GS2972 Datasheet, PDF (58/125 Pages) Semtech Corporation – 3G/HD/SD-SDI Serializer with Complete SMPTE Audio & Video Support

4.7.17.1 525-Line Audio Sample Distribution
As per the SMPTE ST 272 standard, the following sample distribution allows the
embedding of 16 channels (4 audio groups) of 24-bit sampled audio into the HANC of
525-line based video formats.
The sample distribution is established for Group One and then offset by one line for each
subsequent group. The sample distribution is as follows (start line is 12):
{[3]^(10+G),([4],[3]¹⁵)¹⁵,[4],[3]^(11-G),[0],[3]^(3+G),([4],[3]¹⁵)¹⁵,[4/3],[3]¹²,[4],[3]^(4-G),[0]}⁵
[#] = Number of samples / line
[4/3] = One line with either 3 or 4 samples depending on five-frame sequence
(#) _{= Number of times to repeat the sequence. When this # is 0, no samples are inserted}
G = Audio group number from 1 to 4
{…}⁵ = 5-frame sequence as shown in Table 4-12:
Table 4-12: GS2972 SD Audio Five Frame Sequence Sample Count
Frame
1
2
3
4
5
Number of Samples
1602
1601
1602
1601
1602
The following tables show the audio sample distribution for each of the four audio
groups.
Each distribution has 525 lines.
Each distribution has 1602 samples or 1601 samples, based on the frame number in the
five-frame sequence.
When 1602 samples are required in a frame, the [4/3] term represents a line with four
samples.
When 1601 samples are required in a frame, the [4/3] term represents a line with three
samples.
Table 4-13: GS2972 SD Audio Group 1 Audio Sample Distribution - 525 line
Samples
Lines
[3]⁽⁶⁾,[4],[3]⁽³⁾
31
10
[0],[3]⁽¹¹⁾
33
12
([4],[3]¹⁵)¹⁵
735
240
[4],[3]⁽¹⁰⁾
34
11
[0],[3]⁽⁴⁾
12
5
([4],[3]¹⁵)¹⁵
735
240
[4/3],[3]⁽⁶⁾
22/21
7
GS2972 3G/HD/SD-SDI Serializer with Complete
SMPTE Audio & Video Support
Final Data Sheet Rev. 9
GENDOC-047479 September 2013
www.semtech.com
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