2.0 Functional Description
Fusion 878A
2.3 Y/C Separation and Chroma Demodulation
PCI Video Decoder
2-4
Conexant
100600B
2.3 Y/C Separation and Chroma Demodulation
illustrates Y/C separation and chroma decoding. Band-pass and notch
filters are implemented to separate the composite video stream. The filter
responses are illustrated in
. The optional chroma comb filter is
implemented in the vertical scaling block. See
schematically describes the filtering and scaling operations.
In addition to the Y/C separation and chroma demodulation illustrated in
, the Fusion 878A also supports chrominance comb filtering as an
optional filtering stage after chroma demodulation. The chroma demodulation
generates baseband I and Q (NTSC) or U and V (PAL/SECAM) color difference
signals.
For S-Video operation, the digitized luma data bypasses the Y/C separation
block completely and the digitized chrominance is passed directly to the chroma
demodulator.
For monochrome operation, the Y/C separation block must be disabled and the
saturation registers (SAT_U and SAT_V) are set to 0.
Figure 2-2. Y/C Separation and Chroma Demodulation for Composite Video
Notch Filter
Band Pass Filter
Low Pass Filter
Low Pass Filter
sin
cos
Y
U
V
Composite
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