Extron Electronics VN-QUANTUM User Guide - Manual (Page 69)

VN-QUANTUM User Guide Section 3: Functional Overview
I455GB issue 8 Page 69
RAPT Image Bus
RAPT (Real-time Asymmetric Packetized Transfer) is a high-speed data bus used exclusively for the
transfer of digitized video and RGB source data between Input and Output Card(s). It is also used to
carry any VN-GLIMPSE sources to the Output Card(s).
Unlike PCI technology, RAPT is guaranteed to deliver data in real-time and to remain operational
even in the unlikely event of an operating system crash, allowing crucial source content to be
maintained on the target display.
Guaranteed Real-Time Performance
Real-time performance of the RAPT bus is defined as the ability to display a source at its full temporal
resolution (i.e. maintaining the same scan rate as the original source, without dropping any fields or
frames).
The RAPT bus can carry the equivalent of 48 full-resolution, full-motion video sources in real-time,
using 4:2:2 sampling and single-field de-interlacing, as summarized in the following table:
Maximum number of
Real-time Sources
Source Type Sampling De-interlacing
50Hz 60Hz
Single field – 48 NTSC 4:2:2*
Three field – 24
Single field 48 – PAL/SECAM 4:2:2*
Three field 24 –
Single field 8 6 HD 1080i 4:4:4
Three field 4 3
HD 1080p 4:4:4 n/a 4 3
HD 720p 4:4:4 n/a 9 7
UXGA 4:4:4 n/a 4 3
SXGA+ 4:4:4 n/a 5 4
SXGA 4:4:4 n/a 6 5
WXGA 4:4:4 n/a 8 7
XGA 4:4:4 n/a 10 8
SVGA 4:4:4 n/a 17 14
*4:2:2 is the default sampling rate for SD video. 4:4:4 is available as an
option but in most cases this will not offer significant improvement in image
quality and will reduce the maximum number of sources by around 33%.
The maximum number of sources can be greatly increased when displaying sources at less than their
native spatial resolution. For example, if sources are displayed at one quarter of their native spatial
resolution, four times as many sources can be accommodated on the RAPT bus while preserving full
temporal resolution:
Source Format
Resolution
De-interlacing
Max. No. of
Real-time Sources
Single field 48 Full Native Resolution
NTSC (720x480)
PAL/SECAM (720x576)
Three field 24
Single field 192 — Quarter Resolution –
NTSC (360x240)
PAL/SECAM (360x288)
Three field 96
– Scaled-down by Input Card.
— A maximum of 144 sources can be viewed simultaneously by using 12
input cards and 3 output cards.