12.1.1 Video Timing Parameter Definitions
The following is a list of the typical input video timing parameters and their definitions.
Active Lines Per Frame (ALPF)Number of lines in a frame containing displayable data. This is a subset of the TLPF
Active Pixels Per Line (APPL)Number of pixel clocks in a line containing displayable data. This is a subset of the TPPL
Horizontal Back Porch (HBP) BlankingNumber of blank pixel clocks after Horizontal Sync but before the first active pixel. HBP times are in reference to the leading (active) edge of the respective sync signal
Horizontal Front Porch (HFP) BlankingNumber of blank pixel clocks after the last active pixel but before horizontal sync
Horizontal Sync (HS)Timing reference point that indicates the start of the horizontal interval (line). The absolute reference point is defined by the active edge of the HS signal. This active edge is the reference from which all horizontal blanking parameters are measured
Total Lines (Active and Inactive) Per Frame (TLPF)Defines the vertical period (or frame time) in lines
Total Pixel Per Line (TPPL)Horizontal line period in pixel clocks. Total number of active and inactive pixel clocks per line
Vertical Back Porch (VBP) BlankingNumber of blank lines after Vertical Sync but before the first active line
Vertical Front Porch (VFP) BlankingNumber of blank lines after the last active line but before vertical sync
Vertical Sync (VS)Timing reference point that indicates the start of the vertical interval (frame). The absolute reference point is defined by the active edge of the VS signal. This active edge is the reference from which all vertical blanking parameters are measured