Cobalt Digital Inc 9061 Product Manual page 16

Up/down/cross converter with analog/sdi input, audio embed/de-embed, frame sync, timecode, and closed caption support
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1
3-2 Pulldown
(From 1080p 24 To 1080i 60)
2
"
" portions consist of two consecutive interlaced fields sourced from the same film
frame. The first film frame and first video frame are unique as a set in that their
contents are mutually and exclusively related to each other.
A
1080p 24
2
1
1080i 60
B
A
A
O
O
E
1080i 60
A
1080p 24
A
A
O
E
[1
1
]
O
E
Using reverse pulldown, each film video frame is constructed from 2 interlaced fields with odd and even fields selected
as shown. The conversion pattern shown reverses the pulldown, thereby restoring the original signal.
Note: If the original interlaced material does not have the cadence described here, the conversion reverts to standard
de-interlacing. While this video can be converted to film rates, the resulting image motion will lack smoothness.
Therefore, make certain interlaced video is appropriately constructed for reverse pulldown when converting video to film
rates. Similarly, formats using a 30/29.97 Hz progressive frame rate can be converted to a 24/23.98 Hz progressive
frame rate, however some image motion irregularity will appear in the converted output.
3-2 Reverse Pulldown
From 1080i 60 To 1080p 24
1-12
3-2 Pulldown Conversion and Considerations
Figure 1-3 depicts the 3-2 pulldown process used for conversions between
progressive film video formats and interlaced video formats. (Although the
term "3-2" is used here per convention, it is more accurately described as 2-3
per the diagram here and SMPTE definitions which stipulate that first film
frame
be represented exclusively by 2 fields from the same frame). As
A
shown in Figure 1-3, the term 2-3 is derived from the pattern, or cadence, in
which four consecutive film video frames are converted into five consecutive
interlaced video frames (i.e., 10 interlaced video fields). Odd and even inter-
laced fields are denoted in Figure 1-3 by "
"
"). Note the considerations described in Figure 1-3 for converting to film
A
E
rates.
3
"
" portions consist of three consecutive interlaced fields sourced from the
same film frame distributed across three consecutive interlaced fields.
B
C
3
3
2
3
2
4
B
B
C
C
D
E
O
E
O
E
X
X
B
C
B
B
C
C
O
E
O
E
[2
2
]
[4
3
]
O
E
O
E
Figure 1-3 3-2 Pulldown and Reverse Pulldown
A
D
2
1
5
A
A
D
D
O
E
O
E
A
D
D
D
A
A
O
E
O
E
[5
5
]
[1
1
O
E
O
E
9061 PRODUCT MANUAL
9061 Functional Description
" and "
" (for example, "
O
E
B
C
3
2
3
2
4
B
B
B
C
C
O
E
O
E
O
X
B
C
B
B
C
C
O
E
O
E
[2
2
]
[4
3
]
]
O
E
O
E
" and
A
O
D
3
5
D
D
D
E
O
E
X
D
D
D
O
E
[5
5
]
O
E
9061-OM (V4.9)

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