Digital computer interface for simulating and transferring CD-I data including buffers and a control unit for receiving and synchronizing audio signals and subcodes

摘要

The present invention provides for at least two levels of buffering in compensating for the delays from and out of the Unix workstation, thus achieving the required timebase correction. At the first level of buffering there is an eight Megabyte memory coupled to the VME bus of the Unix workstation over a disc simulator processor, which is sufficient to store about 45 seconds of audio data. The secondary level of data buffering is provided by an interface board which further buffers an additional 1.5 milliseconds between the first level of buffering and the second level of buffering. The outbound interface of the present invention comprises three separate registers to process the compact disc data when they are retrieved from the digital computer. Each of the registers comprises a plurality of FIFO registers. The first register receives outbound audio samples. The second register receives Q subcode data. The third register receives optionally QRSTUVW or RSTUVW subcode data. Instead of burdening the Unix software with the task of interleaving the subcodes, the present invention manages and manipulates the subcodes with the hardware of the interface. An inbound interface similar to that of the outbound interface is also provided for receiving and storing compact disc data. Thus, the present invention can store and replay compact disc data simultaneously.