Programmable Authoring systems

Early structured authoring tools were not able to allow the authors to express automatic function for handling certain routine tasks. But programmable authoring system has improved in providing powerful functions based on image processing and analysis and embedding program interpreters to use image-processing functions. The capability of this authoring system is enhanced by building user programmability in the authoring tool to perform the analysis and to manipulate the stream based on the analysis results and also manipulate the stream based on the analysis results. The programmability allows the following tasks through the program interpreter rather than manually.

• Return the time stamp of the next frame.
  
• Delete a specified movie segment.
  
• Copy or cut a specified movie segment to the clip board.
  
• Replace the current segment with clip board contents.
  

Multisource Multi user Authoring System

We can have an object hierarchy in a geographic plane; that is some objects may be linked to other objects by position, while others may be independent and fixed in position. We need object data, and information on composing it. Composing means locating it in reference to other objects in time as well as space. Once the object is rendered (rendering here means display of multimedia object on screen) the author can manipulate it and change it's rendering information must be available at the same time for display.

If there are no limits on network bandwidth and server performance, it would be possible to assemble all required components on queue at the right time to be rendered. In Addition to the multi-user composing function, a multi user authoring system must provide resource allocation and scheduling of multimedia objects. This gives raise to a number of synchronization issues.

Synchronization Issues

As multiple servers start writing out the objects to the user workstation, the input must be managed in a temporally intelligent manner and coordinated so that buffers of appropriate streams are managed separately and synchronized for rendering. A composition process manager is essential for this purpose. This problem becomes more complex if some objects must overlap other objects and remain visible. The sequence in which these objects are received and buffered becomes crucial for correct operation.

Another synchronization issue occurs when multiple authors must edit a set of objects sharing common areas on a timeline in a predefined sequence in real time. The objects must be played out to the different users in the proper order. Editing these objects can result in timeline shifts that must be adjusted dynamically.

Finally in a complex composition system, the user may need some specialized capabilities for customizing their environment. A programmable system is highly desirable for such system authoring requirements.