ADV601JS Analog Devices, ADV601JS Datasheet - Page 7

• Manufacturer Part Number: ADV601JS
• Description: Low Cost Multiformat Video Codec
• Manufacturer: Analog Devices

THE PROGRAMMABLE QUANTIZER
This block quantizes the filtered image based on the response
profile of the human visual system. In general, the human eye
cannot resolve high frequencies in images to the same level of
accuracy as lower frequencies. Through intelligent “quantiza-
tion” of information contained within the filtered image, the
ADV601 achieves compression without compromising the visual
quality of the image. Figure 7 shows the encode and decode
data formats used by the quantizer.
Figure 8 shows how a typical quantization pattern applies over
Mallat block data. The high frequency blocks receive much larger
quantization (appear darker) than the low frequency blocks (appear
lighter). Looking at this figure, one sees some key point concerning
quantization: (1) quantization relates directly to frequency in
Mallat block data and (2) levels of quantization range widely from
high to low frequency block. (Note that the fill is based on a log
formula.) The relation between actual ADV601 bin width factors
and the Mallat block fill pattern in Figure 8 appears in Table II.
REV. 0
40
37
41
38
28
39
29
36
31
34
32
35
19
20
27
25
22
26
33
30
23
18
10
11
13
16
14
21
17
24
9
Cr COMPONENT
Figure 8. Typical Quantization of Mallat Data Blocks (Graphed)
Cb COMPONENT
7
4
8
15
12
5
6
3
1
2
Y COMPONENT
–7–
LOW
WAVELET
NUMBER
15.0 BIN
DATA
9.7
Figure 7. Programmable Quantizer Data Flow
6.10 1/BW
QUANTIZATION OF MALLAT BLOCKS
SIGNED
SIGNED
8.8 BW
UNSIGNED
UNSIGNED
1/BW
BW
QUANTIZER - ENCODE MODE
QUANTIZER - DECODE MODE
SIGNED
SIGNED
0
15.17 DATA
23.8 DE-QUANTIZED
WAVELET DATA
0.5
TRNC
ADV601
SAT
HIGH
15.0 BIN
NUMBER
9.7
WAVELET
DATA