108 Operation of The Camera
12.1.2 External recording
Uncompressed HD and unprocessed ARRIRAW data is available via the
REC OUT for recording with external devices.
The preferred output format also depends on the application. As a rule of
thumb, the following guideline can be used:
422 1.5G: Television applications that only require color correction,
high-speed capture above 30 fps
444 1.5G: High-quality television applications that require color
correction and pulling mattes, cinema applications
ARRIRAW: High-quality cinema applications for multi-format
distribution
422 1.5G YCbCr
422 is a color sub-sampled format, meaning that the camera-native RGB
image is transformed to YCbCr color space. Y represenst luminance, while
Cb and Cr are color difference signals. These are sampled with only half the
horizontal resolution, as the human eye is less sensitive to color resolution
than to luminance resolution. As a result, bandwidth is saved in transmission
while receiving good visual results.
For frame rates up to 30 fps, 422 1.5G is transmitted over 1 HD-SDI cable.
REC OUT "A" and "B" carry the identical signal independently. Frame rates
higher than 30 fps require 2 cables, and the image signal is carried by REC
OUT "A" and "B" combined.
422 3G YCbCr
3G is an improved HD-SDI format that can transmit signals over 1 cable
which previously required two cables. It transports the same signal as 422
1.5G YCbCr dual link, but over one cable with a higher clock rate. REC OUT
"A" and "B" carry the identical signal independently.
444 1.5G RGB
444 is still in the RGB color space, and each color has its full reolution. This
is important when pulling chroma keys, as these rely on color resolution.
444 1.5G is transmitted over 2 HD-SDI cables, where each of both links
carries a part of the image data. It is important to
connect REC OUT "A" of the camera with REC IN "A" and REC OUT
"B" of the camera with REC IN "B" of the recorder
use cables of equivalent lengths for link A and B
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