Texas Instruments TMS320C64x DSP Benutzerhandbuch
Video Input Filtering
Video Capture Port
3-26
SPRU629
VCTL2 is a VSYNC (vertical sync) input, then a long field is always detected.
(Even if VCYSTOPn is set to the last active line, VCOUNT usually increments
past VCYSTOPn + 1 while it counts the vertical front porch lines that occur
prior to VSYNC active.)
(Even if VCYSTOPn is set to the last active line, VCOUNT usually increments
past VCYSTOPn + 1 while it counts the vertical front porch lines that occur
prior to VSYNC active.)
3.5
Video Input Filtering
The video input filter performs simple hardware scaling and resampling on
incoming 8-bit BT.656 or 8-bit Y/C data. Filtering hardware is always disabled
during 10-bit or raw data capture modes. For proper filter operation, the
channel’s EXC bit in VCxCTL must be cleared to 0 (embedded timing refer-
ence codes used) and the CAPEN input must not go inactive during the active
video window.
incoming 8-bit BT.656 or 8-bit Y/C data. Filtering hardware is always disabled
during 10-bit or raw data capture modes. For proper filter operation, the
channel’s EXC bit in VCxCTL must be cleared to 0 (embedded timing refer-
ence codes used) and the CAPEN input must not go inactive during the active
video window.
3.5.1
Input Filter Modes
The input filter has four modes of operation: no-filtering,
½
scaling, chrominance
resampling, and
½
scaling with chrominance resampling. Filter operation is
determined by the CMODE, SCALE, and RESMPL bits of VCxCTL.
Table 3–10 shows the input filter mode selection. When 8-bit BT.656 or Y/C
capture operation is selected (CMODE = x00), scaling is selected by setting
the SCALE bit and chrominance resampling is selected by setting the
RESMPL bit. If 8-bit BT.656 or Y/C capture is not selected (CMODE
capture operation is selected (CMODE = x00), scaling is selected by setting
the SCALE bit and chrominance resampling is selected by setting the
RESMPL bit. If 8-bit BT.656 or Y/C capture is not selected (CMODE
≠
x00),
filtering is disabled.
Table 3–10. Input Filter Mode Selection
VCxCTL Bit
CMODE
RESMPL
SCALE
Filter Operation
x00
0
0
No filtering
x00
0
1
½
scaling
x00
1
0
Chrominance resampling (full scale)
x00
1
1
½
scaling with chrominance resampling
x01
x
x
No filtering
x10
x
x
No filtering
x11
x
x
No filtering