free-d Virtual Studio System Operators Guide - Vinten Radamec

Data structures
The following sections describe the data structures within the non-volatile storage of the free-d processor
unit. The storage consists of a Flash EEPROM holding up to 64 Kbytes of data, comprising a database of
marker positions for one or more studios and a database of camera and lens calibration values for one or
more cameras. Since the space available must be shared between these databases, the maximum size of
each is dependent on the size of the other. The data capacity of the EEPROM is sufficient for
approximately 4000 markers (corresponding to perhaps five medium-sized studios); the maximum
number of cameras for which data may be stored is 256.
Data tables
There are five types of data table presently defined:
• Camera data pointers
• Studio data pointers
• Camera and lens data
• Studio data
• Marker data
Camera data pointers
This table consists of 256 16-bit values (512 bytes) starting at EEPROM address 0x0000. Each 16-bit
value represents a pointer to an area of EEPROM at which data for a particular camera is stored; the
pointers are stored most-significant-byte first. The index into the table is the 8-bit 'Camera ID' which is
received from the camera encoded in its serial digital video signal.
If camera data is present for a particular Camera ID, then the appropriate entry in the table (at address
0x0000 + 2 * Camera_ID) contains the address within the EEPROM at which the Camera and lens data
table is stored. If no data is present for that camera then the table entry contains the value 0xFFFF. Two
or more entries in the table may point to the same camera and lens data.
Studio data pointers
This table consists of 256 16-bit values (512 bytes) starting at EEPROM address 0x0200. Each 16-bit
value represents a pointer to an area of EEPROM at which data for a particular studio is stored; the
pointers are stored most-significant-byte first. The index into the table is the 8-bit 'Studio ID' which is
selected by the user either from the front-panel switches on the free-d processor unit or via the serial data
interface.
If studio data is present for a particular Studio ID, then the appropriate entry in the table (at address
0x0200 + 2 * Studio_ID) contains the address within the EEPROM at which the Studio Data table is
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