16.6. Frame Buffer Application Examples
|Locked Rate Support||Frame Dropping||Frame Repeating||Application Example|
A system with source-synchronous input and outputs (sharing the same clock, or genlocked), with an input frame rate of 60 Hz and an output frame rate of 24 Hz.
The frame buffer implements a triple buffer, providing a regular drop/repeat pattern to ensure that the lower output rate is maintained with minimal perceived jitter in the output video.
Register 10 (Input Frame Rate) should be set to 60 and register 11 (Output Frame Rate) to 24, or any other two short int values to represent the 60:24 ratio.
The frame buffer must be able to drop and repeat frames when input and output rates are locked.
A system with inputs and outputs which are not source-synchronous (no common clock), with an input frame rate of 60 Hz and an output frame rate of 24 Hz.
The frame buffer implements a "triple buffer", providing a variable drop/repeat pattern to accommodate any phase drift seen due to the different clocks.
This is the most common configuration used for video standard conversion applications.
A system with source-synchronous input and outputs (sharing the same clock, or genlocked), with an input frame rate of 50 Hz and an output frame rate of 50 Hz.
This configuration may be useful where the input and output have different burst characteristics, for example a DisplayPort input and an SDI output. The frame buffer implements a "double buffer", providing very little backpressure to the input, while maintaining the required steady rate at the output.