In a similar manner, it can be calculated that the programming array is in this case:
SUBADDRESS
0x04
REGISTER NAME
csc_r11
VALUE
SUBADDRESS
0x0F
REGISTER NAME
csc_g32
VALUE
1000 0001
1101 0101
0000 0000
0000 0000
0000 0110
0010 1001
0000 0100
0000 0000
0000 0100
1000 0000
0000 0100
0000 0000
1000 0000
1011 1011
0000 0111
0100 0010
0000 0000
0000 0000
0001 0100
1010 1110
1000 1011
0001 0100
0x05
csc_r12
0x10
csc_b11
0x06
csc_r21
0x11
csc_b12
0x07
csc_r22
0x12
csc_b21
0x08
csc_r31
0x13
csc_b22
0x09
csc_r32
0x14
csc_b31
0x0A
csc_g11
csc_g12
csc_g21
csc_g22
csc_g31
0x15
csc_b32
0x0B
0x16
csc_offs1
csc_offs12
csc_offs23
csc_offs3
0x0C
0x17
0x0D
0x18
0x0E
0x19
4.5 Clip/Scale/Multiplier (CSM)
There are limits on the code range of the video data if sampled according to ITU or SMPTE standards. In other words,
the full 10-bit range [0:1023] is not used to represent video pixels. For example, typically 64 decimal is the lowest code
allowed to represent a video signal and corresponds to the blanking level. Similarly for Y, typically the maximum code
is 940 decimal. Excursions outside this range can be the result of digital video processing.
THS8200 can handle such instantaneous excursions in either of two ways: by limiting the input codes to
programmable max/min values, or by allowing such excursions to occur.
Depending on which approach is chosen, the user can scale up the video data in the CSM to make sure the full-scale
dynamic range of the DAC is used for optimal performance when using limiting. Alternatively, the instantaneous
excursions outside the code range can be output by the DAC in the analog output signal (allowing super-white/black
in analog output) when this clipping is disabled.
The CSM block allows the user to specify the behavior of THS8200 with such reduced-swing input video codes. It
consists of the following:
1. an optional clipping of the input video data at a high and low limit, where the limits are individually
programmable per channel
2. a downward shift of the input video data, where the shift amount is individually programmable per channel
3. a multiply (magnitude scaling) function of the video data, where the multiplier coefficient is individually
programmable per channel.
4.5.1 Clipping
Clipping (limiting) of the video input data can be turned on or off on a per-channel basis, and selectively at the high
and/or low end, by programming the csm_<gy,rcr,bcb>_<high,low>_clip_on registers. The high/low clipping values
can be programmed on a per-channel basis using registers csm_clip_<gy,rcr,bcb>_<high,low>.
Figure 4–5 shows a typical situation to clip ITU-R.BT601 sampled video signals.
4–8
TI [ TEXAS INSTRUMENTS ]
