3.0 Digital Processing and Functionality
3.1 Video
Bt860/861
Multiport YCrCb to NTSC/PAL /SECAM
3.1.6 Subcarrier Phasing (SC_H Phase)
For PAL and NTSC video formats, the subcarrier phase is set to 0 on the leading
edge of the analog vertical sync every four (NTSC) or eight (PAL) fields, unless
the SC_RESET bit is set to a logical 1. This is true for both interlaced and
non-interlaced outputs. In addition, the subcarrier phase can be adjusted by the
PHASE_OFF register. Each LSB change of PHASE_OFF corresponds to a
360 / 256 degree change in the phase.
Setting SC_RESET to 1 is useful when the subcarrier phase at the end of a
color field sequence is significantly different from 0.
3.1.7 Noninterlaced Operation
When programmed for noninterlaced master mode, the Bt860/861 always
displays the odd field. The FIELD signal stays low to indicate that the field is
always odd. A 30 Hz offset should be subtracted from the color subcarrier
frequency while in NTSC mode so the color subcarrier phase will be inverted
from field to field. Transition from interlaced to noninterlaced in master mode
occurs during odd fields to prevent synchronization disturbance.
NOTE: Consumer VCRs can record noninterlaced video with minor noise
artifacts, but special effects (e.g., scan >2x) may not function properly.
3-12
Conexant
D860DSA
CONEXANT [ CONEXANT SYSTEMS, INC ]
