Abstract: Disclosed are apparatus and methods for synchronized presentation of analog and digital data by applying a common synchronization scheme to both types of data. Digital data is "streamed" by transferring the data in blocks from a source to a series of memory buffers, where it accumulates for subsequent transfer to an output device driver. The control module responsible for data streaming periodically reports a temporal location within the presentation represented by the data. A supervisory module designates one of the control modules a "master", and periodically compares the values reported by the various other control modules against that reported by the master. If a comparison exceeds a threshold tolerance value associated with each control module, a sync pulse is delivered to that control module, causing it to correct the synchronization mismatch.

Abstract: Disclosed are apparatus and methods for synchronized interleaving of multimedia data arriving from distinct sources. The invention independently buffers the incoming data streams and determines the amount of presentation time associated with each data element or byte of each data stream. The invention then draws data from the buffers at varying rates that reflect these differences, continuously presenting the withdrawn data to an interleaving module at data-streaming rates that reflect equivalent presentation-time rates. The invention also includes means for disabling synchronization when one type of data is streamed at a particularly high or low rate, resulting in buffer overload (with either the high-rate data or all data other than that transferred at the low rate).

Abstract: Disclosed are methods and apparatus that facilitate the introduction of filters, converters and effects into an active multimedia stream without interruption of the presentation. A control module or sequence permits such introduction only after verifying the presence of a sufficient supply of buffered presentation data. Responding to a user's request for introduction of a filter, the invention first determines whether its immediate implementation would cause interruption, and either introduces the filter, converter or effect into the data stream as backlogged data continues to be presented, or postpones its introduction until sufficient buffered data does exist.