For those of us who want more than what the Random/ Shuffle playback mode offers, the
DVD specification has the virtual machine command "Rnd" which can generate a random
number between 1 and a specified value. The maximum range is from 1 to 65535. The
following example illustrates how to play these sixteen chapters randomly and not
repeating the last three chapters already played in the random sequence. These are
the additional steps we need to perform:
1. We add a cell command to each chapter. The cell command executes the
postcommand section of the title PGC. The postcommand simply links to our random
2. We need to create an additional PGC labeled "Random" whose precommand section
contains the instructions to generate the random chapter (the chapter number is
stored in GPRM0). The last three chapters played are stored in GPRM1, GPRM2, and
GPRM3. When a new random value is generated, it is compared to one of these three
values. If the chapter is already played back, the random generation process is
repeated until a good value is produced. The contents of GPRM1, GPRM2, and GPRM3
are updated to reflect the most recent three chapters.
3. To separate the functions of random generation and the actual selection of the
chapters to play back, we need to create another PGC labeled "RandomRouting" as
following. The idea is that we can apply changes to our random generation algorithms
within the precommand section of the PGC labeled "Random". The result value in GPRM0
is then passed to the PGC labeled "RandomRouting" to select the appropriate chapter
to play back.
If everything is set up correctly, we should see the following link relationships as
in the scenario below. To add or modify virtual commands, position the cursor at the
appropriate Cell, Pre, or Post icons and double click to display the Simulation
window. Otherwise, we can proceed to the Layout window to generate the VIDEO_TS
The following display from the Simulation window allows the modification of virtual
machine commands in the random generation engine (double click on the precommand
section of the PGC label "Random").
The best training and learning approach with Scenarist is by doing practical examples
which make sense to you as a DVD author. So unleash the power of Scenarist with the
best guides you will not be able to find anywhere else at this introductory price.
You will be glad that buying these survival guides is one of the best investments
you ever made. The series of guides in Acrobat PDF format contain more information
on what presented online. To order your guides today, click on the following icon.