1.0 Functional Description
CX25870/871
1.3 Device Description
Flicker-Free Video Encoder with Ultrascale Technology
Table 1-20. Composite and Chrominance Magnitude
C and
Composite
Mb
Mwht
Myel
Mcyn
Mgrn
Mmgt
Mred
Mblu
Mblk
Magnitudes
NTSC-M
(volts)
0.286
0
0.444
0.630
0.589
0.589
0.629
0.444
0
NTSC-J (volts)
PAL-B (volts)
0.286
0.300
0
0
0.480
0.470
0.681
0.663
0.636
0.620
0.636
0.620
0.681
0.664
0.480
0.470
0
0
NOTE(S): Mx numbers are the peak-to-peak amplitudes of the subcarrier waveform.
1.3.38 CCIR656 Mode Operation
Data transmitted from MPEG-2 video decoders or various Multimedia Processors
is often done in a format called CCIR656. This format is similar to the CCIR601
in many ways but is unique in that the video sync information is embedded as
codes in the data stream. As a result, no digital HSYNC or VSYNC signals are
required as part of the physical interface between the timing master and slave
devices. Applications for CCIR656 typically include consumer appliances such as
Video CD players, DVD players, set-top boxes, and MPEG add-in cards where
pin counts are limited.
The actual digital CCIR656 input data delivered to the CX25870/871 is
interlaced 4:2:2 YCrCb over eight physical lines. In addition, there are two timing
reference codes, one at the beginning of each video data block (Start of Active
Video, SAV) and one at the end of each video data block (End of Active Video,
EAV). These timing reference values are digital words consisting of a unique
4-word sequence that conveys when the active video starts and ends. The
CCIR656 compliant master device embeds both SAV and EAV codes into the
stream where appropriate.
While in CCIR656 Mode, the CX25870/871 acts as the Slave device (both
clocking and timing). An illustration of this correct connection scheme is shown
in Figure 1-32.
Figure 1-32. CX25870/871 Connection to CCIR656-Compatible Master Device
CX25870/CX871
Composite #1
Luma
27 MHz Clock
CLKI
MPEG2
Decoder
8
Chroma
P[7:0]
4:2:2 YCrCb
Composite #2
100381_060
1-64
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
