Sound Devices PIX 270i - Manual (Page 37)

PIX 270i User Guide and Technical Information
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V
ideo Scaling and F
rame R
at
e Con
ver
sion
Video Scaling and Frame Rate Conversion
The PIX 270i features powerful, hardware-based video scaling, frame rate conversion, and de-inter-
lacing. This allows for converting the resolution and frame rate of input video signal to the recorded
file and to the HDMI and SDI outputs in real-time.
Video scaling and/or de-interlacing is active whenever the Setup Menu option
[Video - File Resolution/Rate] is set to something other than Same as Video Input. Any sup-
ported input signal can be converted to any available resolution. When set to record progres-
sive frames, the PIX 270i will convert incoming interlaced video to progressive frame video
via its built-in, powerful, hardware-based de-interlacer. The PIX 270i will also convert progres-
sive segmented frame (PsF) video to progressive video automatically if Setup Menu option
[Video - File Resolution/Rate] is set to a progressive frame format (for example 1080p30). If Setup
Menu option [Video - File Resolution/Rate] is set to interlaced format (for example 1080PsF30), the
PIX 270i will record PsF signal unaltered, but the file will be stamped as interlaced.
Frame rate conversion occurs whenever the frame rate of [Video - File Resolution/Rate] differs
from the frame rate of the input video signal. Frame rate conversion is achieved by appropriately
duplicating or dropping frames. The PIX 270i will auto-sense between integer and non-integer frame
rates (for instance 30 frames vs. 29.97 frames). The PIX 270i will not frame rate convert between
integer and non-integer frame rate values. For example, if the incoming video signal is 1080i59.94,
it can be converted to 1080p29.97 or 720p59.94 but not 1080p30 or 720p60. The Setup Menu option
[Video - File Resolution/Rate] contains entries with a combination of integer and non-integer frame
rates (such as 1080p30/29.97). When any of these options are selected, the PIX 270i will record in the
indicated integer frame rate if the input video is an integer frame rate or record in the indicated non-
integer frame rate if the input video is a non-integer frame rate.
Not all frame rate conversions are visually desirable. When the OSD Item File Resolution/Rate is
red, the conversion of the frame rate of the input video will contain a finite amount of motion judder.
For example, if the incoming video is 720p60 and [Video - File Resolution/Rate] is set to 720p50,
the cadence of dropped frames may be noticeable depending on the content. Conversions that are
simply 1:2 or 2:1 (such as 1080i59.94 to 1080p29.97) introduce no motion judder. For these conver-
sions, the OSD Item File Resolution/Rate remains white.
When the input video signal is 720p24 or 720p23.976, up-, down-, and cross-conversion is not available.
3:2 Pulldown Removal
Many cameras which shoot with a shutter speed of 24/23.976 frames per second will output signal
on the HDMI or SDI output at 60i/59.94i. To achieve this, the camera performs a “3:2 pulldown”
process. The 3:2 pulldown process splits each frame into 2 fields and duplicates a field periodically.
The PIX 270i is capable of removing 3:2 pulldown from a 60i/59.94i signal and converting it back to
24/23.976 progressive frames per second in real-time. The PIX 3:2 removal process actively views
video fields looking for duplicates. When these duplicates are sensed, then this cadence is locked in
and the appropriate extra fields are removed. The process depends on motion in the incoming video.
The OSD item File Resolution/Rate changes from orange to white when this cadence is detected: