Appendix E HDTV Output Mode
CX25870/871
E.6 Allowable Resolutions
Flicker-Free Video Encoder with Ultrascale Technology
E.6 Allowable Resolutions
Table E-5 summarizes the most popular HD resolutions or ATSC video formats
supported by the CX25870/871.
Table E-5. CX25870/CX25871 HDTV Supported Formats
A c t i v e
Format
(H x V )
Governing
Standards
Input Data Format
(can be muxed or nonmuxed)
O u t p u t A s p e c t
Ratio
Frame Rate
1920x1080 = 1080i
(contains trilevel syncs)
SMPTE-274M
&
EIA-770.3
15, 16, or 24 bit RGB or
16 or 24 bit Digital YPBPR
16 : 9
16 : 9
16 : 9
30 Hz.
interlaced
1280x720 = 720p
(contains trilevel syncs)
SMPTE-296M
&
EIA-770.3
15, 16, or 24 bit RGB or
16 or 24 bit Digital YPBPR
60 Hz.
noninterlaced
720x480 = 480p
(does not contain trilevel
syncs)
SMPTE-293M
15, 16, or 24 bit RGB or
16 or 24 bit Digital YPBPR
60 Hz.
noninterlaced
Conceivably, any HD format with a clock less than or equal to 80 MHz can be
displayed with the RASTER_SEL[1:0] = 00 option. This flexibility allows the
CX25870/871 to receive resolutions not yet standardized. All HDTV Output
Mode resolutions will generate the new WSS wide screen format that provides an
aspect ratio of 16:9 yielding a movie-theatre like viewing experience.
When the encoder is in HDTV Output Mode, the internal FIFO and flicker
filter blocks are bypassed. Therefore, the Y/PB/PR and R/G/B video outputs do
not have any flickering filtering nor any overscan compensation applied to them.
For 480p, 720p, and other progressive input formats, the lack of flicker filtering
causes no degradation whatsoever in the video output quality as compared to the
digital input. For 1080i and other interlaced input formats, the lack of flicker
filtering sets off the appearance of minor flickering in screen regions with small
vertical dimensions.
The lack of overscan compensation in HDTV Output Mode results in the outer
horizontal and vertical edges of the active image to appear behind the bezel of the
television. This annoyance can be overcome by the insertion of a solid colored
border around the active image itself by the data master in the digital domain.
E-12
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
