GRASS VALLEY PROFILE XP PVS Series, System Manual

Page: 158 / 352

Chapter 5 Modifying a Channel: Video Settings
158
Profile XP System Guide 23 July 2004
Selecting video quality for a channel
NOTE: Quality selections are not applicable to DVCPRO channels.
You can manage storage capacity and video quality by adjusting the channel MPEG-2
compression settings. If you have enabled browse video for the channel, you can adjust
the MPEG-1 settings in a similar manner. Using the Video Quality and Browse Video
Quality drop-down lists, you can change compression settings by selecting one of the
video quality presets provided (shown in the table), or you can define and select a custom
preset. Selecting a preset determines the data rate, chrominance sampling method and
group of pictures (GoP) structure used during recording.
You can select MPEG D10 bitrates of 30, 40, or 50 Mb/s from the Video Quality
drop-down list.
Guidelines for selecting Video Quality Presets
With the Profile XP Media Platform, you can improve picture quality for your available
storage capacity by selecting chrominance sampling method and GoP length for a given
video data rate.
The type of video and how it will be used largely determines the compression settings
you should select. It is important to understand the type of material you will be
broadcasting and select the appropriate compression settings.
Use the following guidelines when choosing one of the video quality presets or defining
and selecting a custom preset. For more information on the relationship between picture
quality and the type of video, data rate, chrominance sampling method, and GoP look for
Quality Preset MPEG-1 Data
rate in Mbps
(Browse Video) MPEG-2 Data
rate in Mbps
(Standard Def) MPEG-2 Data
rate in Mbps
(High Def) Chrominance
Sampling
Method
Group of Pictures (GoP)
*
*
Profile XP applications can play but not record clips using open GoP. However, third party applications can be written for the
Profile XP system that do both.
Draft .4 4
4:2:0
†
†
Video recorded at 4:2:0 on the Video Processor board (PVS1100, PVS3000, and PVS3500) begins at line 23, and so does not
include VBI information such as VITC in the compressed video.
IBBPBBPBBPBBPBBP
(PVS1000)
IBPBPBPBPBPB (PVS1100,
PVS3000, PVS3500)
Low .8 8 30
Medium (default) 1.2 15 50 4:2:2 (4:2:0
only in HD
and browse
video)
High (VHS
Quality, default
for browse video) 1.5 24 80
Custom 1 to 4 .3-1.5 in
increments of .1 4-50 in
increments of 4
(12 default) 4:2:2 (default)
or 4:2:0
(default for
browse video) Choose from I, IP, IBP, IBBP,
IBPBP, IBBPBBP,
IBPBPBPBP, IBBPBBPBBP,
IBBPBBPBBPBBP, and
IBBPBBPBBPBBPBBP
(PVS1000) or,
I, IP, IBPB, IBPBPB,
IBPBPBPB, IBPBPBPBPB,
and IBPBPBPBPBPB
(PVS1100, PVS3000,
PVS3500)