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Factors that affect picture quality when Recording
QuVIS video servers, including the QuVIS Acuity, have several settings that affect picture quality in different ways.
These can be categorized into two broad groups:
those that affect picture quality directly (such as the SNR
control) and those that limit the picture quality possible (controls related to data rate management, which may in
turn limit picture quality).
Following are the items that affect recorded picture quality.
External Factors
Source Material
Image quality cannot be improved beyond that of the source material. The motion content, clarity and grain of the
source material will have some affect on the data rate of the recorded footage.
Signal Chain
Image processing components (noise/grain reducers, VDAs, etc) in the signal chain itself can degrade picture
quality.
Internal Factors
1.
Image Quality (Record Video menu page)
This control has the greatest direct affect on picture quality.
Note: Using a high SNR with a low MDR can force a situation where the failsafe is turning on too often. It’s
best to match the SNR setting to the source material, or set it only slightly above the SNR of the source
material, to avoid the data rate reaching the MDR setting.
2.
Maximum Data Rate (Record Video menu page)
MDR can have a moderate to more extreme effect on picture quality, based on whether it is set correctly or
incorrectly for the source material and SNR. Set correctly, it will monitor and gently soften image quality only as
needed for extreme peaks in the data rate. If set incorrectly this setting can cause the system to constantly turn
on the data rate failsafe which can artificially lower image quality.
Note: The data rate failsafe mechanism lowers image quality when the data rate exceeds the MDR setting.
Using a high SNR and a low MDR can force a situation where the failsafe is turning on too often. It’s best to
match the SNR setting to the source material, or set it only slightly above the SNR of the source material.
3.
QuVIS Media Format (Record Video menu page)
QMF selects between legacy-format clips and new clip formats with three data rate cap options: MDR30,
MDR60 and 250Mbit/sec (JPEG2000 formats only).
4.
Destination volume capacity (Record Video menu page)
The destination volume may contain one to four hard disk drives. A one-disk volume cannot receive data as
fast as a volume with two or more drives. Recording 60p or dual-link HD-SDI content to a single-drive volume is
not recommended as the system may find it necessary to soften the picture quality if the peak data rate
exceeds the performance capabilities of the single hard drive.
QuVIS Acuity
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