2.0 Functional Description
Fusion 878A
2.4 Video Scaling, Cropping, and Temporal Decimation
PCI Video Decoder
2-20
Conexant
100600B
When changing the programming in the temporal decimation register, 0x00
should be loaded first, and then the decimation value. This ensures that the
decimation counter is reset to 0. If 0 is not loaded first, the decimation may start
on any field or frame in the sequence of 60 (or 50 for PAL/SECAM). On
power-up, this preload is not necessary because the counter is internally reset.
When decimating fields, the FLDALIGN bit in the TDEC register can be
programmed to choose whether the decimation starts with an odd field or an even
field. If the FLDALIGN bit is set to logical 0, the first field dropped during the
decimation process will be an odd field. Conversely, setting the FLDALIGN bit to
logical 1 causes the even field to be dropped first in the decimation process.
TDEC = 0x9E Decimation is performed by fields. Thirty fields are out-
put per 60 fields of video, assuming NTSC decoding.
This value outputs every other field (every odd field)
of video starting with field 1 in frame 1.
TDEC = 0x01 Decimation is performed by frames. One frame per 50
frames of video is skipped, assuming PAL/SECAM de-
coding.
TDEC = 0x00 Decimation is not performed. Full frame rate video is out-
put by the Fusion 878A.