cx25840 Conexant Systems, Inc., cx25840 Datasheet - Page 91

• Manufacturer Part Number: cx25840
• Description: Video Decoder And Broadcast Audio
• Manufacturer: Conexant Systems, Inc.

CX25840/1/2/3 Data Sheet
Table 3-28. 43 Locking Register Values for Common Audio Sample Rate
102284B
8/3/05
13.5 M
13.5 M
13.5 M
13.5 M
14.75 M
14.75 M
14.75 M
14.75 M
12.27 M
12.27 M
12.27 M
12.27 M
Video Pixel
Rate
48 k
96 k
32 k
44.1 k
48 k
96 k
32 k
44.1 k
48 k
96 k
32 k
44.1 k
Audio Sample
Rate
numbers by a common integer such that all modes have similar loop update rates. The
video pixels and audio samples columns show the minimum ratio of whole pixel to
whole sample counts. However, because the actual clocks are multiples of the video
pixel and audio sample rates, and because the video count can be specified to 3-bit
fractional granularity, the logic does not have to wait for that long to measure the ideal
ratio.
will achieve the desired ratio. The VID_COUNT register value assumes an 8x pixel
clock and a 21-bit integer, 3-bit fractional number. The AUD_COUNT register value
assumes a 384 x sample rate clock.
The table entries show the exact ratio, and the event that generates an error happens
faster than the field rate of 60 Hz. (NTSC square pixel with 32 kHz audio would have
a worst-case update rate of 40 Hz. However, because the AUD_COUNT integer is
divisible by eight, and there are still three bits of resolution in the VID_COUNT
register, both numbers could be divided by eight to reduce the update frequency to
320 Hz.)
Table 3-28
1,125
1,125
2,250
4,500
7,375
7,375
7,375
147,500
818,181
818,181
2,454,543
272,727
Video Pixels
shows the minimum values of AUD_COUNT and VID_COUNT that
4
8
8
147
24
48
16
441
3,200
6,400
6,400
980
Conexant
Audio Samples
0x1193F8
0x08CAF8
0x0D2EF8
0x057E38
0x0733B8
0x0733B8
0x0733B8
0x0900A8
0x0C7BFD
0x0C7BFD
0x257407
0x04294F
Recommended
VID_COUNT
Detailed Functional Description
0x01B8F
0x023FF
0x095FF
0x05FFF
0x02FFF
0x02FFF
0x047FF
0x017FF
0x02957
0x04AFF
0x095FF
0x016F7
Recommended
AUD_COUNT
3-65