Playlist mechanism for specification of complex memory objects

DETAILED DESCRIPTION OF INVENTION The memory playlist is a data structure that defines the component objects, as well as the algorithm for combining those objects into a complex composite media object or data stream.
The memory playlist contains pointers to data objects, as well as control information to enable looping, branching, and subroutines within the playlist.
The memory playlist may be modified dynamically at run-time by the application, i.
e.
, while it is being played.
This data structure can be specified as a memory object to be processed by a device in the IBM OS/2 Multimedia Presentation Manager/2.
TM.
(MMPM/2).
TM.
System.
This innovation, although not limited to, is specifically adapted for OS/2.
TM.
data processing environments.
The memory playlist structure is formulated by the application, and is not intended as a high-level scripting or presentation language.
Computer, programming and software terms, and other included designations throughout this specification, are used as commonly intended in their related fields, the general meanings of any of which can be found in IBM's Dictionary of Computing.
The format of the memory playlist is similar to that of machine instructions.
Each instruction in the playlist is of a fixed format, consisting of a 32-bit operation code and three 32-bit operands.
The playlist comprises an array of playlist instructions, set forth as in FIG.
1A, wherein each includes an opcode and operands 1, 2 and 3.
FIG.
1B summarizes the different memory playlist instructions and is descriptive of the operations of each.
The operations or instructions include DATA, BRANCH, LOOP, CALL, RETURN, EXIT, NOP, MESSAGE and CUEPOINT.
This memory playlist is particularly useful for playing synthesized audio.
With the memory playlist, audio objects can be played in succession from one or more memory buffers accessed through the DATA operation.
FIG.
2 is an exemplary illustration for playback from, in this case four, multiple memory buffers to achieve the effect of a "talking" clock