EVS XT[2] User Manual

XT Series DISK RECORDER - Version 10.03 - Hardware
Technical Reference Manual
Issue
10.03.B
EVS Broadcast Equipment SA
–
July 2010
21
IMPORTANT RECOMMENDATIONS
• For 6-channel configuration, maximum bitrates for Avid DNxHD® or Apple
ProRes 422 should be 220Mbps (NTSC) or 185Mbps (PAL).
• “Super Motion + 1 Cam” configuration (i.e. 1 Super Motion REC + 1 Std REC + 1
Super Motion PLAY + 1 Std PLAY): maximum bitrates for Avid DNxHD® or Apple
ProRes 422 should be 145Mbps (NTSC) or 185Mbps (PAL).
• When using the Avid DNxHD® codec, we advise to work at 100Mbps if the
picture quality is satisfactory Æ the XT[2] can sustain 6 local channels + 5
network transfers.
1.9.8 RAID LEVEL: 3
The Video Raid uses striping process across 5 disk drives. The video and audio
data is striped over the first 4 drives while the parity information is saved on the
fifth drive. If one drive is damaged, the Video Raid can use the parity information
to recover the missing information, so that operation can continue seamlessly
without bandwidth loss.
For more information on online rebuild, refer to the section dedicated to this
subject in the XT Technical Reference manual.
1.9.9 INTERPOLATION
The playing back of smooth slow motion pictures carries specific issues: since
some fields must be repeated at regular interval to provide the video at the
playback speed required by the operator, parity violation appears regularly on the
output video signal. This issue is specific to interlaced formats (525i, 625i and
1080i) and does not concern progressive formats (720p and 1080p).
If O and E represent respectively the odd and even fields of a standard video
signal (50/60 Hz), we have:
The original video signal:
O E O E O E O E O E O E O E O E
The output video signal at 50% speed:
O O
E E O O E E O O E E O O E E
The output video signal at 33% speed:
O O O E E E O O O E E E O O O E
The output video signal at 25% speed :
O O
O O E E E E O O O O E E E E
Fields with parity violation are shown in bold, underlined letters. As it appears
from the above table, whatever the playback speed (with the exception of the
normal 100% playback speed), a number of fields violate the normal parity of the
output signal. This parity violation induces a 1-line shift of the field, resulting in a
vertical jitter of the picture. The jitter frequency depends upon the chosen
playback speed.
To avoid this phenomenon and provide a stable output picture, EVS developed 2
types of line interpolator: 2-line and 4-line interpolators. The interpolation process

EVS XT[2] Specifications

General

Brand	EVS
Model	XT[2]
Category	Server
Language	English