shot to another.
So, if on the 1st shot, the statue occupied the left lower quarter of the screen rather than the same position as on the 2nd shot, then instead of simply appearing for 2 seconds on the 2nd shot, it would appear by growing out of the left lower quarter of the screen.
You should note that videos are paused when they are invisible.
Therefore a video can be displayed for several seconds in the 1st shot, then be made invisible and thus paused in a 2nd shot, then be visible in a 3rd shot and resume playing, from where it stopped at the end of the 1st shot.

### Remark:

The total duration of the project is not equal to the sum of the durations of the slides because the transitions make the slides overlap: Two slides of 10 seconds, each with a transition of 1 second, will give a total duration for the project of 19 seconds (and not 20 seconds)!

## See also

- Index of the ffDiaporama WIKI

ffDiaporama 1.0