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參數資料
| 型號： | ADV7175A |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
| 中文描述： | 高品質，10位，數字無線電咨詢委員會，601到PAL / NTSC制式視頻編碼器 |
| 文件頁數： | 30/52頁 |
| 文件大小： | 629K |
| 代理商： | ADV7175A |
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ADV7175A/ADV7176A
–30–
REV. B
T he ADV7175A/ADV7176A supports closed captioning, conforming to the standard television synchronizing waveform for color
transmission. Closed captioning is transmitted during the blanked active line time of Line 21 of the odd fields and Line 284 of even
fields.
Closed captioning consists of a 7-cycle sinusoidal burst that is frequency and phase locked to the caption data. After the clock run-in
signal, the blanking level is held for two data bits and is followed by a L ogic L evel “1” start bit. 16 bits of data follow the start bit.
T hese consist of two 8-bit bytes, seven data bits and one odd parity bit. T he data for these bytes is stored in closed captioning Data
Registers 0 and 1.
T he ADV7175A/ADV7176A also supports the extended closed captioning operation, which is active during even fields, and is en-
coded on scan Line 284. T he data for this operation is stored in closed captioning extended Data Registers 0 and 1.
All clock run-in signals and timing to support closed captioning on Lines 21 and 284 are generated automatically by the ADV7175A/
ADV7176A. All pixels inputs are ignored during Lines 21 and 284.
FCC Code of Federal Regulations (CFR) 47 Section 15.119 and EIA608 describe the closed captioning information for Lines 21 and
284.
T he ADV7175A/ADV7176A uses a single buffering method. T his means that the closed captioning buffer is only one byte deep,
therefore there will be no frame delay in outputting the closed captioning data unlike other 2-byte deep buffering systems. T he data
must be loaded at least one line before (Line 20 or Line 283) it is outputted on Line 21 and Line 284. A typical implementation of
this method is to use
VSYNC
to interrupt a microprocessor, which will in turn load the new data (two bytes) every field. If no new
data is required for transmission you must insert zeros in both the data registers; this is called NULLING. It is also important to load
“control codes,” all of which are double bytes on Line 21, or a T V will not recognize them. If you have a message like “Hello World”
which has an odd number of characters, it is important to pad it out to an even number to get “end of caption” 2-byte control code to
land in the same field.
12.91
m
s
S
T
A
R
T
P
A
R
I
T
Y
P
A
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T
Y
D0–D6
D0–D6
10.003
m
s
33.764
m
s
50 IRE
40 IRE
FREQUENCY = F
SC
= 3.579545MHz
AMPLITUDE = 40 IRE
REFERENCE COLOR BURST
(9 CYCLES)
7 CYCLES
OF 0.5035 MHz
(CLOCKRUN-IN)
10.5
6
0.25
m
s
TWO 7-BIT + PARITY
ASCII CHARACTERS
(DATA)
27.382
m
s
BYTE 0
BYTE 1
Figure 46. Closed Captioning Waveform (NTSC)
APPE NDIX 2
CLOSE D CAPT IONING
相關PDF資料 |
PDF描述 |
|---|---|
| ADV7175AKS | High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
| ADV7176A | High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
| ADV7176AKS | High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
| ADV7176A* | High Quality. 10-Bit. Digital CCIR-601 to PAL/NTSC Video Encoder |
| ADV7175 | Integrated Digital CCIR-601 YCrCb to PAL/NTSC Video Encoder |
相關代理商/技術參數 |
參數描述 |
|---|---|
| ADV7175AKS | 制造商:AD 制造商全稱:Analog Devices 功能描述:High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
| ADV7175KS | 制造商:AD 制造商全稱:Analog Devices 功能描述:Integrated Digital CCIR-601 YCrCb to PAL/NTSC Video Encoder |
| ADV7176 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Integrated Digital CCIR-601 YCrCb to PAL/NTSC Video Encoder |
| ADV7176A | 制造商:AD 制造商全稱:Analog Devices 功能描述:High Quality, 10-Bit, Digital CCIR-601 to PAL/NTSC Video Encoder |
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