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參數(shù)資料
| 型號(hào)： | ADV7188 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Multiformat SDTV Video Decoder with Fast Switch Overlay Support |
| 中文描述： | 標(biāo)清多格式視頻解碼器支持快速開關(guān)重疊 |
| 文件頁數(shù)： | 28/112頁 |
| 文件大小： | 943K |
| 代理商： | ADV7188 |
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ADV7188
Rev. 0 | Page 28 of 112
0
COARSE
CURRENT
FINE
CURRENT
DATA
PRE-
PROCESSOR
(DPP)
ADC
SDP
WITH DIGITAL
FINE CLAMP
CLAMP CONTROL
ANALOG
VIDEO
INPUT
Figure 14. Clamping Overview
DCT[1:0] Digital Clamp Timing, Address 0x15 [6:5]
The clamp timing register determines the time constant of the
digital fine clamp circuitry. It is important to realize that the
digital fine clamp reacts very quickly since it is supposed to
immediately correct any residual dc level error for the active
line. The time constant of the digital fine clamp must be much
quicker than the one from the analog blocks.
By default, the time constant of the digital fine clamp is adjusted
dynamically to suit the currently connected input signal.
Table 35. DCT Function
DCT[1:0]
Description
00
Slow (TC = 1 sec).
01
Medium (TC = 0.5 sec).
10 (default)
Fast (TC = 0.1 sec).
11
Determined by the ADV7188, depending on
the I/P video parameters.
DCFE Digital Clamp Freeze Enable, Address 0x15 [4]
This register bit allows the user to freeze the digital clamp loop
at any time. It is intended for users who would like to do their
own clamping. Users should disable the current sources for
analog clamping via the appropriate register bits, wait until the
digital clamp loop settles, and then freeze it via the DCFE bit.
0 (default)—The digital clamp is operational.
1—The digital clamp loop is frozen.
LUMA FILTER
Data from the digital fine clamp block is processed by three sets
of filters. The data format at this point is CVBS for CVBS input
or luma only for Y/C and YPrPb input formats.
Luma antialias filter (YAA). The ADV7188 receives video
at a rate of 27 MHz. (For 4× oversampled video, the ADCs
sample at 54 MHz, and the first decimation is performed
inside the DPP filters. Therefore, the data rate into the
ADV7188 is always 27 MHz.) The ITU-R BT.601 recommends
a sampling frequency of 13.5 MHz. The luma antialias
filter decimates the oversampled video using a high quality,
linear phase, low-pass filter that preserves the luma signal
while at the same time attenuating out-of-band components.
The luma antialias filter has a fixed response.
Luma shaping filters (YSH). The shaping filter block is a
programmable low-pass filter with a wide variety of re-
sponses. It can be used to selectively reduce the luma video
signal bandwidth (needed prior to scaling, for example).
For some video sources that contain high frequency noise,
reducing the bandwidth of the luma signal improves visual
picture quality. A follow-on video compression stage may
work more efficiently if the video is low-pass filtered.
The ADV7188 has two responses for the shaping filter: one
that is used for good quality CVBS, component, and S-VHS
type sources, and a second for nonstandard CVBS signals.
The YSH filter responses also include a set of notches for
PAL and NTSC. However, it is recommended to use the
comb filters for YC separation.
Digital resampling filter. This block is used to allow dynamic
resampling of the video signal to alter parameters such as
the time base of a line of video. Fundamentally, the resampler
is a set of low-pass filters. The actual response is chosen by
the system with no requirement for user intervention.
Figure 16 through Figure 19 show the overall response of all
filters together. Unless otherwise noted, the filters are set into a
typical wideband mode.
Y-Shaping Filter
For input signals in CVBS format, the luma shaping filters play
an essential role in removing the chroma component from a
composite signal. YC separation must aim for best possible
crosstalk reduction while still retaining as much bandwidth
(especially on the luma component) as possible. High quality
YC separation can be achieved by using the internal comb filters
of the ADV7188. Comb filtering, however, relies on the
frequency relationship of the luma component (multiples of the
video line rate) and the color subcarrier (Fsc). For good quality
CVBS signals, this relationship is known; the comb filter
algorithms can be used to separate out luma and chroma with
high accuracy.
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| ADV7188BSTZ | 功能描述:IC DECODER VID MULTIFORM 80LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 編碼器，解碼器，轉(zhuǎn)換器 系列:- 產(chǎn)品變化通告:Development Systems Discontinuation 26/Apr/2011 標(biāo)準(zhǔn)包裝:1 系列:- 類型:編碼器 應(yīng)用:DVB-S.2 系統(tǒng) 電壓 - 電源，模擬:- 電壓 - 電源，數(shù)字:- 安裝類型:- 封裝/外殼:模塊 供應(yīng)商設(shè)備封裝:模塊 包裝:散裝 其它名稱:Q4645799 |
| ADV7189 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Multiformat SDTV Video Decoder |
| ADV7189B | 制造商:AD 制造商全稱:Analog Devices 功能描述:Multiformat SDTV Video Decoder |
| ADV7189BBSTZ | 功能描述:IC VIDEO DECODER SDTV 80-LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 編碼器，解碼器，轉(zhuǎn)換器 系列:- 產(chǎn)品變化通告:Development Systems Discontinuation 26/Apr/2011 標(biāo)準(zhǔn)包裝:1 系列:- 類型:編碼器 應(yīng)用:DVB-S.2 系統(tǒng) 電壓 - 電源，模擬:- 電壓 - 電源，數(shù)字:- 安裝類型:- 封裝/外殼:模塊 供應(yīng)商設(shè)備封裝:模塊 包裝:散裝 其它名稱:Q4645799 |
| ADV7189BBSTZ268H | 制造商:AD 制造商全稱:Analog Devices 功能描述:Multiformat SDTV Video Decoder |
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