Synchronization techniques for multimedia data streams

A multimedia data processing system comprising:

• a personal computer having a memory for storing a multimedia application program and a multitasking operating system, and a processor for executing said application program and operating said multimedia data processing system under said operating system;
• master stream means connected to said personal computer for producing a master data stream in response to commands from said multimedia application program, said master stream means including a master source device for producing first media data, a master target device for receiving said first media data from said master source device, and master stream handling means for producing a master data stream in which said first media data flows along a first path from said master source device to said master target device;
• slave stream means connected to said personal computer for producing a slave data stream in response to commands from said multimedia application program, said slave stream means including a slave source device for producing second media data, a slave target device for receiving said second media data from said slave source device, and slave stream handling means for producing a slave data stream in which said second media data flows along a second path from said slave source device to said slave target device, said second path being completely separated from said first path;
• said master target device and said slave target device producing, in response to receiving said master data stream and said slave data stream, two different time-dependent humanly-perceivable outputs;
• and
• synchronizing means operable under said operating system for synchronizing said slave data stream with said master data stream to maintain time-dependency between said outputs of said target devices, said synchronizing means comprising
• a synchronization manager;
• first means for periodically storing timing pulses in said memory, each timing pulse indicating current time of said master data stream relative to when said master data stream was started;
• notifying means for notifying said synchronization manager each time one of said timing pulses is stored in said memory;
• second means for periodically storing, in said memory, indications of current time of said slave data stream;
• said synchronization manager includes third means, operative in response to receiving notification from said notifying means, for comparing current time of said master data stream with current time of said slave data stream and selectively notifying said slave stream handling means;
• and
• said slave stream handling means further includes fourth means, operative in response to receiving notification from said synchronization manager, for transmitting second media data to said slave target device.