GS4910B GENNUM [Gennum Corporation], GS4910B Datasheet - Page 65

• Manufacturer Part Number: GS4910B
• Description: HD/SD/Graphics Clock and Timing Generator with GENLOCK
• Manufacturer: GENNUM [Gennum Corporation]

Table 3-9: Encoding Scheme for AFS_Reset_Window
3.7.2.1 Audio to Video Clock Phasing
NOTE: ‘X’ signifies ‘don’t care.’ The bit setting will be ignored.
AFS_Reset_Window
(address 31h)
(default)
1XX
000
001
010
011
fs = 32kHz
0.044
0.084
0.166
0.329
0.654
The important aspect of the audio to video phase relates to the way in which the
AFS pulse is used to reset the audio clock dividers so as to line up the leading edge
of the audio clocks with the leading edge of the H Sync pulse on line 1 of the first
field in the audio frame sequence. The AFS pulse is further discussed in
Section 3.8.2 on page
625i 50 Format
For the 48kHz sampling rate, the audio to video phase relationship for 625/50i
reference signals is provided by the device in accordance with the EBU
recommended practice R83-1996. The start of an audio frame (fs clock) will align
with the 50% point of the H sync input of line 1 of each video frame (+/- the
allowable drift specified in
525i 59.94 Format
For 525/59.94 NTSC reference signals, the device will observe the 5-frame
phase-relationship inherent with this video standard, aligning the audio clocks with
the 50% point of the H sync input of line 1 on every fifth frame (+/- the allowable
drift specified in
The number of audio sample clocks during a video frame is shown in
for 32, 44.1, and 48kHz audio sampling frequencies.
36655 - 2
April 2006
fs = 44.1kHz
0.033
0.062
0.121
0.239
0.475
Table
68.
3-9).
Window Tolerance (us)
Table
fs = 48 kHz
0.030
0.057
0.220
0.437
3-9).
0.112
GS4911B/GS4910B Data Sheet
(enable_384fs = 1)
fs = 96 kHz
0.030
0.057
0.220
0.437
0.112
(enable_384fs = 0)
fs = 96 kHz
Table 3-10
0.044
0.084
0.166
0.329
0.654
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