GS2972 Datasheet, PDF (38/125 Pages) Semtech Corporation – 3G/HD/SD-SDI Serializer with Complete SMPTE Audio & Video Support

4.3.2 CEA 861 Timing
The GS2972 extracts timing information from externally provided HSYNC, VSYNC, and
DE signals when CEA 861 timing mode is selected by setting DETECT_TRS = LOW and
TIM_861 = HIGH.
Horizontal sync (H), Vertical sync (V), and Data Enable (DE) timing must be provided via
the H/HSYNC, V/VSYNC and F/DE input pins. The host interface register bit H_CONFIG
is ignored in CEA 861 input timing mode.
The GS2972 determines the EIA/CEA-861 standard and embeds EAV and SAV TRS
words in the output serial video stream.
Video standard detection is not dependent on the HSYNC pulse width or the VSYNC
pulse width and therefore the GS2972 tolerates non-standard pulse widths. In addition,
the device can compensate for up to ±1 PCLK cycle of jitter on VSYNC with respect to
HSYNC and sample VSYNC correctly.
Note 1: The period between the leading edge of the HSYNC pulse and the leading edge
of Data Enable (DE) must follow the timing requirements described in the EIA/CEA-861
specification. The GS2972 embeds TRS words according to this timing relationship to
maintain compatibility with the corresponding SMPTE standard.
Note 2: When CEA 861 standards 6 & 7 [720(1440)x480i] are presented to the GS2972,
the device embeds TRS words corresponding to the timing defined in SMPTE ST 125 to
maintain SMPTE compatibility.
CEA 861 standards 6 & 7 [720(1440)x480i] define the active area on lines 22 to 261 and
285 to 524 inclusive (240 active lines per field). SMPTE ST 125 defines the active area on
lines 20 to 263 and 283 to 525 inclusive (244 lines on field 1, 243 lines on field 2).
Therefore, in the first field, the GS2972 adds two active lines above and two active lines
below the original active image. In the second field, it adds two lines above and one line
below the original active image.
The CEA861 Timing Formats are summarized in Table 4-4. and are shown in Figure 4-9
to Figure 4-19.
Table 4-4: CEA861 Timing Formats
Format
4
5
6&7
19
20
21&22
16
31
32
33
34
Parameters
H:V:DE Input Timing 1280 x 720p @ 59.94/60Hz
H:V:DE Input Timing 1920 x 1080i @ 59.94/60Hz
H:V:DE Input Timing 720 (1440) x 480i @ 59.94/60Hz
H:V:DE Input Timing 1280 x 720p @ 50Hz
H:V:DE Input Timing 1920 x 1080i @ 50Hz
H:V:DE Input Timing 720 (1440) x 576 @ 50Hz
H:V:DE Input Timing 1920 x 1080p @ 59.94/60Hz
H:V:DE Input Timing 1920 x 1080p @ 50Hz
H:V:DE Input Timing 1920 x 1080p @ 23.94/24Hz
H:V:DE Input Timing 1920 x 1080p @ 25Hz
H:V:DE Input Timing 1920 x 1080p @ 29.97/30Hz
GS2972 3G/HD/SD-SDI Serializer with Complete
SMPTE Audio & Video Support
Final Data Sheet Rev. 9
GENDOC-047479 September 2013
www.semtech.com
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